Green Building Forum - All Discussions

New Green Building Forum & Website

BWork — Mon, 01 Sep 2025 15:58:30 +0100

Crowd funding

Greenbuilding.co.uk, owned by the AECB, promotes excellence in design and construction. This website, including the very popular Green Building Forum, was set up by Keith Hall, who co-founded the AECB back in 1989. Keith kindly donated the site to the AECB on his retirement in 2025.

The Greenbuilding site is for everyone from industry professionals including architects, builders, developers to green enthusiasts and homeowners looking for information and a place to discuss all aspects of sustainable building.

With the money that we hope to raise from this Crowdfunder we will be able to update the original website and forum, currently working using older technology that does not allow for necessary changes to the platform. With your support of a much-needed funding boost we will be able to invest in new technology that will bring the site into the 2020s. This will make it easier for visitors to navigate around the site and read the valuable information and resources we share, for those on their sustainable building journey. Users will also be able to sign up quicker and get involved in the conversations.

https://www.crowdfunder.co.uk/p/qr/dyR52gZn?utm_campaign=sharemodal&utm_medium=referral&utm_source=shortlink

Welcome to Guests

GBP-Keith — Tue, 15 May 2007 18:00:44 +0100

Subscribing to and participating on this forum is no longer available to new users from December 2023. However it is a great resource to browse. Existing subscribers can continue to participate as normal.

PH barn?

fostertom — Mon, 07 Sep 2026 18:55:40 +0100

Part Q barn conversion, steel frame portal, 115m2 2-bed, almost cubic, severe restraint on vertical/headroom, every milimetre counts.

Hence only 25 PIR over the extg reinf conc slab with 32 timber floating flooring, but downstanding 'coffer dam' of 250 EPS (continuous with wall insul) in slit trench 1200 deep, french drain at bottom, gives floor 0.25U, the BldgRegs Table 4.2 'improved' figure, as the whole is a Material Change of Use, not newbuild. The block of subsoil beneath, inside its 'coffer dam', will somewhat adopt an intermediate temp which will be partly-ground-coupled to the interior via the weak insulation.

Blockwork ground floor and stairwell partitions built off the slab on insulating strip stuff (so penetrating the weak floor insul hardly matters) add more interior massiveness. As ever-strengthening heatwaves become the norm, overheating at least as important as winter loss, internal massiveness has new importance.

Roof and walls can have extremely good insulation, airtightness and continuity, copiously through-ventilated (vertical bris-soleil?) to keep cladding cooler, as well as shielding from winter clear-sky cold. Windows thoroughly shaded by brise soleil etc.

Question is - is PH, no heating system, within reach? Though not the classic PH approach, would PHPP be impressed by insulation elsewhere compensating for the floor, internal massiveness and ground coupling particularly as affecting overheating, walls and roof shading?

If not, it's a centralised plan, so AAHP with very short ducts, incl AC (why not, as well as the passive overheating measures?) which might do the DHW, and/otherwise night-store, and wet solar - is that still a thing? MVHR of course.

How to make a complicated penetration airtight?

djh — Sat, 05 Sep 2026 12:18:31 +0100

I'm looking for advice and reassurance! We're planning to fit an air-air heat pump to replace the direct electric duct heater we presently use to heat our house, and to provide cooling in summer. It's a conventional split unit with internal units and an external condenser unit. To connect the internal and external units we will need to make 60mm holes for the refrigerant, condensation and power in a conduit.

I'm planning to make the holes in areas where there is warmcel insulation instead of straw bales, so as I remember the construction from inside to outside is:
- lime plaster (30mm or so)
- 15mm Savolit board
- Intello Plus membrane (connected to lime plaster over straw bales with mesh
product)
- muslin to contain Warmcel
- 450mm of blown-in Warmcel
- 25mm Savolit board
- lime render (40mm or so)

My thoughts are to drill from the inside, starting with a pilot hole. Are there likely to be any issues to watch out for?

My other worry is airtightness. The main airtightness barier is the internal lime plaster but there are places (such as these areas) where the airtightness barrier is the Intello PLus membrane and it is connected to the plaster with Pro Clima Contega PV tape. We used Dafa pipe and cable collars or Siga Rissan tape to seal penetrations. Lots of short lengths of Rissan around the MVHR ducts and around the incoming water pipe for example.

I'm not sure how best to seal a 60mm pipe containing several other pipes and a cable though, and in theory it should be sealed to the Intello Plus although sealing to the plaster seems a lot easier. Any thoughts on the best approach?

https://proclima.com/products/connections/window-sealing/contega-pv
https://www.siga.swiss/gb_en/products/rissan

Clay roof tiles with a Nordic feel

Victorianeco — Tue, 08 Sep 2026 23:16:48 +0100

Can anyone recommend brands that fit the bill?

We don't want concrete as they fade over time, we have realised we won't get away with a re-roof in our area with standing seam or corrugated due to planning and keeping the street similar.

So we need to pick slates or tiles but we're thinking larger format tiles will achieve the look we are aiming for.

Any pointers on this?

CAT6 male plug

Rex — Tue, 08 Sep 2026 11:30:01 +0100

What ho one and all,

Having managed to fish the CAT6 cable fro the loft (second floor?) to the g/f office space, I need a 3m length to connect form the wall socket to the router (when Openreach finally manage to install the fibre; at the moment, this year, next year sometime, never!!)

