Cavity Closer!

Rushy Fields

Hi, I am just about to commence my cavity wall construction for my self build. Can anyone PM me a detail of closing a cavity around windows and other openings, showing the apropriate insluation thicknesses? (100 internal blockwork 150mm cavity and 100mm external blockwork)

beyondpassive

Shouldn't you be looking for the thermally broken raft to internal wall detail first? Why have you not got construction drawings and details done first.

iceax

i would like to know as well... i'm going with a 150mm cavity full fill with closers R from xtraterm as well.
my issue is the use of DPC at heads with full fill insulation
dpc left and right of window with flanged fit how does this all gel together.
Also another issue im not sure about is the sill type to buy due to cavity been 150mm can't seem to find a concrete one to sit out the outer leaf.

gears

Should all cills sit not on the outer leaf???
If you're worried about balancing the cill on the outer leaf a simple steel bracket attached to the inside (with in the cavity) of the outer leaf will help support it.
Also many of the new off the shelf cavity closers have a build in DPC so there should be no worries there.

sydthebeat

all cills now sit on the outer leaf, or should any way.

most manufacturers do a cill like this. They have always done so for Timber Frame houses anyway.

esox28

op what insulation are you using in the 150mm cavity.

I am using a full fill cavity board which runs out to end of cavity's and it is then cut flush, an air tight membrane is then applied and skim coated to window edge.

Rushy Fields

I am pumping my 150mm cavity so i need to seal/close around openings but not sure how to do this the best way.

beyondpassive

You really do need to think out the closer detail on paper, here's us mocking up the detail with the builder on site for a 250 cavity. with the 2011 regs you really do need 1:5 scale construction details to coordinate the input of blockies, window installers, etc. the window installation becomes a bit tricky with large glazed screens and sliders. Its impossible to comment on details if people are building off planning drawings, at least scribble something out on the back of a chip bag.

window installation mock up.jpg

Rushy Fields

beyondpassive wrote: »

You really do need to think out the closer detail on paper, here's us mocking up the detail with the builder on site for a 250 cavity. with the 2011 regs you really do need 1:5 scale construction details to coordinate the input of blockies, window installers, etc. the window installation becomes a bit tricky with large glazed screens and sliders. Its impossible to comment on details if people are building off planning drawings, at least scribble something out on the back of a chip bag.

Thanks Beyondpassive your information and advice is very welcomed. Im afraid my raft is poured at this stage so i will not be able to do much with the bridging at that level and the blocklayer is staring next week weather permitting so i need to have decided on how to close the cavity.

beyondpassive

nealger wrote: »

Im afraid my raft is poured at this stage so i will not be able to do much with the bridging at that level and the blocklayer is staring next week weather permitting so i need to have decided on how to close the cavity.

Thats no problem, get him to build a starter row of AAC block on the warm leaf and internal partitions (loading to checked by engineer of course.)

thermals footing.jpg

esox28

one option we concidered using to close a cavity was 150mm floor PIR 'high density' insulation cut to size to fit inbetween internal block and external block cavity with the use of a dpc running down the cavity side of the external leaf as normal, you will have a dpc cavity tray between the two window lintles which will close off the top opening you can then wedge the underneath off the cavity tray between lintles with more insulation.

r you using a thermal lining board on internal block work?

one of the mistakes I made was not to leave the internal reveal block back the wigth of my cosy board, allowing the cosy board to return to window around the reveal. got it sorted anyway only using a 38mm board so wont be noticed:D

Rushy Fields

esox28 wrote: »

one option we concidered using to close a cavity was 150mm floor PIR 'high density' insulation cut to size to fit inbetween internal block and external block cavity with the use of a dpc running down the cavity side of the external leaf as normal, you will have a dpc cavity tray between the two window lintles which will close off the top opening you can then wedge the underneath off the cavity tray between lintles with more insulation.

r you using a thermal lining board on internal block work?

one of the mistakes I made was not to leave the internal reveal block back the wigth of my cosy board, allowing the cosy board to return to window around the reveal. got it sorted anyway only using a 38mm board so wont be noticed:D

Thanks esox28. I have used your idea. I did not leave the internal block back like you suggested, i finished both leafs flush with each other. Hopefuly i will be able to do what you did and use a thin piece of cosy board around the window reveal.

fclauson

nealger wrote: »

Thanks esox28. I have used your idea. I did not leave the internal block back like you suggested, i finished both leafs flush with each other. Hopefuly i will be able to do what you did and use a thin piece of cosy board around the window reveal.

You could (subject to all the normal engineering checks etc) con saw the inside leaves so as to open them up a bit e.g. cut 1.5 or 2inches off each side so that the ope on the inner leaf is wider than that on the outer

The head of the ope will be harder - depending upon your lintle design/configuration