Draughts from lintel

[j_s]

Hi guys

 

Got an issue with one lintel that is currently accessible in a bedroom I am renovating as part of sorting the whole house. This cold windy weather has allowed me to feel draughts coming from all the little gaps that I assume are for the plasterboard adhesive etc to stick to. I've tried to foam them but they are too small. I do have Jeremy's little home made foam gun attachment but I think I need to get a lot more foam up in there. The lintels are insulated and I will be taping the lintel to the window after I sort out the foam. Can/should I drill some larger holes so I can really get some foam in there. It's really cooling the room down as no radiator or insulation above the ceiling yet due to overboarding needing to be done and I want to make sure holes are taped if any are made into the loft space by accident and the insulation will get in the way.

 

Thanks James

 

[Cpd]

Not sure I can help on your specific situation but during my renovations I had to deal with draught coming in between some timber joints, really small gaps..... so I drilled holes just big enough to get the nozzle of the foam gun in and jammmed it in and gave it a good squirt. It worked really well and I repeated as required. It made no difference to the structure as the holes are tiny and only go in about 50mm but it sealed the gaps and no more draught. 

[Ferdinand]

Can something be done with an intumescent strip?

 

eg apply a heat-expanding one (eg firedoor stuff) then play a blowtorch?

[j_s]

I ended up drilling a hole or 2 and firing some foam in. Still not taped yet but will do that tonight. 

 

I'd like to add about 12mm of pir board to the lintel (only got about 30mm to play with including plasterboard and skim). I have 25mm celotex already so will potentially rip that down to 12. Any advice as to attaching the pir to the lintel. My worry is the pir will be a bit crumbly and something like sticks like **** or CT1 or sikaflex won't hold too well to the pir board. Any ideas guys?

 

Thanks

[Declan52]

The  pir only has to stay in place long enough to let you get the plasterboard up and  when pushed in tight it will hold it.  Expanding foam would be my choice. 

[j_s]

Ok thanks declan, do you think using the Soudal low expanding flexible foam would suffice or a foam more designed for fixing boards like Dow insta stik

[PeterW]

10 minutes ago, j_s said:

Ok thanks declan, do you think using the Soudal low expanding flexible foam would suffice or a foam more designed for fixing boards like Dow insta stik

 

They are the same thing .... if you leave a low expanding foam for 5 mins - and give a quick mist of water from a garden sprayer - it will expand to about 75% of its final volume. If you then squash it onto a wall or a board it will pretty much bond instantly. Hold it with a temporary brace and it will be rock solid in an hour. 

[Onoff]

3 hours ago, j_s said:

I ended up drilling a hole or 2 and firing some foam in. Still not taped yet but will do that tonight. 

 

I'd like to add about 12mm of pir board to the lintel (only got about 30mm to play with including plasterboard and skim). I have 25mm celotex already so will potentially rip that down to 12. Any advice as to attaching the pir to the lintel. My worry is the pir will be a bit crumbly and something like sticks like **** or CT1 or sikaflex won't hold too well to the pir board. Any ideas guys?

 

Thanks

 

How about 27mm insulated pb if you've only got about 30mm? It's precisely because of minute draughts I decided to line my reveal with a vcl. 

 

I stuck the 27mm stuff to the vcl (blue dpc) with a mixture of Sikaflex EBT and foam:

 

 

 

 

 

 

No pinpoint draughts as such now other than the big cold bridge which is the 2G window!

[j_s]

Thanks guys

 

Onoff, which product did you use for the 27mm board?

 

 

[Onoff]

13 minutes ago, j_s said:

Thanks guys

 

Onoff, which product did you use for the 27mm board?

 

 

 

Gyproc Thermaline 27mm from Travis Perkins. 

[j_s]

Ok cheers, will measure the lowest point to make sure the 27mm board will fit

[j_s]

A little update

Taped the window to lintel but had trouble with the tape sticking to 1 section. Got the orcon adhesive out which solved it. I then used sikaflex on a different part of the lintel where the metal joins the inner and outer part to seal it up. I think it feels a lot better now but it has been warmer this weekend. 

 

Still more work to be done to this room but builder and joiner are in this week to overboard the ceiling and redo part of one of the stud walls with new sound insulation, 40mm conduit for aerial, satellite and cat 5 cables , 12mm ply and then plasterboard. Original ceiling will be sealed to ply with blowerproof, then overboard, any gap then foamed. I also tape above in the loft over the stud wall top plate.

 

The new insulation in other areas of the loft is already cooling the loft right down so very much paying attention to finding any tiny holes, cracks etc as I don't want any condensation up there! The roof is vented on all 4 sides as well as having breathable roof felt but obviously on much colder days and still days there is still a danger.