Studwork / UFH

[DaveH]

Apologies if this has been covered many times.

 

I have a slab lower ground floor and block and beam upper ground floor. I have found conflicting advice on whether to install studwork first and then lay insulation, UFH and screed, or insulate first, lay pipes, take lots of photos and measurements, screed and then fit studwork. What is generally considered the best approach? I can see positives and negatives to both ideas.

 

Thanks,

[Dudda]

Put in the insulation, slip membrane to stop screed getting down between joints in the insulation or tape the joints, UFH pipes and then screed. It's very simple and easy to just spray paint or mark out with masking tape on top of the slip membrane/plastic where the internal stud walls and kitchen units are going and then just keep the UFH pipes away from these areas.

Edited November 22, 2018 by Dudda

[Russell griffiths]

You also don’t need to screw into the floor to erect your stud walls, just glue your bottom plate down with no nails. 

[nod]

2 hours ago, DaveH said:

Apologies if this has been covered many times.

 

I have a slab lower ground floor and block and beam upper ground floor. I have found conflicting advice on whether to install studwork first and then lay insulation, UFH and screed, or insulate first, lay pipes, take lots of photos and measurements, screed and then fit studwork. What is generally considered the best approach? I can see positives and negatives to both ideas.

 

Thanks,

Always studs first

[Nick1c]

I would imagine it depends on your floor finish. Our (current) plan is to power float the slab to give the finished floor. The up side is not paying for additional tiles/timber & less time/money power floating as there will only be four edges and four corners. The down side will be ensuring accurate measurement of where the walls will be for fixings and protecting it during the build. 

If you put timber on an un insulated slab are you setting yourself up for cold bridging problems?

[nod]

2 minutes ago, Nick1c said:

I would imagine it depends on your floor finish. Our (current) plan is to power float the slab to give the finished floor. The up side is not paying for additional tiles/timber & less time/money power floating as there will only be four edges and four corners. The down side will be ensuring accurate measurement of where the walls will be for fixings and protecting it during the build. 

If you put timber on an un insulated slab are you setting yourself up for cold bridging problems?

I fix studs everyday for a living 

Never on top of UFH 

 

As Russ has already pointed out You can glue the sole plate down 

 it usually as a change of plan 

Get them down and run a rip of ply aroun the bottoms 50 mil higher than the floor level 

 

 

[DaveH]

So far one vote for each method ?

 

I guess there isn't particularly a correct and incorrect way to do it - just positives and negatives to weigh up.

 

Studs first, I would have concerns about cold bridging and I would want to protect the bottom of the studs from the screed.

 

Studs after, obviously you need to know where the UFH pipes are, although just gluing the sole plate down eliminates risk of puncture. I would however need to locate the UFH manifolds and take account of some first fix plumbing and wiring so at least one wall would have to go up prior to the screed.

 

Finished floor surface will be a combination of tile and timber.

 

[Ed Davies]

Friend did an oak-frame extension (basically a one-bed house less the kitchen) on insulated beam and block (Hanson Jetfloor). Put the concrete, UFH and screed down before the oak frame was constructed, let alone the internal studs. His builder was very sceptical but after seeing it work did his own extension the same way.

 

The only problem they had was a change of design to the stairs needed for compliance with some fire rules which resulted in the newel post moving to somewhere they weren't absolutely sure there wasn't a pipe. IIRC they were 90% sure of the positions but checked by turning the heating on and using an IR thermometer as it started to heat up.

 

I think they just left the pipes a bit long where they came out of the screed and temporarily fixed the manifold to some bits of timber while the screed went down. Easy as the manifolds were in what was to become the glazed link to the old part of the house; would have been a bit more awkward if it was in the middle of the building.

[JamesP]

I have just fixed 1200 metres of UFH pipe on the ground floor , screeders booked for next week. I would recommend doing the studwork first for all designated rooms with their own

zone. For the kitchen I measured  and marked where the island and units will sit after screed applied. 

 

[Redoctober]

Our studs went in first and we even glued one set of studs as this was fitted after the screed was poured. You will see from the images, the bottom of the studs are protected and the manifold is already in place.  Hope this helps.

 

[TerryE]

7 hours ago, nod said:

Always studs first

 

This is a safe and conventional solution, but with the usual hassles of laying the screed on a per room basis which induces level issues etc.   Quite a few of us have gone for a single-slab approach which requires a more competent crew and tighter quality standards -- which is probably an ask too far for most builders.  See @Stones and @JSHarris blogs for examples of this approach used successfully.  In my case the upside was that the entire slab was flat to within a few mm over 11m, and was cheaper too.  But either way you really need to have your floor plan fixed and accurate to ~1cm IMO, and that includes where your doorways and any fitted units and cupboards are going to go.  Any variations as @Russell griffiths says will need to rely on gluing.

 

@Redoctober, I am not sure why you took your pipe runs so close to the room boundaries .  For example in your hall I would have stuck with 9 instead of 10 runs.  Your wallside runs look about 50mm from the CLS.  By the time that you've boarded up and fitted the skirting your it looks like your carpet fitter will be nailing his gripper rods in directly over the pipe runs.  Maybe you should consider using adhesive grippers  

[Ed Davies]

7 hours ago, TerryE said:

For example in your hall I would have stuck with 9 instead of 10 runs. 

 

Dunno, but I suspect there might be certain mathematical elegance to having an even number. ?

[PeterW]

33 minutes ago, Ed Davies said:

 

Dunno, but I suspect there might be certain mathematical elegance to having an even number. ?

 

... or you need both a flow and return......

[DaveH]

Thanks to everyone for the input

[TerryE]

2 hours ago, PeterW said:

or you need both a flow and return......

 

Durrhhhh, up too late. But still, ending up with the outside runs so close to the wall is asking for trouble, IMO.  I would keep it to an absolute minimum of 100mm, even if you move runs over 1 click.

 

 

[Ferdinand]

2 hours ago, PeterW said:

 

... or you need both a flow and return......

 

Dunno.

 

Before long the Worm Man may be a statutory consultee demanding one run be subterranean to provide a non-frozen winter sanctuary for the Lumbicinae.

 

F

Edited November 23, 2018 by Ferdinand

[Redoctober]

16 hours ago, TerryE said:

 

 I am not sure why you took your pipe runs so close to the room boundaries .  For example in your hall I would have stuck with 9 instead of 10 runs.  Your wall side runs look about 50mm from the CLS.  By the time that you've boarded up and fitted the skirting your it looks like your carpet fitter will be nailing his gripper rods in directly over the pipe runs.  Maybe you should consider using adhesive grippers  

 

Rest assured @TerryE the floor area in the middle section and to the right are being laid with stone tiles, so no problems in that regard. As for the floor are to the left, that will be carpeted and our UFH installer was aware of this. We were more than happy with the spacing as it was more generous than it appears. As for 9 runs instead of 10, I can't really comment other than the installer knows more about this sort of stuff than me and if he felt it needed 10, then who am I to argue. But I suspect @PeterW is correct with his suggestion.

 

8 hours ago, PeterW said:

 

... or you need both a flow and return......

 

[Moonshine]

O.k i am going to resurface this thread.

 

My gut is saying that its easier (cheaper) for the screeders to work on larger areas with minimal amount of corners, so its my plan to lay the insulation and UFH pipes then screed without putting up stud work.

 

Before the screed goes down, i will have marked on the masonry external walls where the free areas are for the partitions, so i can use this as a marker plus measurements and plans to situate the sole plates

 

Once the screed has cured, bolt / screw down a sole plate timber to the screed in the free partition areas, using bolts that are limited to 40mm in a 75mm deep screed, maybe glue the sole plate to the insulation for good measure! 

 

What could go wrong ?

[Nickfromwales]

Logistical ball-ache, plus you’ll still have to incorporate breaks in the screed for expansion anyway so 6 and two 3’s tbh.

Screeders are used to laying screeds in whatever spaces are there, and they will typically use a 8’ or 10’ bar max normally as anything bigger is physically problematic to use by hand. 

[Russell griffiths]

I’ve just finished mine, I laid pipes over entire floor area, then screened whole floor incorporating expansion joints to fall in doorways and under a long run of wall. 

All my stud walls are up without one single screw or bolt into the screed, all glued down with HB42 adhesive 

[Conor]

Another bump.

 

We've now got the ground floor slabs in over the basement. I want to get cracking with a few pre-watertight jobs in the basement, like stud walls (treated timber) and first fix MVHR and plumbing.

 

What's the detail for building up a stud wall from the subfloor? I have a load of lightweight blocks... Can I build up from a course of them?

 

Or if I start the studs on the slab (presumably with DPC), would I need noggins at FFL for fitting skirting etc?

[Conor]

On 22/11/2018 at 21:36, Redoctober said:

Our studs went in first and we even glued one set of studs as this was fitted after the screed was poured. You will see from the images, the bottom of the studs are protected and the manifold is already in place.  Hope this helps.

 

 

What are you studs built up on? Concrete sub-floor? Mind sharing the details?

[dpmiller]

All our walls sit on a course of quinnlites.

[Russell griffiths]

What topping is going on the sub floor. 

 

You can use a double or triple  bottom plate. 

Depends what the build up is. 

[Conor]

1 hour ago, Russell griffiths said:

What topping is going on the sub floor. 

 

You can use a double or triple  bottom plate. 

Depends what the build up is. 

175mm PIR and 75mm S&C screed (or 200mm PIR & 50mm liquid, tbc). So actually @dpmiller suggestion of the thermal blocks then soleplate is perfect.

Edited November 17, 2020 by Conor