Cold Bridge Issue

creedp

We have a living room off our kitchen/dining area. Rather than have it completely open plan we wanted a stud wall to divide both rooms. This stud wall would have a doorway without a door and would have both a horizontal and vertical cut out to ensure visibility between both rooms. An RSJ was installed to support hollowcore and upstairs wall/roof. I was always concerned with this RSJ from a cold bridge perspective as one end was very close to an external wall and the end of it was above rafter level so a cold bridge problem already existed.

The builder said he would have to put in a steel support for the stud wall as otherwise it would not be ridgid enough. I didn't think much off it until he range me to say it was in place and when I saw the steel 'superstructure' it screamed cold bridge.

To explain he had bolted 3 40mm by 500mm steel plates to the subfloor and onto each of these welded 2 40mm square box iron 'standings' [sorry cant think of proper word], that's 6 box oron standings in all. 4 of these are full wall height and welded to RSJ while the last 2 are approx 1.2m high and welded horizontally to the middle 2 box irons. Sorry is very confusing description. In any case what I have is a substantial amount of steel welded to the subfloor and going full wall height and welded to an RSJ.

Should I insist that this structure be adjusted, e.g. by creating a thermal break between the subfloor and steel using quinnlite blocks. The inner leaf of external wall are built with quinnlites as are the 1st 2 courses of all the inner walls. I anticipating fierce resistance to any request to change this thing as it took most of a day to put it together. Is it a dealbreaker from a cold bridge perspective? If not critical I might have to back down with my demand to change it if things got ugly. What do you think?

All views apreciated

Thanks

L driver

Hello,
Could you use structural eps/xps underneath. Sounds like a proud builder, "well it won't fall", who does things his way?

creedp

Thanks for the reply L driver. I won't attempt to reintroduce the structural EPS to this man. I tried valiantly to go with an insulated raft and failed miserably - my fault as there is a horse for every course!

My only hope would be to use quinnlites as he is already comfortable with these. The biggest problem I have with this stud wall is that the heaviest part of it is the steel which is massively over-engineered but as you say 'it will never move!!'

I know its a cold bridge but with its limited footprint, compared to full a wall that is, is it very problematic? Will it result in condensation/mould behind the plaster board? Would wrapping the steel in insulation help in any way?I know I appear unable to deal with the problem by insisting on it being removed but my life these days is spent attepmting to make changes to work already done in order to improve airtigtness/cold bridges and I simply want to pick my battles. However, if its a major problem obviously it goes straight to the frontline!

Thanks again

dathi

hi i could be reading this the wronge way is the living room built like an extension to the main house with a hiped roof butting up to the gable or rear wall of main dwelling? if so all of the wall between house and living room is a cold bridge and needs insulated slabs or similar if you think about it the outer 100mm block goes from the out side of the house through the roof space and ends up inside your house.

creedp

dathi wrote: »

hi i could be reading this the wronge way is the living room built like an extension to the main house with a hiped roof butting up to the gable or rear wall of main dwelling? if so all of the wall between house and living room is a cold bridge and needs insulated slabs or similar if you think about it the outer 100mm block goes from the out side of the house through the roof space and ends up inside your house.

Yes it is as you describe and yes the wall from the roof of the living room down to RSJ is effectively a cold bridge to the outside gable wall. However the inner leaf of all the external walls are built with quinnlite blocks and in the case of this wall under the roof level of the living room both the inner and outer leaf are built with Quinnlite blocks which I hoped would help reduce its cold bridge effect. That was the plan anyway.

dathi

is your cavity full fill or kingspan because if you think about it the insulation will be in the wrong place once the wall goes below the roof and into your new living room the easy way to make the insulation continuous is to use insulated plasterboard on that wall and on the sides and head of the opening

creedp

dathi wrote: »

is your cavity full fill or kingspan because if you think about it the insulation will be in the wrong place once the wall goes below the roof and into your new living room the easy way to make the insulation continuous is to use insulated plasterboard on that wall and on the sides and head of the opening

I have a full fill 150mm cavity so should be better than having a cavity board. I don't like insulated drylining mainly bacause of what I've read on this site.