What's wrong with my Extension?

[Lift span]

Hello,

 

I'm self building an extension and I'd like help!

 

First question:

How do a get a level threshold and avoid thermal bridging with triple track sliding doors on a block and beam floor with a steel sway frame?

 

A manufacturer has sent me this:

 

 

 

 

But, none of those details match my own.

I have Building Regs Approval (with Engineers calcs done) to build this:

 

 

 

 

 

 

I've started "building" it in Sketchup:

 

 

 

 

 

 

 

 

 

[Lift span]

I've looked at previous threads and the answer seems to be use Compacfoam.  

 

However, I'm not building a Passive House and I'm looking at alternatives,

 

The steel sway frame is shown below:

 

 

 

I've shown the block and beam almost spanning the cavity.  Then I thought of using thermalite coarsing blocks along the floor to get the correct level. Then adding timber on the vertical reveals fixed to the steel as a cavity closer (with vertical DPC).

 

Would that work?

 

[Temp]

How is it different? Looks like you are building an insulated cavity wall? No? 

[Lift span]

Thanks for the reply

That bit of compactfoam looks redundant to me. If I just fill the cavity with concrete, how do I stop/avoid thermal bridging?

[Lift span]

Yes, it's a cavity wall, to be filled with lean mix. Here is another view with the external wall removed (it's on sloping ground hence the design).

 

[Temp]

I think the compact foam is their attempt to stop thermal bridging.

 

Ideally you would extend the insulation you are putting on the B&B under the track but I suspect it needs more support. Ask the company if you can used a wider and thicker foam?

 

 

 

 

 

[Temp]

Perhaps someone makes a foam filled aluminium extrusion you could put under the track to support it and provide thermal isolation?

 

 

 

 

 

[Tom]

or a length of this stuff: https://www.armatherm.co.uk/products/frr-structural-thermal-break-material/

[Temp]

16 minutes ago, Tom said:

or a length of this stuff: https://www.armatherm.co.uk/products/frr-structural-thermal-break-material/

 

That almost looks too strong 🙂 I think wall blocks are 2.4N/mm^2 to 40N/mm^2 where as that 310 N/mm^2. Perhaps they measure it differently.

 

I would ask the door supplier what they recommend for the location marked with an arrow below. Does it have to be block work or can it be some sort of insulation and what strength? My guess is they will say blockwork.

 

 

 

 

 

 

 

 

[Temp]

Actually my drawing is missing the perimeter insulation that would be between screed and track.

[Temp]

[Lift span]

Thanks Temp. They want a concrete fill in the cavity because I think they fix into that. I'm thinking all insulation is redundant in those pictures apart from that perimeter insulation and the insulation below the screed (aluminium track).

[Makeitstop]

Could you not use thermoblock?

 

That has huge load bearing capacity and is an insulator in itself.

[Simplysimon]

+1 for marmox

[Russell griffiths]

Kingspan 500kpa xps. 

[Lift span]

Will the Kingspan 500 take a screw fixing?

 

[Russell griffiths]

22 minutes ago, Lift span said:

Will the Kingspan 500 take a screw fixing?

 

No, what are you screwing into it, your doors probably won’t have any downwards fixings. 

[Lift span]

Thanks for the reply Russell.

 

Here is a video from one manufacturer (same as in the detail pictures above). In the video they show fixing in the bottom:

 

 

[Lift span]

14 hours ago, Makeitstop said:

Could you not use thermoblock?

 

That has huge load bearing capacity and is an insulator in itself.

Looks like a great product thanks.

 

I've had a search but I can't see if that can be screwed into?

[Lift span]

Also, what about the side jambs?

 

In the video they just return the blockwork to close the cavity whilst in the detail below they use compacfoam:

 

 

I have a vertical steel so I was thinking of just using a 50x200 timber fixed to the steel, with DPC against the outer blockwork.  I asked the manufacturer if they would fix into timber and they said yes.

 

Any thoughts?

 

 

 

[Lift span]

Apparently, timber in the cavity is a no go so the answer is to use the structural foam instead. I'm thinking I should still have 4x2 timber on the face of the steel as shown below. Anyone done this?

 

 

 

 

 

Same for the header:

 

 

Edited June 28, 2022 by Lift span
spelling.

[Lift span]

Header:

 

[JohnMo]

Outer course of blocks/bricks replace with thermolite blocks, keep the 20mm compacfoam or just replace with PIR, not sure it's there for any structural reason at the threshold.  Or replace the compacfoam/cast concrete details with a full depth compacfoam and thermolite outer skin.

[Lift span]

38 minutes ago, JohnMo said:

Outer course of blocks/bricks replace with thermolite blocks, keep the 20mm compacfoam or just replace with PIR, not sure it's there for any structural reason at the threshold.  Or replace the compacfoam/cast concrete details with a full depth compacfoam and thermolite outer skin.

 

I hadn't thought about doing the outer in thermolite. I'm doing a sand and cement render on the outside and assumed the lightweight blocks wouldn't work but it seems you can! Yes, so certainly above DPC but I may well do below that thanks.

[Pocster]

Sorry , mis understood the title …