The cable is a factory made, 50m with male at each end. I wonder about cutting a 3m length off, and fitting a male plug to each cut end, then I will have the necessary extension. But.... how do I know which wiring standard the factory fitted plugs? Either T568A or T568B? Is there a way to determine? Or is it just a case of wire one way and if it does not work, try the other?

Although I hardly need an RJ45 network tester, by chance, my favorite Lidl has them on sale today so bought one for the mega sum of £4.99.

roofing slates

rsk1 — Sun, 08 Jan 2017 19:32:57 +0000

Can anyone give a comparison of the eco credentials of real versus artificial roofing slates? And while we're at it, any other kind of comparison such as longevity and cost

Passive house V rodents

Beau — Sun, 18 Nov 2012 07:52:17 +0000

At the moment I am fighting a battle with rodents chewing there way into our house. Now our place is not super insulated or airtight so the effects this damage being caused it not going to have a massive effect but I was thinking if you are working on PH what extra precautions should be taken to prevent rodent damage to the air tight layers?

Solar Options

Victorianeco — Sat, 05 Sep 2026 20:55:02 +0100

Up to date solar recommendations?

Any grants available?
Preferred kit setup and size?
Export tariffs available?

I have little knowledge on the subject and we're a few weeks away from scaffold going up for the re-roof currently looking at cladco corrugated profiles and greencoat roofing systems but may be swayed by standard slate or tiles, but 100% confirmed either way.

But would like to start getting a few solar quotes together but looking at specs. to ensure I'll be comparing apples with apples in the quotes.

We have a cross gable roof with one elevation facing true south and the other roof section is half east and half west.

Let me know your thoughts on what the ideal setup is these days

Wall Build-up for timber frame structure validation

Oj0001 — Tue, 25 Aug 2026 14:38:05 +0100

Hey,

I’m currently in the progress of building a single story extension on the rear of my house, located in the midlands.

For the extension I drew up and got approved plans for a timber frame structure. The wall build up from inside to outside is currently:

15mm plasterboard
145mm studs with 100 PIR. (Resulting service space to inside, all joints tapped for Vapor sealing)
11mm OSB
Vapour barrier
70mm EPS with direct render.

However, since then I have read more into interstitial condensation, and under winter conditions there is a risk at the outside face of the PIR could suffer, this is behind the OSB and could lead to issues. Also the OSB becomes sandwiched between two layers, although EPS should have some permeability.

So far I’ve looked at :

-Increasing the PIR to 140mm and adding an internal service void does not seem to resolve it.

-Switch to 140mm Rockwool between studs. (Decreased performance notably, but increase breathability). Still need to add internal service void as internal vapour layer needed.

-Switch to internal PIR layer, add external ventilated cavity and render board. Also considered external PIR to reduce thickness, then cavity and render board.

Really just looking for a sanity check, is there a fundamental issue with the project as designed, is there a way to add improvements, or does anyone have experience with similar?

There’s a lot of discussion on similar build ups on here, but nothing quite the same.
Any and all help is appreciated!

Window Detailing CWI v CWI with EWI

Victorianeco — Sun, 30 Aug 2026 09:27:39 +0100

1960's uninsulated property

Still undecided if I'm going to adopt the fabric first approach (focussing on CWI beads and then EWI with windows in the insulation layer)

or

More later research focussing on reducing embodied energy at source and just use CWI beads and then silicone render over existing.

Just wondering if anyone could share the optimal window fitting detail for each approach and how I could mitigate thermal bridging particularly if I adopt the latter approach?

Property is currently ~20mm render on external reveals and PB and skim internally on the reveals but solid render/skim on the internal walls.

Windows will likely be alu-clad 3G from Allan Brothers, property will be having ASHP and solar.

I know I've harped on about which approach to take but this decision of CWI v CWI with EWI is holding up the project and causing conflict with her indoors.

Property in question linked below for context:
https://drive.google.com/file/d/12ZZsoLmjjSMoA4AW8HBQ_oQzmi9waWuE/view?usp=drivesdk

Sub floor ventilation

Artiglio — Thu, 03 Sep 2026 13:33:20 +0100

Good day all.

Over last 5 years , i’ve been renovating and improving a listed property, (old barn with attached cottage), in the cottage section, there are 3 parts , original cottage and a 1930’s extension, added coal store (now included in cottage) again 1o30’s.
This has a mix of solid and suspended floors. Lots of alterations over its history. When floors were lifted, lots of rubbish and debris beneath, all cleared out. Evidence of previous damp / rot. But once cleared this all dried out over a year or so. There were only air bricks in the main extension, 6 more were added and ducted under solid floors where needed. A mix of insulation methods as it was all reinstated. All’s well and good most of year. But in hot humid periods ( i’m half mile from coast) i get a musty smell, that’s seemingly coming from under the floor.

My thoughts are it’s moist air condensing under the floor sufficiently to allow a bit of mould/damp. The void space is mostly about a metre deep, cool and has a lean mix blinding ( this was there already). Whilst i’d tried to make sure that there was good airflow patently it’s not been enough.

I’m considering adding some forced ventilation using a constantly running fan to draw air out via an airbrick that’s ducted to what i believe is the problem area. The air being drawn in via the other airbricks.

Is this a sensible way forward or am I risking just drawing more moisture into the area and adding to the problem? Is constant low volume flow any better or worse that going for periodic high flow (downside of background noise) either way the fans will be on a voltage controller so that extraction rate can be varied.

