ICF Window Detailing

[Jenki]

Following on from my Foundation post,  

I want to get the detailing correct on the windows, this is spurred on further by reading this post 

 

 

My build will be with PolySteel ICF, 50mm EWI, Board on Board vertical cladding.  UPVC windows.   I'm thinking of using a stub sill on the UPVC window and then an Aluminium over sill.  

 Using the sketch by @Babak in the above post, I have come up with the following

 

Questions: 

1: I'm thinking I need to add a packer (compact foam?) under the stub sill to allow for the over sill to be sealed - is this correct?

2: I'm thinking of adding 20mm EWI on the reveal to form a cheek, so the window can be sealed to this?

3: DPM, this need to be under the sill, over the outer wall and sealed, also out past the side of the reveals with an upstand.  This detail would be very difficulty with Std DPM, so was thinking of using strips of peel and stick EPDM?   or would Triton Liquid Membrane be better?

 

To finish the reveals I'm looking at possibly using Black Soffit board as this will give a neat easy to seal finish against the frame.

  

 

 

[Jenki]

I can't believe my detailing is perfect, so maybe my post needs a little bump as it may have been lost in the other forum activity.😬

There are a few ICF builders and I would appreciate thier hard earned knowledge.  If by some fluke of nature it is perfect a little like 💙 from 1 or 2 of you would put my ever racing mind  at ease, until the next question arrises, which to be fair there's loads rattling around. Thanks 

[Mulberry View]

I wish I could help you with this, we're not at this stage yet.

 

I hate to see topics without replies. It's a little quiet in here though!

 

Free bump anyway, in the hope someone can offer some words of wisdom.

[Jenki]

21 hours ago, Mulberry View said:

I wish I could help you with this, we're not at this stage yet 

Me neither. I'm not out of the ground, but I want the details sorted now. So the day to day issues don't get in the way of the details and missed 

[Nickfromwales]

On 22/01/2023 at 08:26, Jenki said:

I can't believe my detailing is perfect, so maybe my post needs a little bump as it may have been lost in the other forum activity.😬

It's looking quite good to me atm! May be the reason this ship has been left drifting out to sea, lol.

The peel & stick is far better to use to form the 'cup' for the cill detailing imho, so yes, run with that. I have been detailing this very thing with 3 current client builds, and the consensus is to mesh and render the reveals beforehand as a belt and 2 braces approach. The render systems, as I learned recently, are just about the only thing the BBA state will adhere long-term to EPS in ICF systems and stay adhered, same basecoat which then goes externally for the rain-screen / render system.

It's pointless adding things which stick or goop that needs to bond, unless the substrate will allow a robust purchase that will last the lifetime of the build, so yes, you're absolutely A1 in getting this planned ahead, meticulously.

 

Nudura have issued this detail primarily to fire rate the internal reveals, a thing some overlook when blinded by the seemingly most pressing concern ( water ingress ) but they have issued me a statement last week stating that I could just install the mesh, then install the windows, and then render the reveals. This was a chosen path for getting a robust surface in which to apply foam and tape ( foam better than Compriband here as ICF doesn't really need deflection mitigation like a TF would ), but certainly if you could render out first, then this would give you a great surface for the peel and stick to adhere to, plus give a continuous impervious surface to the flat / bottom ( and lower edge of the sides too ) opening of the reveal.

 

The more I see of this and the further I get involved with detailing this on behalf of folk, the more I cringe, considering what I've seen, done by others, to date.

 

Keep plugging away, as this is one area where the devil is very much in the detail.

[Jenki]

3 minutes ago, Nickfromwales said:

It's looking quite good to me atm! May be the reason this ship has been left drifting out to sea, lol.

The peel & stick is far better to use to form the 'cup' for the cill detailing imho, so yes, run with that. I have been detailing this very thing with 3 current client builds, and the consensus is to mesh and render the reveals beforehand as a belt and 2 braces approach. The render systems, as I learned recently, are just about the only thing the BBA state will adhere long-term to EPS in ICF systems and stay adhered, same basecoat which then goes externally for the rain-screen / render system.

