My solar and batts

[BISFBath]

It’s a BISF house

Concrete bottom half, steel top half some not too far away from me

Yeah the concrete is a render on steel mesh stretched over steel laths, an industrial version of lath and plaster. Many people seem to think it was cast either in situ or precast, but it is actually a render. If you strip the drylining in renovations, you can see how the render was roughly smoothed on the back with a trowel. It's only about 50mm thick. Pretty interesting I think, I don't know if that was used elsewhere.

[Mr Gus]

Thanks for the reminder, it puts it into perspective, I also lived in a victorian house, which was cold, I need to think harder that these were likely similar in terms of heat retention (bad but not awful because there was little to compare with)

How do folk / councils deal with exterior insulation modernisation? I guess random drilling is a no no so is stuff stuck on with an adhesive layer like some EWI then overclad? ..sorry, your house construction is a bit of a rare opportunity.

[BISFBath]

Thanks for the reminder, it puts it into perspective, I also lived in a victorian house, which was cold, I need to think harder that these were likely similar in terms of heat retention (bad but not awful because there was little to compare with)

How do folk / councils deal with exterior insulation modernisation? I guess random drilling is a no no so is stuff stuck on with an adhesive layer like some EWI then overclad? ..sorry, your house construction is a bit of a rare opportunity.

That's ok, I'm quite nerdy about it! Usually something like 100mm polystyrene insulation is applied with the normal fixings. You can screw into the steel cladding upstairs and the render downstairs. Then an acrylic render is applied. Alternatively if the aim is just ease of maintenance rather than insulation, timber battens are applied vertically and then PVC cladding horizontally.

I'm actually quite skeptical of how effective EWI is on a BISF house as there is a large ventilated cavity in the walls open to the loft. You can put your arm down into the cavity from the loft easily. The original outer layer is basically just a rainscreen, then there is a cavity containing the steel frame and then on the inside is the dry lining with fibreglass insulation nailed to the back.

So if you apply EWI I think you've still got a big cavity full of "outside" air with just the original plasterboard and thin layer of fibreglass between the interior and that "outside" air. Ie it seems as though the EWI is mostly bypassed.

I think part of the problem is that everything that isn't cavity wall suitable for CWI insulation gets lumped together as "solid wall" but in this case it's even more of a cavity wall than a traditional cavity wall. If that makes sense?

[Mr Gus]

It does indeed, I was watching assembly of a group fo seven fag smoking builders constructing one house just the other week, some anniversary of the design/ designer I think.

Wonder what the housing stock numbers are for this sort of pre-fab build & what the councils (who have the plans) consult to assist the net zero (blah blah) numbers being reached, as this must be solvable (hopefully not as stupid as the rubber wallpaper suggestions of the last 20 odd years they put out.

[BISFBath]

It does indeed, I was watching assembly of a group fo seven fag smoking builders constructing one house just the other week, some anniversary of the design/ designer I think.

Wonder what the housing stock numbers are for this sort of pre-fab build & what the councils (who have the plans) consult to assist the net zero (blah blah) numbers being reached, as this must be solvable (hopefully not as stupid as the rubber wallpaper suggestions of the last 20 odd years they put out.

From memory about 30,000 were built so depending on how you look at it, not many out of the total housing stock, or quite a lot of originally practically identical houses. Usually there are a fair number in any one location though.

I'd be more worried about the pre-cavity masonry houses as there are a lot more of them and they often have features that make them hard to treat like no/minimal roof overhang, bay windows and kitchens/bathrooms sticking out, people are often reluctant to change the external appearance etc. I did see an interesting video about how in the Netherlands they're manufacturing entire insulated facades and roof units to put over older houses... But that's another storey.

[Mr Gus]

Links are great if / when you have the time

Rejuvenation of housing stock is vital.

[BISFBath]

Links are great if / when you have the time

Rejuvenation of housing stock is vital.

I'll try and dig some out. In the meantime here I some I took and and a historic photo of construction.



Here's the wall lining board removed. You can see there is a 'duvet' of glassfibre in brown paper nailed to the back of pre-made panels that were then attached to the steel frame.



Old insulation stripped out so you can see the steel frame and back of the external cladding.



New insulation and framework. I'd only just started here. Later it's at least half expanding foam



Insulation infill



Ceiling down, you can see how the first floor is made of timber noggins slotted into steel I-beams. Pretty neat as it doesn't need two layers. Also how the internal walls are non-structural.



Old photo showing just the frame when a house was under construction. It's pretty lightweight because there isn't any masonry to support. You can see numbers painted on the steel, I think these were to show what went where during assembly because all the steels arrived separately. Pre-fabricated is not really accurate.

[Joeboy]

OK I'll bite. Why no airgap between batteries and why are they not rotated thru 90 clockwise from above to reduce cable runs and easier access to batteries/terminals? As to the loftboards repurposing....OK, not great BUT, why didn't you install a mounting board yourself if you knew they were coming?

Not too hard to retro work to a better look/spec/passive cooling.

Looks like a fine generation day and that is what really counts. How much are you generating on a decent day?

Orientation of the batts is my fault, I moved them when insulating and putting the loft boards down, so I can easily shift them apart.

I would have installed a mounting board if I'd suspected they'd be such bodgers. But I'd maybe naively assumed they'd do it properly. Next to it the boiler installer used a piece of OSB which seemed like the proper way to do it. I just assumed they'd do the same.

It's been an almost perfectly clear day here today, generated 30.5 kWh.

I would separate the batteries by an inch or so.and also place them on wooden strips to allow all six sides passive airflow. Also worth keeping an eye on battery temps if this is year one of the install in the loft.

That's a good daily generation figure, well done!

[Mr Gus]

Interesting renovation, well done sir! what does it bring you up to in terms of perceived insulation values as per the packet from /to?

[BISFBath]

Interesting renovation, well done sir! what does it bring you up to in terms of perceived insulation values as per the packet from /to?

Thanks! I did some calculations, but it was a while ago so I can't remember now. How useful they'd be I don't know as the insulation layers aren't continuous, though I've tried to overlap them. Basically i've got ~65 mm of PIR slotted into the steel uprights, then 50 mm infill in the new studwork lining in front of that. In the loft I've got ~100 mm of fleece type insulation between the noggins and 50 mm of expanded polystyrene on top so I could put loft boards down over the whole thing.

It has made the place noticeably more comfortable and less draughty. Removing the chimney and gas fire and the air vent that went with it helped too.