I expect there’ll ne the suggestion of adding a humidity sensor to the problem area to control the fan. That is’nt going to be practical now that this section of the house is now finished. I’d rather add the fan and see if it makes a difference then consider if the amount of work to add a sensor is worth any likely improvement ( especially if a low volume fan works).
Fan i’m considering has a max air flow of 180 m3 /hr.
Lastly whilst my intention is to extract, would it be better to force air into the suspected area instead?

Many thanks.

Water saving: grey water top-up

Doubting_Thomas — Fri, 28 Aug 2026 17:11:51 +0100

Hello again.

Since it's on everyone's minds right now, we've been discussing how we can use less water at home. One idea is using cold bath water to top up our WC cistern.

Ours is a concealed cistern (Geberit Duofix) so the proper access is via a removable faceplate. The idea with this would be to introduce a separate hole and hose arrangement on one side, with some sort of inlet valve to allow topping up the water level using a watering can or jug filled from the bath.

Any suggestions for what we could use at the filling end? All I can think of is some sort of wall-mounted tundish like the below.

Also, is this mad? Anything we should be wary of, other than probably needing to de-scale/clean the cistern more frequently?

IBC rainwater storage

Rex — Fri, 07 Aug 2026 15:32:33 +0100

What ho one and all,

Have a 6000 liter rainwater collection tank in the garden (mainly for toilet flushing but also garden use) and it has of course, been empty for the past two months.

Wish I had installed an even larger tank but 15 years ago, who could predict this extended drought.

So at the behest of SWMBO, I am investigating most likely, one (or perhaps two) IBC and how to fill. Obviously, the best location is somewhere that I can divert rainwater but the design of the house is such that the only place would be against a side wall and these are somewhat ugly things.

Since the loft tank (for flushing) is filled by a submersible timer pump, I could access the pipe and T off to an IBC situated in a less obnoxious location. But is it possible to install a ball valve in an IBC so that when fill, it does not overflow?

I have not researched this idea but thoughts would be welcome.

CAT6 install

Rex — Wed, 26 Aug 2026 13:32:37 +0100

What ho one and all,
Thought I had a separate CAT6 thread but only topics relating to my attempts, namely toilet seat and plasterboard.

Knowing that y'all are sitting on the edge of your seats, after a lot of procrastination and alternative plans, plus attempting limited demolition (Right said Fred, gotta take the wall down!), persistence has paid off and yesterday, I found the fish rod end and have finally have the CAT6 cable form the loft (second floor), horizontally through the Posi-joist / Warmcell floor/ceiling and into the wardrobe. From there , it will be a simple vertical drop to where I will install the CAT6 socket.

Don't recall any job where I have been so persistent in my efforts.

I won't make good until the fibre to the house is installed and I know the CAT6 is working; then a simple decoration job.

I did not remove the toilet but did remove the small cabinet beside the toilet which allowed me to bore another 100mm hole into the 22mm OSB to get a better angle.

Appreciate all the advice and suggestions.

Broadband and VoIP

Rex — Sat, 04 Jul 2026 14:48:15 +0100

What ho one and all,

Frequently happening as I get older, I am getting my knickers in a twist as technology leaves me behind.
At the moment, broadband and landline is with PlusNet via fibre to the pole. We are not paying for the landline, but it does receive incoming and we would pay per minute for outgoing calls.

My contract is ending but PlusNet are no longer offer a landline, just Full Fibre b/b. However, their associate company EE, will offer full fibre to the house and I assume, VoIP to keep the phone and phone number.

I am told that an engineer will have to assess how to get the fibre to, and then, into the house. At the moment, it is overhead to the front roof apex, then phone cable to the various RJ45 sockets which was part of the building process. The ''customer help' was not exactly helpful with my questions, but ......

Fibre has to come to the router which if it was in the loft, can I then use the existing wiring to the computers on the g/f?

The 'unhelpful' assistant was suggesting the fibre will have to be routed down the wall then drilled through the wall to where the office is located. The house is timber frame with Warmcel insulation. There is the breather paper on the frame (but that is inside the cavity) and internally, there is scrim under the Fermacel. Drilling through either of these materials is like drilling into a ball of wool; it just rips everything to shreds.

How does a fibre cable come into a very well sealed house if it has to be drilled through the frame and insulation? Once inside the house, can I use the existing wiring to use additional computers in different rooms?

Thanks and toodle pip

Garden Slab - Future Planning

Doubting_Thomas — Tue, 25 Aug 2026 16:01:56 +0100

I have an area behind the house, 2.5m x 6.5m, where I plan to put various outdoor storage: bike shed, composter, raised beds, possibly IBC rainwater tank (inspired by another thread). Eventually it could even become the floor of an outdoor 'garden room' of some kind.

It feels sensible to pour a level hard standing here as a base for all of the above. My current thought is a concrete raft slab of 100-150mm thickness would be more than enough support, but I'm open to suggestions on this.

Three sides are enclosed by ~2m high concrete retaining walls supporting neighbour's gardens, so formwork along the remaining edge should be straightforward.

My questions are:

- Should I insulate and/or damp proof below it, anticipating the potential ultimate use as an outdoor room? Or are these generally raised up on pedestals anyway?

- Will I need reinforcement and or movement/expansion joints in this footprint?

