Window Jamb Insulation

[vfrdave]

I am getting close to having windows installed (its been a long journey to here), my brickies have installed dpc and then vertical insulation reveal strips to the inside of the external skin of block and returned the inside block to meet this and close the cavity.  At the head we have nothing other than internal & external head along with a filler head to partially close the cavity.  My thought is to use some more pir reveal strips to close the remainder of the cavity and some low expansion foam if necessary.  Is my thinking right?

 

Lets assume it is, I am full filling the cavity with blown beads what should I do with the area under the sloped DPC above heads (see image)?  Do I just leave this and assume/instruct/trust the insulation installers to blow beads into this section?

Thanks again in advance.

Edited February 7, 2018 by vfrdave
clarity

[PeterW]

4 minutes ago, vfrdave said:

my brickies have installed vertical reveal strips and returned the inside block to close the cavity

 

Do you mean they have fully breached the cavity with block..?? Thats a monumental cold bridge and should have a cavity closer in it instead.

 

We used these, and they perform both the DPC and insulated closure. I then taped them to the inner block with air tight tape. Graphite blown bead into the cavity following this.

 

The contractors know that they don't drill or fill directly above the window opening so no issues there. Beads will fall and compact over 8m, and a width of 2m easily so you get no cold areas.

[vfrdave]

@PeterW I have edited the above post to clarify that there is not a monumental cold bridge.

 

9 minutes ago, PeterW said:

The contractors know that they don't drill or fill directly above the window opening so no issues there. Beads will fall and compact over 8m, and a width of 2m easily so you get no cold areas.

To clarify, are you saying that they don't drill or fill directly above the window in order not to damage or disrupt the DPC and that the beads will find their way in there from the other fill points that they use?

 

Am I right with the PIR reveal strips to close off between the heads?

[Declan52]

The block being returned is the inside skin turned in towards the cavity. Depending on how wide the cavity is you will either have a block cut to 7 inch and then a brick on the next course so you end up a 25mm strip of insulation and then dpc then the out side skin. This would be for a standard 100/100/100 type build. If you cavity is wider than 100mm then you can go for a wider strip of insulation to fill the gap. It's standard build here in NI to do it this way.

I just cut strips of pir insulation and put them into the gaps below the dpc. Just takes a bit of time to wedge it up and leave no gaps.

[vfrdave]

That's what I have @Declan52 only with a 50mm reveal strip.  Are you saying you filled the whole of the gap below the stepped DPC with PIR, not convinced I would get this completely filled with a rigid insulation.

[Declan52]

Yeah I cut mine like a wedge shape then the next board on top of the dpc cut at the same angle so the dpc is sandwiched in between but slopes down so any moisture can run down and out.

It should be easier for you as you are using beads. Cut the pir and put a squirt of foam/ grap adhesive to hold it in place. How big the piece of pir is will depend on the length of dpc you have so it laps down and out the front.