Windows are doing my head in (and not Microsoft for once)

[Reiver]

Now then, to start with I must confess to being a complete newcomer to window specification and installation, so please forgive me if I ask anything that's obvious. As mentioned previously I'm considering an ICF build and I'm trying to work out which windows will look and work the best hopefully without breaking the bank - I never realised the things could be so expensive!. So my first queries are:

1) How far in/out should the window sit in the aperture? Logic tells me that the line of the glass should be over the junction of the outer (thick) insulation and the concrete pour, but is that right?

2) It looks like splayed reveals could be a good idea as I'm leaning towards some that are tall & narrow and that approach does seem to let more light in as well as giving a wider field of view - this is an interesting link: https://www.new-learn.info/packages/tareb/dynamic/docs/splayed_reveals.html

So what's the best way to do splayed reveals with ICF? - chopping corners off the blocks is obviously going to result in a nasty mess when pouring, so it looks like oversizing the apertures then building in some angled sections - but what would be acceptable to BC from the thermal point of view? Thanks!

[Mr Punter]

1) Normally line the glass up to the centre of the insulation.

 

2) How to do this depends on the ICF and the external finish.

[nod]

10 minutes ago, Reiver said:

Now then, to start with I must confess to being a complete newcomer to window specification and installation, so please forgive me if I ask anything that's obvious. As mentioned previously I'm considering an ICF build and I'm trying to work out which windows will look and work the best hopefully without breaking the bank - I never realised the things could be so expensive!. So my first queries are:

1) How far in/out should the window sit in the aperture? Logic tells me that the line of the glass should be over the junction of the outer (thick) insulation and the concrete pour, but is that right?

2) It looks like splayed reveals could be a good idea as I'm leaning towards some that are tall & narrow and that approach does seem to let more light in as well as giving a wider field of view - this is an interesting link: https://www.new-learn.info/packages/tareb/dynamic/docs/splayed_reveals.html

So what's the best way to do splayed reveals with ICF? - chopping corners off the blocks is obviously going to result in a nasty mess when pouring, so it looks like oversizing the apertures then building in some angled sections - but what would be acceptable to BC from the thermal point of view? Thanks!

I left ours at 50 mil plus the render 

70 over all

40 or 50 mil looks fine if you are cladding also 

 

Splayed reveals look great and let more light in 

[Russell griffiths]

If you haven’t yet 100% decided on your icf choice or even if your going to use icf, then I think it’s something not to worry about yet, these things are all minor details you will sort out, but no point doing it now if you suddenly decide to change manufactures. 

 

All blocks are different and reveals will all be made up differently depending on manufacturers. 

[willbish]

1 hour ago, Reiver said:

1) How far in/out should the window sit in the aperture? Logic tells me that the line of the glass should be over the junction of the outer (thick) insulation and the concrete pour, but is that right?

2) It looks like splayed reveals could be a good idea as I'm leaning towards some that are tall & narrow and that approach does seem to let more light in as well as giving a wider field of view -

 

I will be positioning my windows 60mm in from outside face of ICF plus thickness of render using a ply box to fix through into the concrete core. In hindsight I think it would have been preferable to use a plastic board like stokboard instead of ply

 

Splayed reveals are possible with ICF, Ive got some EPS mouldings on order which will be foamed in and rendered over. 

 

 

[Temp]

Perhaps check with the window company if you have selected on already.. Some only have a limited range of sill projection mouldings. The drip groove on the underside needs to be far enough out. 

[Reiver]

2 hours ago, Mr Punter said:

1) Normally line the glass up to the centre of the insulation.

 

2) How to do this depends on the ICF and the external finish.

Thanks for the info - given that the 2 ICF options I'm looking at both have around 200mm external insulation that's quite a bit further forward than I'd imagined, but at least it will mean the bottom of the frame will be on fairly flat EPS. Finish wise it could either be render (quicker) or stone faced (if the planners demand), the latter would demand some reasonably wide external reveals as well as the internal ones. Lots of balls in the air at the mo., just need to try and collect as much info. as possible and wang it into the spreadsheet so I can make the right decision when the time comes - can't afford to get caught out on this one!

Edited June 18, 2020 by Reiver

[Reiver]

2 hours ago, Russell griffiths said:

If you haven’t yet 100% decided on your icf choice or even if your going to use icf, then I think it’s something not to worry about yet, these things are all minor details you will sort out, but no point doing it now if you suddenly decide to change manufactures. 

 

All blocks are different and reveals will all be made up differently depending on manufacturers. 

It's still a toss-up between Isotex and Izodom 2K and I won't be making a final decision until I've got the costings done for all the various options. The purpose of asking about the reveals was to try and put some numbers on them.

[Reiver]

1 hour ago, willbish said:

 

I will be positioning my windows 60mm in from outside face of ICF plus thickness of render using a ply box to fix through into the concrete core. In hindsight I think it would have been preferable to use a plastic board like stokboard instead of ply

 

Splayed reveals are possible with ICF, Ive got some EPS mouldings on order which will be foamed in and rendered over. 

 

 

Thanks for the heads up on Stokboard, I've been looking for a plastic based board for a while.

[Reiver]

24 minutes ago, Temp said:

Perhaps check with the window company if you have selected on already.. Some only have a limited range of sill projection mouldings. The drip groove on the underside needs to be far enough out. 

That's a good point - if I end up having to stone face then it could be 100mm insulation + minimum 200mm stone. However in that situation I'd likely need to use the slate window ledges that are common round these parts, so the sill projection wouldn't need to be too big.

[Reiver]

So I sketched up what might be needed to give a decent splay and it's a fair thickness of material, between 100 and 150mm depending on the angle and the exact position of the window in the aperture, the larger thicknesses look better but eat up more aperture obviously. This is going to make fixing direct into a solid part of the ICF somewhat difficult, so whatever "packing" material is used either side of the frame to make the splays will have to be strong enough to support them, and I guess will need to have suitable insulating properties. Would the lightweight (0.11 W/mK) AAC blocks do I wonder?? or wood? HD polyurethane foam (like tooling board) would be another option and strong enough to take fixings, but is fearfully expensive.