- Anything missing? Ducting for electrics perhaps?

I realise this could spiral into a full-on house slab if I'm not careful, and I'm keen to keep things simple and affordable. More likely than not it will remain a concrete extension of the patio for many years - I just don't want to miss an opportunity for some future-proofing.

NB - I can't dig down much deeper for the risk of upsetting the retaining walls, so underground nuclear bunkers aren't going to happen!

Making good a cracked footpath

thebeacon — Thu, 20 Aug 2026 11:33:40 +0100

Hello,

I’m seeking some advice on making good the pathway at the front of my house. Its currently a 50-100mm slab of concrete which has some cracks and a drain in. The water currently runs towards and pools in front of the door.

I would like to repair the footpath and add a slight ramping in front of the door to direct the water to run away from the house. The entire path is about 2.6 x 1.3m. I imagine some areas would need 40mm while others less than 10mm.

I’d rather not break out the entire slab and add a resin based concrete product on top. Does anyone have any experience or advice with doing this? I have been looking at Cretex® EP Mortar (https://polycote.com/contact/) as a possible option to use.

Thanks,
Tom

Embodied carbon, EWI, CWI, ASHP, Exposure zone 4

fostertom — Thu, 11 Jun 2026 11:42:34 +0100

A multi-faceted issue:

1. The new thinking, which removes high-standard External Wall Insulation (EWI) from its pedestal as the default/ideal for retrofit, on grounds that the embodied carbon (i.e. the CO2 and CO2-equivalent released to atmosphere) created in 'quarrying', manufacturing, transporting and installing EWI, is likely to exceed, sooner and for longer duration, the in-use carbon it saves over the building's subsequent lifetime.
Couple that with the rapidly declining carbon content of mains electricity, which means that electricity consumed over the building's in-use lifetime, already and increasingly carries little penalty in global heating.
Then, compared to super-insulation hence consuming minimal energy-in-use, the alternative of omitting the super-insulation hence consuming plenty of 'harmless' electric (via heat pump) energy-in-use, can actually be a lot better for planetary climate, both in this emergency-short-term, and over the building's lifetime.

2. Retrofitting the 30% of UK building stock which is still-uninsulated cavity wall, with or without EWI the cavities should be filled (CWI), as it's near-impossible to prevent outside air blowing around in the cavity. Even fitting EWI can't be relied on to seal the multiple cracks, entry points and open-to-loft top of typical cavities - outside air is still liable to bypass the EWI, separated from the interior only by the inner skin. External render can't be relied on either. Even Partial-fill CWI is poor at preventing outside air blowing around in the cavity; it really needs to be full-fill CWI.

3. CWI is cheap to install, with small embodied carbon. So, considering both 1. and 2. above, the new default looks like installing full-fill CWI, without EWI, along with electric (via heat pump) energy-in-use. In which the CWI is an indispensable part, hardly works without.

4. But what about cavity-wall buildings in high-exposure areas? There, CWI is pretty much banned by Building Regs, certainly with traditional 50 wide cavities (as opposed to more recent 100-ish cavities) and certainly in exposure Zone 4 areas (i.e. most of the west/southwest of UK). External render doesn't help.
https://assets.publishing.service.gov.uk/media/606c366ad3bf7f400e10af54/wic-final-report.pdf also gives little hope that a coat of gunk would make the wall more suitable for CWI.
Does anyone know different?

5. Without CWI, a house has nearly zero insulation, if outside air is blowing about only separated from the interior by the inner skin - even if accepting plenty of 'harmless' electric (via heat pump) use. Especially if extending an unfilled cavity-wall house; the existing cavity wall becomes an internal wall, but super-cooled because its cavity is continuous with the still-external parts of the cavity wall adjacent.

6. Similar applies if you've EWI'd your half of a semi-detached house; your unfilled cavity, inside the EWI, will be super-cooled because continuous with next-door's unfilled cavity.

So WTF to do about all this? Any solutions, bright ideas?

MVHR, heatwaves, chiller?

john.connett — Thu, 02 Jul 2026 12:54:37 +0100

My house in Cambridge had a low energy renovation around 15 years ago with triple glazing, increased thermal insulation, solar thermal system, thermal store and MVHR. The MVHR unit is a Vent-Axia Sentinel Kinentic BH.

For most of the time since it was installed it has worked very well and I rarely needed to open any of the windows. However, during the recent Amber Heat Alert the house overheated badly. Possibly the high humidity made it worse than in earlier years or my age and, maybe medication, made me less resilient.

My suspicion is that during an extended heatwave with tropical nights the MVHR is unable to maintain comfortable indoor temperatures. With or without a summer bypass, if the air temperature is over 35º C outside then the MVHR will import that air. Even if the air temperature drops lower overnight it can't catch up and the house continues to retain the heat, made worse by the high quality of thermal insulation.

Some form of air cooling may be required! My back garden is nowhere near big enough for a ground-coupled heat exchanger so active cooling may be an option.

I have seen an example where a reversible heat pump was connected to a water/air duct heat exchanger (eg. Zehnder ComfoPost). However, my house has a gas boiler.

Has anyone else experienced similar problems or can suggest possible solutions?

Water prices

Rex — Sun, 16 Aug 2026 17:16:07 +0100

What ho one and all,

The headline on the front of today's Telegraph is what can only be described as 'surge pricing' for water during droughts. The aim is to encourage us to use less water.

