Pbb

Underfloor heating installation opinions on work quality

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Hi,

We have just had a new underfloor heating system installed and would like some feedback on the quality of work. 

We have a retrofit installation with insulation panels that has traces in it. Soon there should be a latex screed going down but the company doing the screed has said they cannot do anything until the insulation boards have been stuck down and the edges sealed so the boards don't float up.

When the board were put down no adhesive was used, is this normal?

Also the boards were not cut to the shape of the rooms and gaps were left. On the advise of the screed company the plumbers were asked to come back and fill them in as a huge amount of screed would be needed to fill them.

The guys came back and filled in the gaps with boards they cut in to random piece and put in but again did not fix down.

Finally they used some expanding foam around the edges but the board lifted due to not being stuck down.

Anyway I have included some pictures to let you see for yourselves.

Thanks 

https://ibb.co/St199JD

https://ibb.co/svWfn1T

https://ibb.co/7vC4MKv

https://ibb.co/xjJmBr0

https://ibb.co/5WBZQgh

https://ibb.co/TKhrChX

https://ibb.co/hsGkkMB

https://ibb.co/fpxDKKd

16138507902753275613574881066887.jpg

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It’s not good, so cancel the screed until this is resolved.

 

how thick is the insulation?

is there any up the sides of the walls on the external walls.

 

have you looked at the manufacturer instructions for the system that’s installed? That will give you specific info to discuss with the ‘plumbers’

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Ouch. That’s shocking. 
The suppliers are usually able to do a route map when supplying with sections / pipe ways / crossovers all avoided etc so this should have been relatively neat and organised. 
The boards absolutely must be bonded down, don’t even DREAM of pouring screed over that, it’ll be a train wreck. 
Pipes will have to come up, boards up, and redo I’m afraid 😟. There is no quick fix here. 

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1 hour ago, TonyT said:

 

is there any up the sides of the walls on the external walls


This needs to be set around the perimeter Link to allow the screws to expand and not push directly against the walls. 

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Thank you all for your replies. 

We had though it would be a case of redoing the job and it is a great help to have it confirmed. 

@TonyT the board are about 25mm some are against the wall with no perimeter tape/insulation.

@NickfromwalesI am pretty sure they had a route map with them when they started the job.

I have had a good read up on what is involved and prepared to have a discussion with the plumbers as to what has to be done now.

 

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On 20/02/2021 at 21:30, Nickfromwales said:


This needs to be set around the perimeter Link to allow the screws to expand and not push directly against the walls. 

 

Screed?

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Are you tiling over the screed? If so consider forming expansion gaps where two areas of screed meet at doorways. Otherwise there is a chance of getting a curved crack that can propagate through the tile. With a straight expansion gap you can tile upto it or put a cill piece over it.

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What a waste of materials if it has to come up.  They normally start with a perimeter upstand of insulation that slows heat transfer to the walls and allows expansion in the screed.

 

I can see why it will be difficult to liquid screed.  Could they use a solid overlay like ScreedBoard 20?  It can be tiled and is a dry application that you could even DIY.

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Taking a step back, has there been any heat loss calculations for the system design?
It looks like all the pipes are being laid on uninsulated bare floor, with a tiny slither of insulation squashed in around them.  I assume this is because of limited height to ceilings, and lack of desire to dig out the floor to reduce depths and do the job properly.
The result is going to be 50% of your heating bill going into the ground under your house rather than heating the house itself. Unless that's what you really want, you really should think about abandoning this and using something fit for purpose like a wall hung radiator.

 

(IMHO retrofits designed like this should be illegal under building regs)

 

 

image.png.3ab88ffffc316b1dcd39c647ff428e1f.png

 

image.png.d728761add7bfa3fba45e19f4b0ab7fe.png

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18 minutes ago, joth said:

(IMHO retrofits designed like this should be illegal under building regs)

 

I agree.  I think that this should be covered in the regs and some minimum standard applied.  I know several people who get a new kitchen, a bit of building work (like chimney out) and underfloor heating with little / no insulation.

 

The problem is the hassle and expense of taking up an existing floor, which neither the builder nor the householder wants to do.  If it costs an extra hundred a year to heat, they may never get their money back.

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I don't believe that any of these overlay systems are worth a toss. The only way i would consider any overlay would be floorboards up, 100mm pir between joists, floorboards back, then 20mm pir over floorboards, glued down. pipes layed on top, and then 40mm screed. Even then i doubt it would be great. I would be going for either modern rads, or trad rads, depending on the style of house. In my opinion, with what you have got there you are going to need the heat on 24 hours a day to get a decent amount of heat into the house. Sorry, but i'd be scrapping that. I think you are heading for a big disappointment.

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Get digging!

 

SAM_0431

 

SAM_0472

 

SAM_0535

 

SAM_0569

 

SAM_0636

 

SAM_1086

 

SAM_1087

 

SAM_1093

 

SAM_1634

 

SAM_1824

 

Edited by Onoff
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@TempWe have an engineered oak floor going down over most of it and tile in the kitchen.

@jothAs far as we know all the calculation have been done to qualify for the RHI. We don't know why the areas were left where the pipe was put directly on the floor? The only reason we can come up with was they were too lazy to cut the boards properly. If I had done the job myself I could easily have made all the boards fit the area without the need for anything to touch the ground.

As far as digging out the floor, we did that ourselves before the plumbers even got started. The house heats up very well with this system in and retains a lot of the heat.

 

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33 minutes ago, Pbb said:

The house heats up very well with this system in and retains a lot of the heat.

 

 

Nobody is suggesting it won't heat up. Just that it would likely heat up quicker and retain more heat, as well as using less fuel if there was more insulation in the floor. Underfoot I'm sure it feels lovely. Similarly your "boiler" might last longer if it's working less. 

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as others have said, you need really 150mm of insulation and 75mm of screed on top of that to do the job properly or to building regs. This additional 225mm would mean you would hit your heads when walking through internal doors which is why the floor has to come out first.

 

Honestly you will be better off with rads.

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2 hours ago, Pbb said:

@jothAs far as we know all the calculation have been done to qualify for the RHI.

 

This maybe the problem,  unfortunately this doesn't actually mean anything for UFH.  RHI has no minimum requirement for insulation below ground floor, only for loft and cavity walls. Moreover, the worse the EPC, the higher the RHI payments, creating an absurd reverse incentive to insulate as little as legally possible. Which is all well and good until the RHI payments finish and then the customer is left with a needlessly expensive to run system.

 

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23 hours ago, Big Jimbo said:

I don't believe that any of these overlay systems are worth a toss. The only way i would consider any overlay would be floorboards up, 100mm pir between joists, floorboards back, then 20mm pir over floorboards, glued down. pipes layed on top, and then 40mm screed. Even then i doubt it would be great.

 

I had exactly this done and it was still poor. I had to turn the flow up to 60C to heat the room (not a such problem when you have radiators running that hot anyway)and loads of the tiles cracked.

 

Personally I think the problem is that suspended timber floors with air blowing under them are not a great starting point for a UFH system.

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