Warm Roof to ICF Wall Detail

[Willus]

Hi Everybody 

 

I'm wondering if anyone in the forum has already solved this problem.  We have ICF walls with a wall plate that in the architect drawings will be set level with the ICF block i.e. the top of the wall plate will be at the same height as the insulated part of the blocks either side and the trusses will be in contact with both the wall plate and the insulated blocks.  Above the trusses will be a warm roof with the insulation going past the position of the wall plate towards the eaves.  This however leaves us with the space between the top of the wall plate/ ICF blocks and the insulation laid above the trusses that we need to insulate.  We have a shallow pitch to the roof of about 15 degrees so the space is fairly tight.  

Our relationship with our architect went south some time ago, and based on the experience we have had he would not have created the right detail anyway, so we are working with our builder directly.   We have discussed a number of options from trying to notch the ICF and only pour the concrete to lower height to enable us to then angle cut it to the angle of the trusses once they go in,  retro fitting PIR into the space between the trusses with required angle cuts or using mineral wall to pack out the area.  VCL layer will obviously be internal to all of the insulation. 

Any thoughts on the best approach - what else have people done? 

 

Thanks 

 

Will

[BotusBuild]

First off, keep it simple and easy to do.

 

Cutting PIR to a required angle, or using mineral wool is the easier route.

Personally I would use PIR and Illbruck FM330 (check this, may not be right) closed cell foam to close the gaps. For belt and braces, then tape the joints with a some air tightness tape.

You'll be doing all this while the trusses are open from above and below so should have room to do it. Just a bit fiddly and time consuming, but easy!

[Redbeard]

Yes, FM330 is air-tight foam.

[Nick Laslett]

Not sure if this helps, but here is a wall plate detail from Beco Wallform:

 

https://becowallform.co.uk/technical-data/construction-details/wallplate/

 

 

[Nickfromwales]

4 hours ago, Willus said:

Hi Everybody 

 

I'm wondering if anyone in the forum has already solved this problem.  We have ICF walls with a wall plate that in the architect drawings will be set level with the ICF block i.e. the top of the wall plate will be at the same height as the insulated part of the blocks either side and the trusses will be in contact with both the wall plate and the insulated blocks.  Above the trusses will be a warm roof with the insulation going past the position of the wall plate towards the eaves.  This however leaves us with the space between the top of the wall plate/ ICF blocks and the insulation laid above the trusses that we need to insulate.  We have a shallow pitch to the roof of about 15 degrees so the space is fairly tight.  

Our relationship with our architect went south some time ago, and based on the experience we have had he would not have created the right detail anyway, so we are working with our builder directly.   We have discussed a number of options from trying to notch the ICF and only pour the concrete to lower height to enable us to then angle cut it to the angle of the trusses once they go in,  retro fitting PIR into the space between the trusses with required angle cuts or using mineral wall to pack out the area.  VCL layer will obviously be internal to all of the insulation. 

Any thoughts on the best approach - what else have people done? 

 

Thanks 

 

Will

Close the eaves externally and blow it full of cellulose? That'll get into every nook and cranny.

[Iceverge]

Have the trusses been ordered? 

 

Can you provide a cross section? 

 

 

[Willus]

Thanks for the feedback everyone - my instinct was similar to the suggestion made by @BotusBuild and to keep it simple and use the PIR with cut angle and foam and tape them.   @Iceverge we are waiting on the trusses final design at the moment but effectively there is a lower eave on the building so the heel will be directly on the wallplate and will just be the depth of the wood.