This really anger me as we have a 6k liter rainwater collection tank and apart fro the fact that I'm not paying for incoming and by default, sewerage charges for using that water, I am unlikely to get any consideration for the fact that I am using less treated water than most houses.

With all the building regs we have in place, surely it makes sense that every new build, whether single houses or estates, must have a large rainwater collection to be used for toilet flushing. After all, every new build has to have a large soak-away, so why not collect that water before it goes to the soak-away?

It is absolute madness to flush expensively treated, potable water down the lavatory.

Now I'm off my soapbox!!

Solar Panel Fire

Rex — Thu, 28 May 2026 20:27:00 +0100

What ho one and all,

Just seen this on the Mail on Line web site.

https://www.dailymail.com/news/article-15854881/solar-panels-explode-home-explodes-flames-family-inside-escape.html

Will we ever hear why this happened? Bet the estate developers will have a nightmare with all the other owners wanting reassurance their solar panels will not catch fire. There is a 100 Taylor Wimpey built estate near me and they all have solar panels.

diseased or rotten oak in external application

northumbrian — Tue, 16 Sep 2014 20:27:21 +0100

Six years ago we installed some oak sleepers in soldier format for a client. We import the oak 400 sleepers at a time and use it for many varied external applications. We concreted the sleepers into the ground and told the client there was no great need for a treatment and that they would weather naturally and last a long time.
The client decided to treat the sleepers in a black treatment(variety not known at this time), and now is complaining that some have rotted.
ALL the other applications we used the same sleepers for are absolutely fine.

Can anyone shed any light on why this rot may have occurred in a relatively short period. Could it be something in the soil which surrounds their feet?
Could it be moisture that has been trapped in by a non breathable treatment?
Any suggestions would be welcomed as we have used green oak for years without a problem

Thanks in advance

Acoustic insulation between floors in old house

reed — Mon, 03 Aug 2026 18:19:19 +0100

I am looking for advice for acoustically insulating a 280mm void between ground floor and first floor. I have installed internal timber stud walls with mineral wool slab insulation on the external walls of my late Victorian house, I have insulated the suspended floor downstairs and I will insulate the loft space in the bedroom above. I have lifted the floorboards with a view to sanding them and relaying them in both bedroom and lounge with no carpet above. The old ceilings are down and I have not yet installed new ceilings. I need to reduce the drum effect which will exist if I do not install some sort of acoustic insulation between the floors. I would prefer not filling the whole enormous 280mm void with insulation for cost reasons and also I am not averse to leaking some heat from the lounge (woodburner heated) to the bedroom above. Am looking at various solutions but would happily receive comments on:
1. layer of insulation slab (Knauf RS45) next to plasterboard ceiling of lounge. Void above to the floor boards of the bedroom. What thickness slab? will the void above slab be a significant acoustic issue?
2. thicker layer of rolls of acoustic or loft insulation. Should be cheaper but I presume less effective? What thickness?
3. combination of solutions 1 and 2 but it seems a bit labour intensive and costly.
4. Decouple the ceiling by laying battens on the lower side of the joists before fixing plasterboard. How much impact does decoupling have? Not my preferred option due to limited height between the ceiling and the top of my windows

Many thanks

Toilet Seals

Rex — Tue, 21 Jul 2026 19:02:37 +0100

What ho one and all,

In my continuing quest to find a way to thread a CAT6 cable from the loft to the office, it may (only may?) be useful to remove the toilet to allow better access to the small area of floor below the pipe.

Not a big job, just a couple of screws and wiggle it free from the fittings. Of course, I would have ensured the cistern is empty.

But the toilet has been in place for around 15 years and I am wondering if the various seals should be replaced when re-installing, or are they all OK to reuse? Of particular concern would be the two yellow seals, which I assume are not replaceable. I would give a smear of silicone grease around the seal before reinstalling.

Your thoughts most gratefully taken on board.

Thanks

Replacing wind turbines

tony — Wed, 29 Jul 2026 16:49:47 +0100

I recently read about a scheme to replace wind farm turbines with new ones. Their idea was to remove the existing ones and put new ones up, much bigger ones. It might seem like a good idea because because all the cabling infrastructure will already be there but of course it won’t be suitable because the the output of the new wind turbines will probably be something like 10 times as much as as existing ones so the cables would need to be upgraded anyway.

My intention is that it’s crazy to take down in turbines that still useful. Why not? Just put the new ones up somewhere else then we’d have both the old ones and the new ones all functioning?

Shower

Rex — Wed, 29 Jul 2026 13:53:50 +0100

What ho one and all,

Me again!!!

I frequently feel that design somehow does not improve the function, and this is exactly the case.

As in the two photos below, I have one of these bath tap shower fittings. In the lower photo, push the right thing and it switches from bath filling to shower. But!!!!

Frequently, either this does not happen or if it does, the design malfunctions and upon turning the water off, it will not revert to bath or most frequently, supplies both shower and bath at the same time.

The left spring sits in a recess in the body of the tap, so should all be locked in place. Disassembly usually shows one of two things: 1/ The spring has somehow, become dislodged or 2/ one of the O rings has been forced by water pressure from its seat. The water is running at 3 bar because that is the recommended pressure for the softener.

How to resolve the all to frequent dismantling beats me. It happens pretty much every couple of months. I have investigated replacing the tap unit, but want the same, which of course is either no longer available or is surplus stock for around a very profitable £250.

