UFH Pipe circuits and Ground beams

[Selexus]

Hi All,

 

I'm after a bit of advice on running UFH pipe across my insulated raft foundation.

As a lot have done my plan is to embed the UFH pipes in the slab, clipped to the mesh, and run back to the centrally located Manifold.

I had planned to clip the pipes to the bottom layer of mesh, and the put the chairs and top layer in, so somewhat protecting the pipes and having at least 200mm of concrete above to safeguard against hitting a pipe if a fixing needs to be driven into the slab.

However my SE (who has been great) has decided to design an aircraft carrier and I'm now presented with several ground beams the support the raft and some of the point load areas. These create smaller pockets that i have no idea how to route the UFH pipe into as the ground beam cages create an obstruction to routing the pipe.

A section of the raft plan is below - 

 

I could clip to the top layer of mesh, but that means i have no insurance against someone driving a fixing into the slab and hitting a pipe !

Has anyone any ideas how i get around this ?

 

Thanks

S

Edited August 1 by Selexus

[BotusBuild]

I may have missed something here. I'm assuming the ground beams (the dashed bits?) will be poured at the same time as the raft - they would just be thicker than the rest of the slab, say 350 instead of 250mm deep.

If so, then just lay your pipes as you have described, although I tied ours to the top mesh, before you pour the concrete.

Edited August 1 by BotusBuild

[Selexus]

4 minutes ago, BotusBuild said:

Mat have missed something here. I'm assuming the ground beams (the dashed bits?) will be poured at the same time as the raft - they would just be thicker than the rest of the slab, say 350 instead of 250mm deep.

If so, then just lay your pipes as you have described, although I tied ours to the top mesh, before you pour the concrete.

Yeah..i see what you mean...sadly that's not how the slab is constructed.

 

 

Is a section of one of the main ground beams. 

[BotusBuild]

I'm going to step back as I can't figure out the relationship between those two diagrams. I'm finding it hard to visualise.

For others help the answers to the following may help -

1. Are the ground beams pieces of steel?

2. How many ground beams?

3. Does the slab sit on the ground beams? Or, are the ground beams embedded in the 250mm slab?

4. Is the SE aware of your requirement to put the UFH in the 250mm slab? He may design differently if he knows this.

 

Sorry I can't help further at the moment 

[jack]

16 minutes ago, BotusBuild said:

1. Are the ground beams pieces of steel?

 

The ground beam above looks like reinforced concrete, with cages having 16 mm internal longitudinals (don't know the proper term for them) and 8 mm rings (ditto).

 

That said, I can't visualise it either. Selexus, are you saying something like the cages for the ground beams sit higher than the lower level of mesh you want to tie in to, and you're therefore unable to easily lay out the UFH pipe because the tops of the cages are in the way? 

 

A couple of sections showing the relationship between the ground beams, the mesh, and the insulation would be very helpful.

 

I have reinforcement beams in my raft, but the cages for those sit below the mesh, in channels formed in the insulation. 

 

[JohnMo]

So I assume internal walls will be going in. Map out where the rooms/internal walls are. Then do circuits/loops in each, and take those loops through the doorway into room. Your loops do not go the the very edge of room, so stay either side of a wall by 150 to 200mm then you have quite a bit of leeway.

 

Sort of like this

[Nickfromwales]

Your SE has made this difficult to integrate UFH pipe anywhere other than atop the steel. Why make life harder, and just do this?

 

You can find the UFH pipes after the pour with a FLIR camera, if you REALLY need to make such penetrations into the slab afterwards, eg where the pipe doesn't already avoid such things like walls and sole plates and what-not which will be nowhere near by design.

 

PS, are you building an NCP or using a monster ICF system?? This slab with a 250mm general core already reinforced should be man enough to take most loads (load bearing walls anyways!?!). Jeez!

[saveasteading]

If i understand this design, the slab has 2 layers of mesh, but at the lines shown the slab has additional reinforcing bars (in plane) to render the slab into beams.

