Kentish RenoExtension

Illbruck ME500e with a butyl adhesive will do the job, I would also use Illbruck TP600 around the frame of the window.

 

I would have used llbruck PR007 for the window installation.

 

 

 

Looking good though, good job.

Edited September 18, 2017 by craig

Thanks for this.

 

What's wrong with the plywood box method in your view?

 

I also found this: 

 

(Advance to 3:15)

 

Here they use something called Compacfoam that the window sits on, instead of the bottom brackets.

Edited September 20, 2017 by gravelld

6 minutes ago, gravelld said:

Thanks for this.

 

What's wrong with the plywood box method in your view?

 

Here they use something called Compacfoam that the window sits on, instead of the bottom brackets.

 

Plywood method is fine, but insulation-wise would be worse over brackets and EWI sitting snugly against the frame.

 

Not seen the Compactfoam option, but that looks like a decent method also. Not sure how supportive that would be with some larger/heavier windows (>400kg) though.

Did you do the TB analysis for comparing the brackets with frame? Plywood's lambda is a lot lower than that metal's... Just wondering.

Each window frame only has a few brackets (depending on weight/size etc), so no, I did not do any calcs, just figured that I would be needing more than plywood to keep some of my windows in place. All of the metal fixings would also be completely be surround by insulation so minimal bridging in these particular locations. The other advantages with the mechanical fixings is that you can alter the x,y,z positions in case of last minute adjustments with the window frame.

The Compacfoam is the best option and can easily support the weight but is very expensive. I've also seen fibreglass angles used. I like the idea of the brackets but was afraid they wouldn't be strong enough to support the weight. I personally used galvanised steel angles at the bottom and restrained the window back to the existing blockwork with steel brackets as I didn't know better at the time. Live and learn. If I was doing it again I'd use the Compacfoam

 

 

 

That's a meaty looking bit of steel at the bottom. At least you know it's not going to move easily. Next time I'll look at Compacfoam also, since my bracketry came to just under £800 in any case.

Thanks @Dudda interesting to hear more opinions on the Compacfoam option. My understanding is it's very rigid.

It is indeed very rigid. It's essentially like a piece of timber. I've just used my first bit under the front door, and am planning to use some more for the EWI windows as in this thread

I've also just done the calculation comparing 100x75 compacfoam batten, 50x50 timber batten and 6 off 3mm thick stainless and galv brackets 80mm wide. This is fitting a U=0.92 PVC+ali frame into 160mm of pavatex woodfibre, so Wall U is 0.19. I used Therm for the sums (which is a very annoying piece of software!).

Psi values:

compacfoam: 0.008 W/mK

timber :     0.014

galv bracket: 0.041

Stainless bracket 0.036

 

However as the brackets are only 11% of the length the average psi is:

galv: 0.012

stainless: 0.011

 

So compacfoam is best, but metal brackets are fine too so long as the frames are well-lapped with insulation. Stainless brackets seem surprsignly expensive.

Cost is

£10.80 galv brackets (90x90x62)

£ 46.44 Stainless brackets

£ 28.90 1m compacfoam  (6 x 166mm sections). So it's not really that expensive. It is if you line the whole window perimeter with it, but you might as well just fit the load-bearing blocks, then put EPS between them. You could use 1.5m with a 1m piece across the bottom and 4 blocks up the sides. That'd be £44.85. per window.

 

This is the 'line all round the edge method by the suppliers: https://www.youtube.com/watch?v=5sSKsKB9doc

This is the 'use blocks' method: https://www.youtube.com/watch?v=GUUrd7dbBzU

 

 

 

 

Hi Wookey, welcome.

Useful links Wookey. What are these blocks shown at 37 secs ? How is the compacfoam attached to the bracket?

https://youtu.be/GUUrd7dbBzU?t=37

 

I had just thought of bracketing a sill of compacfoam or foamglas to support the weight like this

 

 

 

I got a sample of compacfoam, and whilst being quite solid, i wouldn't trust it with a very heavy window. I think its intended purpose was for beneath doors really where there is a firm bearing underneath it.

 

For me, either steel angles like this, or proper timber

Dont worry about how good compact foam is in compression. If we are putting a machine on a delicate floor we use compact foam under the outrigger pads. 400mmx400mm foam pads will support 3 tons no problem.