Having dismantled, reset whatever is unset, reassembled, it will work as it should for a few months, then the cycle repeats itself.

Grateful for any insight into how to ensure the push button works every time as it should.

Thanks and toodle pip

Old window

tony — Thu, 30 Jul 2026 16:47:39 +0100

Just saw a window over 350 years old - yea it was a wooden window frame set into a stone surround.

https://share.icloud.com/photos/053drZp42Ur_dTRWMN-hRQb8w

Hope the link works

Aerogel insulation

Sandfordbarn — Mon, 26 Sep 2022 08:21:13 +0100

Hi, I'm refurbishing a stone barn, and am looking at aerogel.

Does anyone have any experience applying it directly to stone walls, in particular the blanket rather than the boards. Then direct plaster/lime over that?

I'm keen on this finish as I'd prefer a more irregular finish, rather than flat boards.

I've seen some European company are applying aerogel render externally (with aerogel granules in the render mix), but I've not heard back from any of them.

Any shared experiences on this would be very helpful - it seems to be a revolutionary product?

Hole in plasterboard

Rex — Mon, 27 Jul 2026 07:25:39 +0100

What ho one and all,

Continuing with a different topic but still related to my CAT6 cable saga, I think I am planning to cut at least one hole, and maybe two 10 cms holes into the plasterboard ceiling.

My wife wiggled the fish rod (oven sized earth wire) and I can clearly hear that it is kinda where I want it, but nevertheless, still around 10 cms+ away from where I can grab hold. The option is to drill an access hole ito the plasterboard ceiling, behind which is the Warmcel!!!

On the destination side, it is not a major issue as we have emptied the wardrobe and the dust can fall onto the shelf. But the office side (which is where the wire is at the moment, has all the office equipment below.

Apart from removing, disconnecting everything, dust sheets, etc, is there a way to drill a hole in plasterboard that does not send dust everywhere? I've seen vids on a small, drill-bit hole but not 10cms. Of course, I would use a vac but that is challenging with 10 cms. Perhaps a padsaw?

Your thoughts appreciated.

Thanks

Rex

Wallpaper onto lime plaster

WillInAberdeen — Tue, 28 Jul 2026 11:17:41 +0100

How soon can you wallpaper onto fresh lime plaster, does it need specific wallpaper paste, anything I should know about it?

I put breathable wood-fibre IWI with Lime Green Solo plaster on the external stone wall of a room, and want to hang plain lining paper (no vinyl) to match the existing finish on the other internal walls. I will paint the lining paper with some breathable paint, probably Earthborn.

Lime Green say they don't recommend wallpapering their plaster but didn't explain why.

ISTM that lime plaster walls have traditionally been wallpapered for 100s of years including in my house, so not sure what the issues might come up?

Home Energy Model

djh — Fri, 15 Dec 2023 09:32:39 +0000

Will in Aberdeen spotted the Home Energy Model initiative: https://www.gov.uk/government/consultations/home-energy-model-replacement-for-the-standard-assessment-procedure-sap but can't start an appropriate thread. So here is one.

Oak Frame, Oak Sarking, Roof Insulation

DrewWiley — Thu, 23 Jul 2026 18:04:13 +0100

I have been building an Oak framed out building for a number of years for use all year round, it is 10mx5m. It will have a heated floor.

On the inside Its open oak rafters, then oak square edge sarking with 3mm spacing using random sized boards. I dont want any insulation on the inside of the building as it looks lovely inside.

Externally i dont want any soffits or fascias just open rafters and perlin ends.

My dilema is insulating the roof, my initial thought is as follows

the sarking is pretty flat however not perfectly flat.

Rafters are 80mm so on top of the sarking lay a vapour membrane (i need to this to be black as i will see it through the sarking gaps inside) ill then screw using stainless spax washer heads a 80mm wide, 50mm deep oak battens on top of the rafters (externally). i will then use kingspan 50mm k107 in between each of these new battens (from the ridge to the end of roof). then my normal roofing approach counter batten with draping roofshield followed by pantiles. Would this be a suitable approach?

I would need to use an oak batten running the length of the roof that is 50mm tall to stop the insulation sliding down and providing a more decorative finish.

This all sounds like a mix between warm and cold.

Any suggestions would be welcome, i did look into TLX Gold etc but wasn't keen.

Or do i simply use something like Solitex Fronta Quattro, then PIR, then counter battens then tiles.

Thanks

Is Hinkley C dead?

SteamyTea — Mon, 07 Mar 2016 18:10:53 +0000

What do people think?

Kitchen worktop replacement

djh — Fri, 15 May 2026 11:42:58 +0100

We're thinking of replacing our kitchen worktops. We have laminate worktops and some of the glue-on end pieces keep coming off and get damaged.

We're considering getting a granite or quartz overlay rather than a full worktop replacement. Does anybody have any experience of these? What's your preference for replacing worktops?

Roof ventilation and summer overheating

wholaa — Fri, 17 Jul 2026 19:42:58 +0100

With the recent hot spell across much of Europe, overheating in homes is back in the headlines. As expected, there's plenty of discussion about air conditioning and the trend towards very large south facing windows, but much less attention seems to be paid to roof ventilation.