It's pointless adding things which stick or goop that needs to bond, unless the substrate will allow a robust purchase that will last the lifetime of the build, so yes, you're absolutely A1 in getting this planned ahead, meticulously.

 

Nudura have issued this detail primarily to fire rate the internal reveals, a thing some overlook when blinded by the seemingly most pressing concern ( water ingress ) but they have issued me a statement last week stating that I could just install the mesh, then install the windows, and then render the reveals. This was a chosen path for getting a robust surface in which to apply foam and tape ( foam better than Compriband here as ICF doesn't really need deflection mitigation like a TF would ), but certainly if you could render out first, then this would give you a great surface for the peel and stick to adhere to, plus give a continuous impervious surface to the flat / bottom ( and lower edge of the sides too ) opening of the reveal.

 

The more I see of this and the further I get involved with detailing this on behalf of folk, the more I cringe, considering what I've seen, done by others, to date.

 

Keep plugging away, as this is one area where the devil is very much in the detail.

Thanks for the input @Nickfromwales, only issue is 'no render'  as its being timber clad.  I could peel and stick the whole reveal, but this wont improve fire rating.  I could add cement board and then clad?

 

 

[Nickfromwales]

2 hours ago, Jenki said:

Thanks for the input @Nickfromwales, only issue is 'no render'  as its being timber clad.  I could peel and stick the whole reveal, but this wont improve fire rating.  I could add cement board and then clad?

 

 

Matters not one jot what you’re doing after, but this is the only way I will detail these junctions from hereon in. The render is just about the only thing that will stick, and STAY stuck. No good being great on the day, then gives up over the next couple of years when it’s waaaaaay too late to do anything to quick-fix this. 

Check with BCO and read up on manufacturers recommendation for these reveals, they should provide guidance. BCO will probably know the square root of fcuk all here, and could cause undue stress / work so take that info and choose what you do with it. 
FR should be a concern, as if an open flame gets to the EPS, it’s “goodbye house” at a rapid rate of knots. 

Not often discussed. 

[Jenki]

7 minutes ago, Nickfromwales said:

Matters not one jot what you’re doing after, but this is the only way I will detail these junctions from hereon in. The tender is just about the only thing that will stick, and STAY stuck. No good being great on the day, then gives up over the next couple of years when it’s waaaaaay too late to do anything to quick-fix this

so, maybe a scratch coat on the reveal before window install, then I know its stuck and seal from here. more to think about.

Does the EPS need priming before base coat? if so any recommendations for a product

Edited January 24, 2023 by Jenki
more info

[Dave Jones]

surely you need an extended cill  which physically extends the bottom of the window frame outside the structural envelope of the building then seal it underneath and the sides ?

 

illbrook do a very good complete window sealing system.

Edited January 24, 2023 by Dave Jones

[Nickfromwales]

1 hour ago, Jenki said:

so, maybe a scratch coat on the reveal before window install, then I know its stuck and seal from here. more to think about.

Does the EPS need priming before base coat? if so any recommendations for a product

Not sure is the honest answer. Learning and adapting at this very moment!!

Ask tech support at Drytek and see what they recommend, but AFAIC you just apply the mesh and render and it sticks like 💩 to a blanket.

@nod who else does these render systems ( with BBA to go onto ICF? )

@Russell griffiths what did you use, Bruce?

[Russell griffiths]

Couple of points, you drawing needs enlarging a bit so the details show a bit more. 

The extended cill needs an upstand so it tucks up and under  the upvc cill. 

 

Have you considered a piece of slate as the extended cill, I think it would fit in with your location. 

Then the upvc cill needs to have a very minimal down turn so it sits almost on top of the slate. 