It seems cautious but isn't hugely expensive.

 

What do you think you might screw to the floor? All I can think of in a house is a kitchen island. Perhaps a stair? Or a particularly heavy column.

 

Anyway the  pipes can be laid through the beams before concreting, as it is simply a cage, and can be as high or low as you wish. So lower the pipes lically or divert them around any fixings area.

[Selexus]

8 hours ago, Nickfromwales said:

Your SE has made this difficult to integrate UFH pipe anywhere other than atop the steel. Why make life harder, and just do this?

 

You can find the UFH pipes after the pour with a FLIR camera, if you REALLY need to make such penetrations into the slab afterwards, eg where the pipe doesn't already avoid such things like walls and sole plates and what-not which will be nowhere near by design.

 

PS, are you building an NCP or using a monster ICF system?? This slab with a 250mm general core already reinforced should be man enough to take most loads (load bearing walls anyways!?!). Jeez!

 

Yes fair points. Due to site conditions i was looking to screw the ICF bracing down onto the slab to support the walls during pour. I'll figure something else out.

 

1 hour ago, saveasteading said:

If i understand this design, the slab has 2 layers of mesh, but at the lines shown the slab has additional reinforcing bars (in plane) to render the slab into beams.

It seems cautious but isn't hugely expensive.

 

What do you think you might screw to the floor? All I can think of in a house is a kitchen island. Perhaps a stair? Or a particularly heavy column.

 

Anyway the  pipes can be laid through the beams before concreting, as it is simply a cage, and can be as high or low as you wish. So lower the pipes lically or divert them around any fixings area.

 

Correct on the reinforcement. I think if i wanted to i could run the pipes along the bottom layer of mesh (before the cages are dropped in) and loop then under the bottom layer at the point they cross the cages, clipped to the underside of the mesh. Lower the cages in and continue the buildup.

Or just go on-top as nick has said 🤷‍♂️

[saveasteading]

Cages in first?

 

45 minutes ago, Selexus said:

screw the ICF bracing down

There is surely a proven alternative I'd hope.

Or... stick some vertical bars in your pour as anchors and cut them off later.

[JohnMo]

So daft question where is your insulation for the floor?

[Nickfromwales]

1 minute ago, JohnMo said:

So daft question where is your insulation for the floor?

 

18 hours ago, Selexus said:

I'm after a bit of advice on running UFH pipe across my insulated raft foundation.

EPS basket then? 

[JohnMo]

1 minute ago, Nickfromwales said:

 

EPS basket then? 

Still confused about all the ground beams and where they fit in with the insulation. If they are actually ground beams and insulated raft, will it be with lots of thermal bridges?

[JohnMo]

Too many snippets of information and no real drawings to what's what. It can't be hard.

[Nickfromwales]

1 minute ago, JohnMo said:

Still confused about all the ground beams and where they fit in with the insulation. If they are actually ground beams and insulated raft, will it be with lots of thermal bridges?

I’m assuming 300mm of EPS under a flat 250mm constructional slab? Eg no divots in it so no need to add an extra 100mm of EPS underslung at each intermediate location. 

[Nickfromwales]

5 minutes ago, JohnMo said:

Too many snippets of information and no real drawings to what's what. It can't be hard.

Yes. Some sectional drawings would help, but the issue is about getting UFH pipes to traverse this structure and I’d defo say on top. H-H shows more concrete cover atop, but the cover may be very minimal over the top of the pipes, but these beams can be circumnavigated by the UFH loops I’m sure. Heat will jump these gaps in a 250mm slab? 

[Selexus]

Sorry Gents, stepped away for a little trip. Back now.

 

On 02/08/2025 at 12:27, Nickfromwales said:

I’m assuming 300mm of EPS under a flat 250mm constructional slab? Eg no divots in it so no need to add an extra 100mm of EPS underslung at each intermediate location. 

 

Yes Nick, 200mm of XPS under. On top of the existing concrete slab, that we're treating as subbase. Then a flat 250mm reinforced slab.

