Spray foam on cold bridge steels

[Great_scot_selfbuild]

13 minutes ago, Nickfromwales said:

Use 20mm Compacfoam to do this

@Nickfromwales it looks like compacfoam is an alternative to the aerogel(?). This prompts two questions for me:

1. How do you fix it to the smooth steel column? (I understood @Super_Paulie‘s comment to imply they used a foam as an adhesive - I was picturing something like the foam glue used on my caberdek boards by the installers).

2. Have you used both aerogel and compacfoam? Why opt for compacfoam? (Not a challenge, just understanding why)

 

17 minutes ago, Nickfromwales said:

especially if the steel is not thermally broken where it meets the foundation

Thankfully this was where I ensured we got a good quality (50mm) thermal break underneath the column - something I spotted as being omitted from the design.

 

[Super_Paulie]

2 hours ago, Great_scot_selfbuild said:

@Super_Paulie are you saying you attached the aerogel with foam?

 

I have a similar vertical steel column that needs wrapping on the outside (it’s a corner post between two full-height windows). 

mine was the inside face, flush with the block. I attached a 10mm aerogel with spray adhesive and them foamed the edges to the block. Finally covered in plasterboard when i did the full wall, avoiding a join at that point. Seems to have worked, no noticeable cold spots here and previously the steel was absolutely freezing. 

[JohnMo]

1 minute ago, Great_scot_selfbuild said:

compacfoam is an alternative to the aerogel

They are very different materials, aerogel is a fibrous soft material, compacfoam, is a solid EPS, looks EPS but rock like. You can drill it screw into it etc. treat it more like wood than insulation. So fixing self drilling screws direct through compacfoam into the steel. Then if you wanted plasterboard screw into to the compacfoam or foam into position.

 

Aerogel I bought it but I ended up using PIR, but @Nickfromwales suggestion of compacfoam is way better. We did upstands for our roof lights with it, easy to use

[Nickfromwales]

6 minutes ago, JohnMo said:

They are very different materials, aerogel is a fibrous soft material, compacfoam, is a solid EPS, looks EPS but rock like. You can drill it screw into it etc. treat it more like wood than insulation. So fixing self drilling screws direct through compacfoam into the steel. Then if you wanted plasterboard screw into to the compacfoam or foam into position.

 

Aerogel I bought it but I ended up using PIR, but @Nickfromwales suggestion of compacfoam is way better. We did upstands for our roof lights with it, easy to use

It’s bloody good stuff tbf. 
 

I don’t recommend screwing it on, I used CT1, 100% coverage, spread thinly, and clamped with a 4x2 splint until cured so it didn’t move. 
 

Sealed 360° around it to kill off any risk of cold air convecting up behind / around it, and worked like a dream. 
 

RAL colour coated Alu profiles were then made bespoke to go on the outside, to butt up to, and match identically, the window frames etc.

 

Looked totally factory when done. 👍 

[Great_scot_selfbuild]

4 hours ago, Nickfromwales said:

RAL colour coated Alu profiles were then made bespoke to go on the outside, to butt up to, and match identically, the window frames etc.

@Nickfromwales I’m trying to picture this but struggling - do you have a photo you could share?

 

I’d be using it externally, as well as possibly internally (though internally I imagine I have more options available to me). Was this alu profile a complete covering or just on the edges to butt up against the window?

 

@JohnMo @Nickfromwales any recommended suppliers of compacfoam? It looks muck easier to work with than aerogel. 

 

[Nickfromwales]

21 hours ago, Great_scot_selfbuild said:

@Nickfromwales I’m trying to picture this but struggling - do you have a photo you could share?

 

I’d be using it externally, as well as possibly internally (though internally I imagine I have more options available to me). Was this alu profile a complete covering or just on the edges to butt up against the window?

 

@JohnMo @Nickfromwales any recommended suppliers of compacfoam? It looks muck easier to work with than aerogel. 

 

21° (formerly The Green Build Store) stock it in very odd sized (annoyingly so) strips.

 

I lost loads of pics due to an iCloud feck up so none of that job.

 

Basically just powder coated aluminium panels, cut and bent to form full height cladding. Very simple. 
 

I can give you details of the guy that did these at a Leicester project for me if you like? Just PM me if so. 

[Great_scot_selfbuild]

9 hours ago, Nickfromwales said:

21° (formerly The Green Build Store) stock it in very odd sized (annoyingly so) strips.

 

I lost loads of pics due to an iCloud feck up so none of that job.

 

Basically just powder coated aluminium panels, cut and bent to form full height cladding. Very simple. 
 

I can give you details of the guy that did these at a Leicester project for me if you like? Just PM me if so. 

I’m likely to just cladding timber the same as the rest of the build. 

[Nickfromwales]

34 minutes ago, Great_scot_selfbuild said:

I’m likely to just cladding timber the same as the rest of the build. 

I'd defo still insulate to some degree, maybe just 6mm or 10mm Marmox boards, to get the steel isolated as best as practicable. Cost is negligible, results far better.

 

CT1 the Marmox on, to clean, decontaminated red oxide or liquid DPM, and then you can bond the timber to the Marmox for a face-fixing-free finish with zero cold bridging.

[Great_scot_selfbuild]

54 minutes ago, Nickfromwales said:

CT1 the Marmox on, to clean, decontaminated red oxide or liquid DPM, and then you can bond the timber to the Marmox for a face-fixing-free finish with zero cold bridging.

Will definitely still be insulating to some degree - just with our board & batten or our timber shingle, but it'll still need an air gap behind it. The steel has already been zinc oxide coated and then bitumen painted on top prior to the windows being installed. Finish has come up well in terms of protecting the steel (these paint layers were specified by the SE to match the protection on the steel ring beam).

[Nickfromwales]

1 minute ago, Great_scot_selfbuild said:

but it'll still need an air gap behind it

For just at the column? I'd say not.

[Great_scot_selfbuild]

6 minutes ago, Nickfromwales said:

For just at the column? I'd say not.

Why not? surely the same principle applies to it getting damp / soaked and needing to be able to dry out? both Board & batten and shingle involves overlapping timbers which I understood would need the airflow to avoid mould. I know the area is small (250 x 250) but they're at the corners of the house and will take all the weather.

[Nickfromwales]

5 minutes ago, Great_scot_selfbuild said:

Why not? surely the same principle applies to it getting damp / soaked and needing to be able to dry out? both Board & batten and shingle involves overlapping timbers which I understood would need the airflow to avoid mould. I know the area is small (250 x 250) but they're at the corners of the house and will take all the weather.

Based on what it's attached to, in such limited amount, basically.

 

Provide a substrate that wont degrade, is impervious to moisture and movement, decouple them with a few mm of suitable mastic, and I don't see an issue.

 

Happy for someone to tell me otherwise of course.