 

Regarding render, pick a manufacturer and stick to there recommendation regarding preparation. 

All my stuff came from the the EWI store. 

Sticks like the proverbial shit to a blanket. 

[Nickfromwales]

2 minutes ago, Russell griffiths said:

Couple of points, you drawing needs enlarging a bit so the details show a bit more. 

Put your glasses on   

[Russell griffiths]

Buy yourself an eps surform sander thing, it’s like a cheeese grater with a handle. 

Make your openings 30mm bigger than the window or make your windows 30mm smaller 🤪

this will allow for 5-7mm of render on both sides, then adequate room for the nozzle of your illbruck foam gun. 

 

Use the sander to put a slight slope on your blocks in the cill area. 

Then render cill area and reveals and head. 

Two coats of a waterproof coating, then fit the windows. 

 

If you can bend and stretch the peel n stick membrane around the cill area with any sort of good result, I will nominate you for a noble peace prize. 

[Russell griffiths]

16 minutes ago, Nickfromwales said:

Put your glasses on   

Who said that. 

[Nickfromwales]

19 minutes ago, Russell griffiths said:

If you can bend and stretch the peel n stick membrane around the cill area with any sort of good result, I will nominate you for a noble peace prize. 

I've recommended doing this in sections, same way an EDPM roofer would detail a roof membrane.

 

8 minutes ago, Russell griffiths said:

Who said that. 

You don't have to go to Specsavers Bruce, they'll come to you  

[ChrisJ]

On 24/01/2023 at 11:10, Russell griffiths said:

 

 

If you can bend and stretch the peel n stick membrane around the cill area with any sort of good result, I will nominate you for a noble peace prize. 

 

I’ll have to show you the butterfly for the cill corners - can I take a Guinness instead of the Nobel prize 

[Jenki]

4 hours ago, ChrisJ said:

 

I’ll have to show you the butterfly for the cill corner

You'll have to expand on this. Is it similar to the folds when doing rubber roofing?

[ChrisJ]

On 25/01/2023 at 22:21, Jenki said:

You'll have to expand on this. Is it similar to the folds when doing rubber roofing?

Be about 10 days and I’ll be on a project with some peel & stick and send a pic 

 

remind me tho

[ChrisJ]

[ChrisJ]

[ChrisJ]

[ChrisJ]

[ChrisJ]

On 25/01/2023 at 22:21, Jenki said:

You'll have to expand on this. Is it similar to the folds when doing rubber roofing?

Took me a while to get one ready but that is the butterfly to seal the pinhole corner in the window flashing from cuts and folds - you should also caulk (not silicone) the seams 

Edited April 25, 2023 by ChrisJ

[FM2015]

Edpm tray with upstand stuck to cill

 

Cill to extend wider than opening (horns)

 

"Check" reveal for sides and head former by outer layer of ICF form or custom formed closer

 

Silicone outside of frame to reveal

 

Foam and airtight tape for inside junction.

 

One aspect frequently overlooked is maintenance. Ask yourself this question: does my method of window fitting and sealing result in the need of a renderer if I need to replace a window?  Or mason or carpenter for clad walls?

 

The above method just needs a window fitter.  A physical dog leg in the form of a structural check reveal will outlast all tapes.

 

The above method is also the most similar to every other "conventional" build system.  Therefore the initial fitting cost should be less expensive.

 

Just my tuppeneth

 

 

[Jenki]

7 hours ago, FM2015 said:

One aspect frequently overlooked is maintenance. Ask yourself this question: does my method of window fitting and sealing result in the need of a renderer if I need to replace a window?  Or mason or carpenter for clad walls?

@FM2015, so I think your saying, if you fit EWI to create a check reveal and seal this corner, if the window needs replacing, you can cut the silicon and remove / replace the window to the inside? Do you use trims internally? Other wise the plasterboard would need removing? Just not fully understanding🙈.

I plan to use EWI and create this joggle.👍