I'm not a builder or roofer, so this is a genuine question rather than a statement. It seems to me that relatively few homes have the recommended level of ridge ventilation. Perhaps I'm simply not noticing the more discreet ridge vent systems, but ridge ventilation appears to be much less common than soffit ventilation.

In room in roof houses, particularly where rigid insulation has been poorly installed, could inadequate roof ventilation, especially a lack of ridge ventilation (lacking the stack feect), be a significant contributor to overheating? I'd be interested to hear the views of those with experience in roofing or building physics.

GivEnergy equipment

marsaday — Thu, 16 Jul 2026 12:22:41 +0100

My 4 yo inverter has possibly died. It is not covered by any warranty as GE went bust earlier this year.

I have spoken to the installer and they are looking into my options. They can supply a new inverter I think.

I am pretty poor on understanding the electrics, so if anyone can help me out that will be appreciated.

I think my inverter has failed because I signed up to Axle energy to sell some of my surplus energy. They took control of the inverter on 7th July and I know for a fact the inverter was down from 11th July and has been ever since. I should have checked everything was ok aster the first control event by Axle energy, but I didn't.

Is it likely Axle energy have caused by inverter to die or is it coincidence ?

Eco-friendly Shower tray & enclosure ie low embodied carbon

stonecold — Tue, 14 Jul 2026 20:36:57 +0100

Any suggestions for something with low embodied carbon, or if there is even some line of certification to look for when searching?

I would rather avoid a plastic shower tray unless it's 99+% recycled. Steel is very high embodied energy.

What do all those Carbon Lite home fit? Where do I even start?

Solar irradiance

djh — Mon, 03 Feb 2020 17:30:32 +0000

Does anybody know of a source of solar irradiance data?

Specifically broken into fairly small areas?

I'm trying to forecast how much heat my house needs each day. Apart from the internal and external temperatures, I think the other major factor is solar gain. So I'd like to get hold of records of irradiance over the past year or more and also a 24-hour forecast of irradiance (or longer :)

Historical data I can estimate from my solar generation records but it would be good to have an external source to compare against, and a forecast is the most important bit.

Best Apps for Energy use & PV export monitoring

jms452 — Tue, 06 Jul 2021 11:47:21 +0100

Having recently had a smart meter fitted there are apps out there that can tie into your meter giving you accurate half hourly monitoring without additional hardware.

For example I found an app called Octopus Compare that I can code to my smart meter and look at what different tariffs would cost me. I can also see from the Octopus dashboard my usage and export in half hourly blocks so this data should also be available with the right logins.

So there must be some cool apps out there that monitor, advise, correlate but when I search I'm mainly finding proprietary software that talks to specific brand inverters.

Any recommendations?

Skylights, roof windows and clerestory skylights

tony — Mon, 11 Jan 2016 16:22:22 +0000

Roof windows seem to cool rooms too much.

U values assume steady state and an indoor and out door temperature

But skylights can radiate heat to outer space which is at absolute zero.

This heat loss dominates on any clear night.

Should heat losses from these be reassessed?

Nordan v Allan Brothers

Victorianeco — Fri, 03 Jul 2026 00:04:36 +0100

Any preference even looking at 3G Alu-Clad?

1900s cottage retrofit advice

Charli — Mon, 15 Jun 2026 12:07:43 +0100

Small house- 74m2 over two floors- 2 up 2 down 1900 solid-wall semi. With a large garage (another 30m2) down one side that I want as a 'clean and nominally heated studio/workshop' that needs a new roof. On the right (downstairs) is a very narrow gennel. On the front is the complexity of lots of electrical wiring that will be bureaucratic and probably expensive to move. Uninsulated concrete floor downstairs. Heating is a log burner with boiler- wood is free in money terms, but not in effort (there is a gas supply). South facing roof.

I've got 30K and want a comfortable house with the lowest bills. Happy to DIY almost anything, I'm capable and practical and find it all fascinating.

With a south facing-roof solar pv is worthwhile, can fit 4.2kWp of panels on the roof and there's adjacent south-facing land that I could fit more on. I think that 6kW of panels with excess going to heat dhw will give me largely free hot water for most of the year.

Insulation would be next on my list. 400mm loft insulation is easy.
Garage I'd do a flat or pitched roof with 150mm pir in, and some form of roof lantern/velux. And IWI. The garage has no direct heating and that’s fine.

Need new windows on the north side- pvc triple glazing. The lack of condensation on the windows ever is worth it.

EWI would need the roof extending, the wires moving on the front and I've no idea what to do with the gennel (internally the narrow stairs are there). Would rockwool and lime render play nicely with the 'old houses are always damp' line I keep reading? XPS below dpc? I've no idea how far down the house goes yet- there's unlikely to be much in the way of foundations.
IWI would mean no thermal mass (wfh so in the house all day everyday largely), the kitchen/bathroom would have to wait until those rooms needed some work (I don't want to rip out a perfectly good bathroom for a few years). And the rooms are already tiny- but I could sacrifice enough for 50mm pir. Which is better than nothing, but not inspirational. (Still no idea what to do on the stairs-wall).

Any ideas/inspirational stories/words of warning/things I should go and think/read about?
Many thanks.

AAHP in everyday houses

fostertom — Tue, 30 Jun 2026 09:59:42 +0100

I've reached the point of considering air to air HP (AAHP), maybe with cooling aka AC, as a lowest-intervention solution for boiler-replacement in ordinary small houses (whether 'modern box' or old/rambling cottage) which no one's planning to comprehensively insulate, even incl ones with no existing central heating of any kind.

