Cold bridging around windows

selfbuildsoon

Hi, had somebody out that mentioned a steel girder holding up a cavity wall for double doors is a massive cold bridge. He said we could use aerogel and wrap it around the girder as the windows have been measured and this would help? Just wondering has anyone any other solutions?
Also, all our other windows have been built in the old way with no stepped lintels and there is no insulation between the lintels at the head of the windows(putting in bead insulation). Would it be worthwhile to put this aerogel there too or has anyone any other ideas????

BryanF

selfbuildsoon wrote: »

Hi, had somebody out that mentioned a steel girder holding up a cavity wall for double doors is a massive cold bridge. He said we could use aerogel and wrap it around the girder as the windows have been measured and this would help? Just wondering has anyone any other solutions?
Also, all our other windows have been built in the old way with no stepped lintels and there is no insulation between the lintels at the head of the windows(putting in bead insulation). Would it be worthwhile to put this aerogel there too or has anyone any other ideas????

Ask your engineer to use two structural supports - one for each block leaf or use quinlite or glassblock above the steel - re aerogel its a great product especially to remedially help solve cold bridges.

selfbuildsoon

Thanks Bryan.
Walls fully built so can't go adding in quinnlites or glassblock.
Will go with the aerogel so, but would you recommend putting this on all the heads of the windows or just the ones with steel girders?

BryanF

selfbuildsoon wrote: »

Thanks Bryan.
Walls fully built so can't go adding in quinnlites or glassblock.
Will go with the aerogel so, but would you recommend putting this on all the heads of the windows or just the ones with steel girders?

it really depends on the standard of build your aiming for and your budget. But yes, i'd probably use it and do carefully consider your air-tightness also. I'm like a broken record, but your architect should have prepared these details long before you got to this stage..

gman2k

Where have you sourced Aerogel, and what is the cost like?
PM if necessary re charter

builder1234321

Would two girders not have been used? one for each block leaf allowing insulation between them?

Or is the standard to use one wide girder spanning the two leafs and cavity?

sinnerboy

builder1234321 wrote: »

Would two girders not have been used? one for each block leaf allowing insulation between them?

Should have been

builder1234321 wrote: »

Or is the standard to use one wide girder spanning the two leafs and cavity?

Not for many many years (since the '73 oil crisis )

esox28

Not for many many years (since the '73 oil crisis )

love it...

is the poster talking about RSJ's or the steel light lintels with the insulation in the middle?

selfbuildsoon

Hey, yes two separate steel girders were used!

fclauson

thats what I have - two totally separate supports and hence will fill the gap with bead - the junction then has a very simillar U to that of the block wall (better in actual fact as the beam is I I there is more space in the middle gap to get more insulaiton in)

THE DON FANUCCI

fclauson wrote: »

thats what I have - two totally separate supports and hence will fill the gap with bead - the junction then has a very simillar U to that of the block wall (better in actual fact as the beam is I I there is more space in the middle gap to get more insulaiton in)

if you used two steel rsj girders, one on each leaf. (sounds very solid job by the way) how did you plaster these then? did you lay a block into the web of the beam? sorry if its a stupid question.

fclauson

see

https://www.facebook.com/Passive.House.Wexford/photos/pb.154344008104045.-2207520000.1453720961./165904340281345/?type=3&theater

fatty pang

fclauson wrote: »

see

https://www.facebook.com/Passive.House.Wexford/photos/pb.154344008104045.-2207520000.1453720961./165904340281345/?type=3&theater

Rather pretty and I daresay possibly orgasmic when modelled in THERM.
I’m curious about the fixing used to secure the plywood cavity closers to the blockwork (which in turn support the live loads transferred from the windows and doors)? In the absence of detailed local guidance it would be reasonable to refer to BS 8213-4: 2016 ‘Windows and doors. Code of practice for the survey and installation of windows and external doorsets’. Section 9.2 Methods of fixing, notes - ‘Fixings should be sized to securely penetrate at least 40 mm for windows and 50 mm for doors into brick, block, concrete or masonry, or 25 mm into timber framing unless equivalent demonstrable provision can be made by other means.’
With the block on edge there is a 100mm exposed face to accept the fixing. I’m not aware of any fixing into masonry that has a recommended minimum edge distance of <50mm – which will, ipso facto, occur in this instance.

Given the general enthusiasm for such cavity constructions (sans closer block) perhaps one of the engineers might care to comment on the robustness of such fixing details.... in principle.