 

This detail should provide more context it's the same section of H-H but without the reinforcement detail.

Also an edge of raft detail to bring more context

 

 

This is the GA for those that are wondering about shape and size of building.

 

 

I'm definitely leaning towards clipping to the top mesh. Giving this some more thought it makes life much more simple and I'm sure there will be very few occasions where i need to drill the slab, so....

 

Thanks

 

[saveasteading]

This design is so over the top.

 

OK the 100mm of concrete isn't suitable as your slab but it is presumably intact and strong.

 

25mm to 100mm blinding is remarkable. Is it  to provide a level surface or hide a grotty surface? But 75mm variance?

If anything it's a weakness and will have footprints in it. 

 

250mm reinforced slab on all that? It's not going anywhere.

 

How about zero to 25mm blinding, and 200mm slab?

The joint looks industrial too and could be simplified.

 

If this is a steelworks or military tank factory rather than a house then ignore my comments.

 

I apologise for being whimsical, but I've built heavy duty factories  and lorry garages with 30t hoists , slightly lighter than this design.

 

 

[Selexus]

I'm with you Steve. I challenged our SE about the 250mm slab and he said his calculation fell apart at anything less than 250mm. On this design every 25mm of concrete is £1k  😲

The exiting concrete (and the substrate) is absolutely fine (as confirmed by a Geo Technical survey).

Blinding has been dispensed with as the existing slab has a 10mm variance across it's entire 57m length with a good surface finish (used to be a chicken shed).

 

 

I'm committed to this design now as any more delays and my build program goes seriously off track, but I'm definitely with you on the over engineered observation.

On the bright side, I should be able to use the telehandler indoors 🤣

Anyway i've just sent the SE an email asking about the reinforcement build up as to my sums we have 170mm of reinforcement with a 50mm bottom spacer, which leaves me with only 30mm of top cover (i think) 🤨

 

Why is nothing every simple.......

Edited August 3 by Selexus

[JohnMo]

Don't leave your car keys in the ensuite and realise when your in the garage. That's one long walk. Thought ours was bad at 25m.

[Selexus]

2 minutes ago, JohnMo said:

Don't leave your car keys in the ensuite and realise when your in the garage. That's one long walk. Thought ours was bad at 25m.

 

Bugger.....hadn't thought of that. It's a 57m walk.....

 

Scooters....electric scooter....that's the solution 😃

[JohnMo]

4 minutes ago, Selexus said:

It's a 57m walk.

114m as you need to pick up keys and then walk to car again. Plus the other 57m wasted. No need for the gym

[saveasteading]

Green raft insulation. Is that Greenguard?  I wasn't aware of this bug just looked it up.

Makes sense to have extra strong insulation when under such heavy load as must be being designed for.

180mm of this appears to cost £48/m2.

 

I wonder if your SE has made the slab thick just to match the beam, and to spread the beam load wider over the insulation.

 

My stingy take on this is to have no insulation under this industrial floor and add extra elsewhere. Ground isn't a bad insulater anyway.

 

I'd love to see the calc's for this slab  as there is something I'm not grasping. OR the SE isn't great on value.... most aren't... only me and @Gus Potter.

 

[Nickfromwales]

Ok, so we’ve covered that your SE is on crack, but at least your floor won’t suffer the same way. We can set this lunacy aside now I guess. But I just like to say, after seeing the 100mm substructure, (expletive deleted) me down!!! 😳. Space x has a new home for next launch lol. 
 

Right. Back to UFH. 

Just go on top as going under and then dropping a Titanic amount of steel on top of the pipe is fraught with danger. If the pipe gets damaged you’d have to lift it all out, replace the pipe run, and go again. And repeat.

 

[Selexus]

1 hour ago, JohnMo said:

114m as you need to pick up keys and then walk to car again. Plus the other 57m wasted. No need for the gym

*selexus goes to look at Samsung watch step app*