Corner Window, Box Section Lintel and Insulation

rhennessy

Hi,

I am having my windows (alu-clad) installed in a few weeks one of which will be a corner window with a steel box section in the corner supporting the steel lintel. The box section will be clad with aluminium afterwards to cover the steel post. I have been to a few houses with a similar window where this part of the window that covers the box section has been very cold compared to the rest of the window and has had a lot of condensation on it. I have heard about filling the box section with expanding foam but I don't see this as doing a great job as the cold will still travel to the inside.

Any other suggestions as to what I can do here to prevent this cold bridge?

Thanks

sinnerboy

Sometimes it is possible to offset the post so that it lines up below the inner leaf and not the cavity . Then the window passes in front of the post and the post remains within the heated space .

It depends on the overall opening size and the loading imposed on the corner lintol together with a willingness of your engineer and lintol supplier putting some structural design effort in as opposed to "the usual arrangement"

rhennessy

Sounds great but unfortunately everything is in place at the moment. Has anyone encountered this before and what have folks done to remedy it?

mickdw

It is only in highly insulated houses that these type of issues are now coming to light with mould etc forming at the cold areas whereas a few years ago, no issue.

Given that you pole is in place & is at the corner of the window & not taken inboard as suggested above, you are limited to the amount of insulation that can be fitted around the pole in its enclosure I would have thought.
Im no energy expert but it couldnt be that hard to match the insulation properties of a window frame surely? How thick would a high quality insulation have to be?

sinnerboy

rhennessy wrote: »

Sounds great but unfortunately everything is in place at the moment. Has anyone encountered this before and what have folks done to remedy it?

Move the post if at all possible . Don't dismiss this because it seems like too much hassle - it's not really - this is what angle grinders and site welding kits are for . Ensure the oversite of your certifying engineer of course .

Otherwise you need to find space for insulation by forming a ply boxing around the steel post to cover over a min 25mm pir insulation wrap . Then overclad externally with aluminium sheet to match your windows . This will be hassly and will not look good .

braftery

Hi there,

Ask your window company for the detail drawing of what they recommend.

I am surprised that they did not have the discussion at the time of measure with you or your builder.

The corner window will have been measured based on where the post is now .. you are not in a position to change it without risking the window no longer fitting the opening.

It is important to make sure you know the window section, the bottom threshold detail, the cladding details and how they are all connected before you can move anything. All of this will be in a detail drawing from the window company.

soldsold

This sounds like a job best suited to aerogels insulation which is about three times better than PIR boards. With a bit of luck a 9mm or so layer of aerogel may fit on the post and still get the aluminium section to fit around it

Viking House

There is also the cold bridge where the post sits in the ground, has this been dealt with?