Insulating cavity between 2 steels

[Thinking_wtf]

Hi lads. I’m about to box in these steel but want some advice if poss about trying to prevent cold air transfer from the cavity wall down through the plasterboard below the steel. The cavity wall above the steel runs up to the loft and let’s a lot of cold in. I can’t afdord to do cavity wall insulation at the moment but hope to in the future. Could I pack some kingspan in there or fill it with foam? Any issues with damp or similar? Cheers.

 

[KenGMac]

Thinking_wtf, good evening.

OK If I have it correct, the "cold air" [from the far frozen upper reaches of the loft] is coming down a cavity, is the cavity at any point an external wall?

Does the cold air come down between the two RSJs?

Ken

 

[Thinking_wtf]

Hi Ken, thanks for the reply. Yes you have it exactly correct. The cavity is an external wall above the RSJs as they support the external wall next to a flat roof extension. The cold air comes down the wall from the loft and between the RSJs

 

[KenGMac]

Thinking_wtf good evening again.

OK a few questions and possible pointers?

Is there a cavity tray fitted? just above where the flat roof flashing enters the external wall?
You may be able to see the tray if you shine a strong light up the cavity, between the steel beams?
Or?
Are there small plastic inserts fitted to the vertical brick joints above where the flat roof flashing is tucked into the external wall?

Hopefully there will be a cavity tray, it is there to divert any rain penetrating the outer leaf of the brick and not allow any rain water [or condensation] from running down the inner surface of the outer leaf of brick to enter the property at the two steel beams.

Are you getting any water dripping from between the two steel beams at present?

OK [Again]

As for stopping the draught [even if there is a cavity tray fitted, the cold air will get around the ends of the tray] my preference would be simply stuffing the cavity with glass wool.
This material will tend to fill all voids and is pliable enough to do so, I would try to get about 300.mm above the steel so as to keep the steel from getting cold and eliminating the possibility of condensation occurring on the steel, the resultant drips will mark the finishes below the steel beams.

Ken