Having difficulty visualising the position of the steels in the wall. Have you got a cross section sketch that you could post. Presumably architect /SE been involved what have they got to say.

Hi guys,

I have attached the plans below. I have designed the house myself and the timber frame company did the actual frame design so no architect. The steels are in the stud walls as you can see from the drawings. Any thoughts would be helpful!

You maybe want to upload higher-resolution images to someplace and link to them. It's not clear where the steels are on the images you're limited to on this site.

A sectional detail around the stanchions and frame would be useful as I cannot make out with sufficient clarity. Presumably it is a 2 storey house so the steels supporting upper floor will need fire proofing. If you have them painted with intumescent paint it will be easier than fireproofing by boxing in. It is a mistake I made and it was far more effort to box in it is easier to paint.

Ours was built with an A frame steel within the insulated (blown paper) walls/roof of the house. I made a great song and dance about the steels needing a thermal break where the verticals poked down through the walls between the brickwork/blockwork apron air brick ventilated cavity and onto the concrete raft (non insulated).

Both architect and builder not interested, stating that it was not necessary. My view was that the let's say -12C base of steel going straight up into warm wall would be a condensatory disaster. I lost out on this one.

Suffice to say that upon later inspections in cold/humid conditions the steel both internally and externally remains bone dry. The additional heat loss no doubt is negligable. No cold spots or mould growth.

I'm sorry i never got back to anyone on here, who knew building your own house would be so time consuming!!

Thanks for all the thoughts. It's reassuring to see you had the same concerns as me dickster but no issues.

The house is up but not insulated yet. There are a number of steels that are flush with the external face of the osb wall. I was thinking about just using Rockwool, wood fibre or blown insulation 140mm in the walls and then wrapping the whole house in Pavatex 100mm to break these steels from the outside and then to not add much insulation on the inside of those steels (so as to further reduce risk of condensation. I was also thinking of using 10mm of Aerogel to the inside face of the steels where the windows are going to break them from the Glazing, so any thoughts on this would be great. Rockwool is far more on budget for us than wood fibre in the walls so any thoughts on this would be great. The roof is a warm deck flat roof with 275mm of Hardrock rockwool on it.

Lots of pics in full size here
https://www.dropbox.com/sh/zxx5l6qcjv85lnn/AABbGIsjwYQnyi4J5VFdOaQEa?dl=0

Any thoughts would be appreciated, or any suggestions for a good insulation supplier who can give unbiased advice on combining pavatex with rockwool in this way.

Posted By: nickbartleetI'm sorry i never got back to anyone on here, who knew building your own house would be so time consuming!!

Thanks for all the thoughts. It's reassuring to see you had the same concerns as me dickster but no issues.

The house is up but not insulated yet. There are a number of steels that are flush with the external face of the osb wall. I was thinking about just using Rockwool, wood fibre or blown insulation 140mm in the walls and then wrapping the whole house in Pavatex 100mm to break these steels from the outside and then to not add much insulation on the inside of those steels (so as to further reduce risk of condensation. I was also thinking of using 10mm of Aerogel to the inside face of the steels where the windows are going to break them from the Glazing, so any thoughts on this would be great. Rockwool is far more on budget for us than wood fibre in the walls so any thoughts on this would be great. The roof is a warm deck flat roof with 275mm of Hardrock rockwool on it.

Lots of pics in full size here
https://www.dropbox.com/sh/zxx5l6qcjv85lnn/AABbGIsjwYQnyi4J5VFdOaQEa?dl=0

Any thoughts would be appreciated, or any suggestions for a good insulation supplier who can give unbiased advice on combining pavatex with rockwool in this way.

Hello Nick,

My recent experience of selecting insulation systems for my build has been that suppliers will typically have one or more systems they've designed that may either have BBA certification or is a registered LABC detail. You'll typically find that to derive most benefit these systems will utilise similar materials across the system. For example, using wood fibre throughout the wall structure. That doesn't mean to the say you can't build up your walls with different materials, like Rockwool and woodfibre.You just won't necessarily gain the full benefit of the system. For example, Rockwool is not hygroscopic. I have seen examples of people using mineral wool with Pavatex on timber framed walls.

I'm still rather bemused why designers design what are supposed to be energy efficient buildings with steels embedded in the walls creating such cold bridging. Our architect did the same with our build with one steel spanning the whole width of the house. I was lucky enough to be able to move the walls where this was a problem so the steels all sit within the insulated fabric of the house. I also had our structural engineer design a couple of cantilevered floors and roof in order to remove several bay window posts that would have been terrible cold bridges.The initial design was, like in your instance, to use an aero gel or similar around the bay posts. Now I have non structural timber posts instead.

I think your idea to have an external layer of insulation outside the frame and steels is a sensible one.