UFH in Foundation Slab Expansion Joints

[AliG]

We just received drawings from MBC showing that they will cut expansion joints in the passive raft foundation.

 

This then had me asking the question what happens to the UFH pipes when they cross the expansion joints?

 

Waiting to hear back from the foundation engineer, but it doesn't seem like it would be an unusual issue, so has anyone come across this before?

[Russell griffiths]

I’ve never Seen an expansion joint in a slab, not unless it is a funny shape with a skinny bit that will definitely crack where it joins the fat bit. Or if it was many hundreds of metres square. 

 

My last place had a ground floor slab of 340m without any expansion joints. 

[IanR]

24 minutes ago, AliG said:

We just received drawings from MBC showing thatchy will cut expansion joints in the passive raft foundation.

 

This then had me asking the question what happens to the UFH pipes when they cross the expansion joints?

 

Waiting to hear back from the foundation engineer, but it doesn't seem like it would be an unusual issue, so has anyone come across this before?

 

What's leading to the need for expansion joints. On my 26m x 19m insulated raft, expansion joints were discussed, but only by the ground workers that I was asking to quote. In the end I went with a group used to doing warehouses who were happy going 4 times the size without expansion joints. 

Edited February 9, 2022 by IanR

[AliG]

Maybe it is just the shape of the slab. Blue dashes are the expansion joints.

[George]

Shouldn't need any expansion joints at all. May be mislabelled contraction/control joints, but I'd be looking to eliminate/minimise those with the concrete design.

 

If the pipes are going into the structural slab then will probably need to co-ordinate the pipework layout and the actual construction joints if it can't be poured in one go.

 

If a control joint is still required, you'll likely need some sort of former, as the usual method of a Stihl saw is out. 

[Russell griffiths]

If they did put them in, would this mess up your floor finish, as you would need to carry the joint up through the finished floor. 

[Nickfromwales]

If this is a constructional concrete slab with re-bar / ring beams and intersections, then I’ve seen far more complex slabs down without any of that. 
Is this to take their ( MBC’s ) passive or regular TF? Just wondering what the required flow temp will be. If low, as in very low, then I strongly doubt these are required.

[AliG]

It’s the regular TF 0.14 U-value.

 

Won’t be quite passive but close to it. Can’t imagine a flow temp much above 30C.

 

When I looked at the solar gain calf’s the heating would theoretically hardly ever need to be turned on.

 

Still not heard back on their solution. We can’t be the only people with expansion joints and UFH in the slab. Online I saw pics of formers.

 

Wouldn’t really impact the floor finish as it is basically at doorways except the bedroom door.

 

I might ask if they are really necessary.