Green Building Forum - How would you insulate this building conversion? ideas please... Tue, 19 Dec 2023 08:31:41 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301600#Comment_301600 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301600#Comment_301600 Mon, 15 May 2023 22:26:50 +0100 Dominic Cooney As a long time GBF member I would have liked to externally insulate, but this isn't going to happen for various reasons. So this leaves internal insulation.
We would like to achieve Passive House levels of insulation and airtightness.
The existing concrete floor will have to come up and be dug out, EPS in the floor should be straightforward.
But what to do with the walls and roof?
Considerations so far include I-beams for the walls with either EPS or rockwool between. Would we need to leave a cavity between this and the existing structure? Drained? OSB for racking, with a membrane facing the cavity?
We quite fancy OSB as the internal face, to avoid plasterboard and skimming. All services could be surface mounted for an industrial feel and for ease of alteration in future. I expect we may need a sprinkler system due to open plan kitchen, dining, lounge etc?
I have been playing about with U-values, which is easy enough, but I'm struggling with the finer points of construction details.

The GBF hive mind is powerful and varied, so any ideas or suggestions would be gratefully received.]]> How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301601#Comment_301601 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301601#Comment_301601 Mon, 15 May 2023 22:31:54 +0100 Dominic Cooney How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301602#Comment_301602 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301602#Comment_301602 Mon, 15 May 2023 22:36:26 +0100 Dominic Cooney How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301603#Comment_301603 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301603#Comment_301603 Mon, 15 May 2023 22:37:00 +0100 Dominic Cooney How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301604#Comment_301604 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301604#Comment_301604 Mon, 15 May 2023 23:58:07 +0100 Viking House How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301606#Comment_301606 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301606#Comment_301606 Tue, 16 May 2023 07:03:12 +0100 Dominic Cooney That sounds like it would be cheaper than I-beams and Rockwool?
What do you think about the interface with the concrete block walls? I guess I could use tanking slurry on the inside face of the block for waterproofing. Ply lining boxes to window reveals.]]> How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301607#Comment_301607 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301607#Comment_301607 Tue, 16 May 2023 08:36:35 +0100 GreenPaddy
- keep the internal conc slab, and build on top. Raise the external ground locally at the front, breaking out some of that concrete apron, to allow planting, softening the frontage visually, and allowing gentle ramps to bring you to the slightly higher internal FFL. The side entrance is stepped anyway, so a couple more steps may not matter. Add some raised beds for planting along the side elevations to disguise this level diff, and again visually soften. This may also help with issues with DPC's or lack of them around the structure. Your wet services are all around the perimeter, so should get drain falls in insulation depth, without cutting into exist slab too much. Big cost and carbon saving, keeping all that concrete.

- demolish the dwarf block wall, so it's no longer a constraint. You're over-cladding anyway, so it's not part of the visual conservation. Maybe leave the bottom course (or whatever height), to give you the underbuild structure to set the internal frame on, so it is then of use, rather than something to compromise your design. It then becomes more like a simple, typical timber frame construction. The internal frame can be of whatever build-up you prefer. You then have a choice, not forced down a route.

- I suspect the roof will be a trickier problem than the walls, assuming you keep he original structure, and build inside it, with a thermal layer (similar to the approach for the walls). Maybe a light weight metal stud to carry the insulation and internal surface finish? Are there solar panels planned? Additional load onto the existing roof? Could add a couple of posts, say hidden in the bedroom wall, to give additional roof ridge support if needed.

- OSB internally and timber cladding externally with adjacent buildings... remember fire spread regs. You'll likely need to treat all those surfaces with a fire retardant to meet the approp Euro Class. BSO's are super hot on anything fire related, (post Grenfell). With no supported floors, you don't have any "elements of structure", so that makes it a bit less arduous perhaps.

I'd start drawing out some sections at various junctions/interfaces, to clarify what you currently have. That makes the issues more obvious, and so will help formulate solutions.]]> How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301608#Comment_301608 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301608#Comment_301608 Tue, 16 May 2023 09:00:42 +0100 Dominic Cooney
Posted By: GreenPaddyYou're over-cladding anyway, so it's not part of the visual conservation.


I should have clarified - we are leaving the exterior as it is now, because SWMBO actually likes how it looks and wants to keep it exactly the same. The plans shown are from my dreams of EWI and reclad using the same timber (but with a bit extra) which are now sadly shattered.]]> How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301609#Comment_301609 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301609#Comment_301609 Tue, 16 May 2023 09:05:12 +0100 Dominic Cooney How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301610#Comment_301610 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301610#Comment_301610 Tue, 16 May 2023 09:07:36 +0100 Dominic Cooney How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301611#Comment_301611 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301611#Comment_301611 Tue, 16 May 2023 09:12:15 +0100 Dominic Cooney How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301612#Comment_301612 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301612#Comment_301612 Tue, 16 May 2023 09:44:25 +0100 WillInAberdeen
Our options seem to be a) build a separate watertight/insulated building, standing just inside the extg structure, but relying on none of the existing elements; or b) knock it down and start again.

A housing development down the road has done b), clearing the site and then building new houses to the original dimensions, clad in high-spec timber and profiled steel to give an impression of a steel farm shed, but watertight. This suggests that b) was their cheapest option, though I doubt they thought about embodied carbon.

There are a lot of bats and a family of owls who would need to be rehomed.

Edit: the steel frame is a thermal bridge too.]]> How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301613#Comment_301613 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301613#Comment_301613 Tue, 16 May 2023 10:28:59 +0100 Dominic Cooney Posted By: WillInAberdeenthe steel frame is a thermal bridge too.

which is why I wanted to externally insulate and carry it on down to include the foundations. Tea cosy.
We could have then had the steel frame exposed on the inside, and extended the concrete block walls upwards to provide thermal mass inside the heated envelope.]]> How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301616#Comment_301616 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301616#Comment_301616 Tue, 16 May 2023 10:57:27 +0100 djh Posted By: Dominic CooneyBut what to do with the walls and roof?
Considerations so far include I-beams for the walls with either EPS or rockwool between. Would we need to leave a cavity between this and the existing structure? Drained?As others have identified, the existing outer timber etc becomes the mainly waterproof layer. Inside that you'll need a drainage plane - probably a membrane - and then a separate thermal, airtight structure inside that. I-beam, Larsen truss, whatever. SIP if you can get them in?

Knock it down and rebuild may well be cheapest due to the VAT rules.]]> How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301620#Comment_301620 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301620#Comment_301620 Tue, 16 May 2023 11:40:32 +0100 Dominic Cooney How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301621#Comment_301621 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301621#Comment_301621 Tue, 16 May 2023 12:11:12 +0100 WillInAberdeen
You can see daylight through that kind of wall cladding - treat it as 'decorative' but in no way weather resisting - it's designed to keep cows very much 'ventilated'!

Suggest to remove and store the cladding, remove the roof, build a new timber building within the steel frame while you have access all round? The inner building should have a waterproof external layer needing no maintenance, perhaps rendered EWI. Then treat the stored cladding and fasten it back onto the steel frame outside (but not connected to) your new building.

Edit: after living somewhere for a while, we all tend to feel a mental attachment to 'what is already there' and seek to improve it, it is more difficult to get our heads around replacing it. There's probably a psychological term for this! In many cases that is good for carbon and cost.

However, steel farm sheds are deliberately very low cost and low quality structures. To become houses, they need such a lot of upgrading and the reusable bits are such a low % of the total project value, that it might well be worth thinking again about rebuilding from scratch, and then making it look sufficiently like the original to keep the planners and your co-owner happy?

This discussion is helpful for our thoughts about what to do with our own shed, so please keep sharing your thinking!]]> How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301623#Comment_301623 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301623#Comment_301623 Tue, 16 May 2023 13:03:47 +0100 Doubting_Thomas
Posted By: Dominic CooneyWe quite fancy OSB as the internal face, to avoid plasterboard and skimming. All services could be surface mounted for an industrial feel and for ease of alteration in future.


Bear in mind surface spread of flame restrictions. We have Cross Laminated Timber frame which we wanted to expose internally on walls and ceilings. The Building Regs required that we coat it all with a flame retardant finish and I eventually found a nice translucent treatment (NT Deco by Nordtreat) which looks like limewash.

I actually prefer the finish to the bare timber now, but just remember to budget for the painting. That aspect isn't a saving on plasterboard (although you do of course save on the skimming etc.)

The other anecdotal advice is that whilst it does mean you can mount pictures and shelves on walls fairly easily and with confidence (unlike the paper thin plasterboard most developers use), you then can't fill the holes so easily if things move. There are wood fillers of course, but so much of the DIY market is geared to white plasterboard walls that it's quite eye opening when you don't have them!

Posted By: Dominic CooneyConsiderations so far include I-beams for the walls with either EPS or rockwool between. Would we need to leave a cavity between this and the existing structure? Drained? OSB for racking, with a membrane facing the cavity?


We used the timber I-beam method to overclad our frame, with OSB on the outside as racking and support for waterproof membrane. Comparatively it was v. cheap and reasonably straightforward. Note that the flange and web shape of the beams means there is a risk of voids at the inner and outer edges if you just use standard insulation batts, so we chose our thicknesses to match the different 'layers' of the beam e.g. our total insulation thickness was 400mm but that was a layer of 50mm between the outer flanges, 300mm between the webs and then another 50mm on the inner flanges. This meant each layer could compress to fill its relative width. Possibly overkill but it resulted in a very good flush fit.

You'll need EPS for at least the bottom 150mm 'below DPC', but comparatively this was a lot harder to fit tightly. We staggered joints etc. but you really want to foam glue the edges as you go too.]]> How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301624#Comment_301624 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301624#Comment_301624 Tue, 16 May 2023 13:44:20 +0100 Dominic Cooney How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301626#Comment_301626 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301626#Comment_301626 Tue, 16 May 2023 13:57:16 +0100 Doubting_Thomas
I also just spotted this write-up of a passivhaus barn conversion project. Page 38 onwards. Sounds exactly like what you want to do:

https://passivehouseplus.co.uk/issuu/uk-edition]]> How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301627#Comment_301627 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301627#Comment_301627 Tue, 16 May 2023 13:58:01 +0100 Dominic Cooney
any observations gratefully received.]]> How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301628#Comment_301628 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301628#Comment_301628 Tue, 16 May 2023 14:00:09 +0100 Dominic Cooney How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301629#Comment_301629 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301629#Comment_301629 Tue, 16 May 2023 14:05:01 +0100 Dominic Cooney Posted By: Doubting_ThomasSounds exactly like what you want to do

Great link thanks, I will have a read in more detail. This is the one my friend has seen and suggested the I-beam construction inside the exisitng shell.]]> How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301630#Comment_301630 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301630#Comment_301630 Tue, 16 May 2023 15:12:53 +0100 djh Posted By: WillInAberdeenYou can see daylight through that kind of wall cladding - treat it as 'decorative' but in no way weather resisting - it's designed to keep cows very much 'ventilated'!In a balanced rainscreen it is the inner drainage plane that needs to be waterproof. Probably a membrane in this case. The outer screen intercepts some of the rain and slows the rest via pressure effects.]]> How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301631#Comment_301631 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301631#Comment_301631 Tue, 16 May 2023 16:52:28 +0100 WillInAberdeen
Whereas cows like lots of draughts through cowshed walls to keep them healthy.

The offices I mentioned are in our agri shed, have a stud wall with a membrane facing the original dwarf wall and cladding across a cavity. It is apparent that the membrane is leaking, possibly due to debris in the cavity, or the efforts of birds/mice. But the membrane is inaccessible to maintain, so I recommend a no-maintenance waterproof layer on the outside of the 'inner box'.

The article in PH+ has the right idea, build a separate new building inside the existing one 'a box inside a box'.]]> How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301632#Comment_301632 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301632#Comment_301632 Tue, 16 May 2023 17:54:04 +0100 Dominic Cooney Posted By: WillInAberdeenno-maintenance waterproof layer on the outside of the 'inner box'.

I wonder if this could be tanking slurry on the inner face of the concrete block walls? increase their height up to eaves level so that the vertical timber boarding is just decorative. It could even have a roofing type membrane behind it to help shed driving rain that gets through the gaps.]]> How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301642#Comment_301642 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301642#Comment_301642 Tue, 16 May 2023 20:35:25 +0100 djh Posted By: WillInAberdeenIndeed, but the outer screen is intended to keep UV light off the inner screen and exclude insects, bits of dead leaves, etc, from the cavity - so if you looked through the open door in the OP pic, you ideally shouldn't be able to see any daylight through the far end of the building!Sorry, but that's simply not right. Keeping UV out is necessary iff the drainage plane is UV-sensitive, sure, but that's not a given. Keeping insects and leaves out should be done by a separate insect mesh if needed. Insects will get through pretty much any timber cladding, since joints need to be open to allow for movement of the timber.

See e.g. the pictures at https://www.russwood.co.uk/blog/timber-open-rainscreen-cladding-the-ultimate-guide-to-detailing/ or read the wikipedia rainscreen article.]]> How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301643#Comment_301643 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301643#Comment_301643 Tue, 16 May 2023 21:03:46 +0100 WillInAberdeen
Edit: post deleted as this is going OT. Just treat the existing cladding as decorative and put a no-maintenance beastie-proof waterproof outside layer on the new building within the barn.]]> How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301672#Comment_301672 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301672#Comment_301672 Sat, 20 May 2023 18:33:45 +0100 Viking House Posted By: Dominic CooneyThanks for the suggestion VH
That sounds like it would be cheaper than I-beams and Rockwool?
What do you think about the interface with the concrete block walls? I guess I could use tanking slurry on the inside face of the block for waterproofing. Ply lining boxes to window reveals.If the block wall isn't letting in water you could leave it be, pumping the void with EPS beads would be more resistant than Cellulose and may eliminate the need to plaster the external wall, a perimeter french drain around is always good.]]> How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301673#Comment_301673 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301673#Comment_301673 Sat, 20 May 2023 18:41:28 +0100 Dominic Cooney Posted By: Viking Housepumping the void with EPS beads

Would beads normally be cheaper than solid slabs of EPS for the same volume?]]> How would you insulate this building conversion? ideas please... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301674#Comment_301674 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17842&Focus=301674#Comment_301674 Sat, 20 May 2023 18:42:49 +0100 Dominic Cooney Posted By: Viking Housea perimeter french drain around

Also a good idea and was hoping to do this.]]>