I need to get up to speed with the varied considerations, like we've gradually learned with wet systems, UFH, ASHP etc. Not least grant aid. Aware of the horrors of 70s/80s cheapo air-heating, and duct-routing issues. And DHW.

Any pointers?

Air Con

Rex — Sun, 28 Jun 2026 13:44:21 +0100

What ho one and all,

There was a recent article in the newspaper regarding the a/c numbers in different countries. Japan (my wife is Japanese) has around 91% domestic a/c installations, the UK, less than 5%.

My wife is really, really keen to get an a/c in our house. 3g, 180mm of Warmcel insulation; I don't think it is going to happen as I'm not drilling large holes through the glazing or walls. She even thanks we could replace one of the 'smaller' glazing panels to accommodate the a/c pipe. No way Jose!!!

Her further research finds this kind of unit: https://nessally.co.uk/ Apparently, according to her, they are very popular and very good. My feeling is, it is all marking hype and a money making scam.

Is there any 'new' technology that makes these portable a/c units as good as the blurb suggests? Are they generally any good or essentially, just an expensive fan that will be in the skip in a few years time?

Grateful for your thoughts and opinions.

Skylights

owlman — Sat, 27 Jun 2026 16:02:43 +0100

I'd like to introduce more natural light into my bungalow living room space approx 8M x 8M. Skylights seemed to be the obvious answer rather than knocking down walls. However, the loft space is of a Fink trussed construction which I can't cut or change.
These large trusses are 70mm x 35mm timber section at 450mm centres and with plenty of length eaves to ridge. I'd seen firms that do long narrow 3g fixed lights for this sort of application. but I'm unsure as to how they'd look from the interior. I'd thought of three in a row on alternate truss spaces with 2 x flat ceiling sections between. It's a pantile roof so flashing detail could get messy. The good news is its N. facing.
Can anyone spot any flaws in my idea? Has anyone attempted skylights in a trussed roof situation and does anyone know of a decent firm who make the lights.

Telegraph Article - Eco rebuild

borpin — Tue, 16 Jun 2026 12:03:45 +0100

Not sure if this link will work, but this is a really good looking house IMHO.

https://www.telegraph.co.uk/gift/c79c96400f3a8bff
https://www.telegraph.co.uk/money/net-zero/i-spent-900000-creating-the-ultimate-eco-home/

One thing I noted is that he is funneling his MVHR extract into a 'cupboard' around the Heatpump. That sounds like an excellent idea.

Batteries

djh — Fri, 08 May 2026 17:57:27 +0100

What's the state of play with batteries these days?

I am generally aware of the 'big' batteries supplied by the likes of Tesla, Fox ESS etc

There now also seem to be much smaller products aimed at the 'balcony solar' market and I don't know anywhere near as much about them :cry: So ...

(1) are they actually legal and what regulations apply?
(2) does anybody know which ones are good and which ones to avoid?
(3) a lot are aimed at integrating with balcony solar, but I already have solar on my roof with microinverters, so I just want an AC connected battery. Does that change things?
(4) how are they controlled - which require cloud or other external connections and which can be controlled locally somehow?

I'm sure I'll think of some more questions, but that'll do for now! :bigsmile:

(AI) data centres, water, geo

minisaurus — Sat, 06 Jun 2026 08:22:14 +0100

I’m surprised water consumption by data centres is an issue. Presumably, in countries with at least half-functioning planning systems, a centre could be forced to 1) use geo energy for primary cooling, and 2) build a closed circuit water circulation (with filtration) system for the needed-in-summer cooling fans, with a restriction on the amount of drinking water the centre be allowed to use per annum?

My workplace - large hospital - achieves all cooling needs using geo energy - approx 100 holes approx 70m depth. We even heat space & water (almost) year round using same energy & some extra electricity to get the temp up from 40C to 68C

If I wanted to build a data centre, I’d do this.

However, I don’t want to build one :)

Finally finished all the eco energy improvements! De-carbonized 190 year old house!

stonecold — Mon, 15 Jun 2026 03:08:20 +0100

Its finally finished!

The house is no longer stone cold, damp, with slugs getting in. It's warm, comfortable and the bills have dropped loads.

Since the planning started 4 years ago we have FINALLY got the last job done!

Here's the main jobs done
- LPG cooker with non-fan oven ?? induction hob and electric fan oven
- Oil boiler and immersion heater ?? Heat pump and central heating refit
- Solar PV ? with large battery, and gateway for off-grid
- EV charger
- Solid wall insulation - Diathonite lime/cork EWI - from 2.0U to 0.60U
- Triple glazed timber/alu - all but 2 windows, 3 doors
- Raised concrete patio bridging damp course ?? lowered porcelain patio tiles
- MVHR and removed bathroom and kitchen extractors, recirculating cooker hood
- Wood and recycled supasoft loft insulation top-up
- All light fittings now use replaceable LED bilbs ?

oh and we needed a new roof!

Thank you to everyone for their suggestions and answering so many questions. I'm so glad GBF is still here - I can't remember who is currently running things but many thanks! There's nowhere similar. :cool::cool::cool:

No doubt I will still post since there are other important repairs needing doing plus some accessibility improvements, I'm hoping to get eco-friendly stuff for. :cool: