Underfloor heating in screed

[samwilko]

I ve just run all of the underfloor heating circuits in a barn conversion for a customer. It's a polyplumb solid staple onto cellotex before screed system. The owner has now come back to me and said they are building a fireplace in the lounge and don't want any pipes underneath it. I was told the location of the slate hearth in the lounge so avoided laying pipes under this. It now turns out I was told wrong, hearth is much larger than original plan and is having a granite surround built on it accommodating a solid fuel log burner.
they want the underfloor heating pipes moved out from under where the new larger hearth will sit a they are concerned about the weight of it on the screed with underfloor in it. Moving the underfloor pipes is easier said than done. Is it necessary for them to be moved?

 

[townfanjon]

Imo , the fire / hearth could do with being on its own footings and lay the screed and pipes around it, that way neither will cause any potential problems with the other

 

[Ermintrude]

My slate hearth is inset. I have run the ufh into the builders opening so slate is always warm.

Really some people are numb. The screed and hearth will spread out weight.

Also the downward force of the hearth acts at 45d through the screed so if it's 65mm you better make sure there is nothing in that 65mm curtailment.... Wouldn't want it crushed under the 300kg spread over 2m2!

Idiots

 

[townfanjon]

Are you calling me numb Guy , so he puts everything on top of the screed ... Logburner, granite etc , And it cracks and goes **** up and the screed company say bye bye, i know what i would do pal

 

[Gray0689]

We never run under a hearth

 

[townfanjon]

We never run under a hearth

I thank you

 

[Ermintrude]

It's not going to crack! The celotex is good for well over 100kg/m2

Wasn't calling u numb. Just custards are ballache. They should pay for alterations?

 

[Gray0689]

It's not going to crack! The celotex is good for well over 100kg/m2

Any design for underfloor I've ever seen or done shows to leave out for a hearth would be

I honestly can't tell you why as I've never had the need to question it

I've had to leave out a gap in underfloor pipework for a grand piano also lol

 

[snowhead]

I'd say leave the pipes as they are, as Ermi said the weight will be spread unless whoever is fitting the fire has made it a condition of warranty that there are no pipes under the hearth.

If they do have to be moved then its all the floor up and new continuous pipes, joins will be a greater risk than the pipes being crushed.

I'd guess there is more load on a single chair leg than there is from a hearth and fire.

 

[Ermintrude]

Ha ha ha . Did u cut it and add crack bars round support columns and allow for the thermal exp?

Worst floor I've ever seen was 25mm thick in places mclp popping up all over - visible through screed and cracked to bits where staircase was onto the floor

 

[townfanjon]

Plenty opinions knocking around , i think the decider is to talk with the screed company and tell them exactly whats going on, they will or should answer your question

 

[samwilko]

The screed hasn't gone down yet, I wouldn't even be entertaining it if it had. It's just a ball ache I could do without to be honest, there isn't enough hours in the day as it is without having to change stuff, unnecessarily in my opinion. But he s insisting the builder wants them moved, which is a pain but worse than that he's saying he told me the size of the hearth, he did, but not this new larger one they appear to have conjured out of nowhere.

 

[samwilko]

The screed company is non existent, it's a hand mix by the builders on site. Between them and a customer who changes his mind every 5 minutes I can see this job being a particularly stressful one

 

[snowhead]

Get the builder to mark exactly where the hearth is going.

Without the screed down it shouldn't be too difficult to loose the extra pipe.

 

[Ermintrude]

Hand batch.... Sooo 1992

 

[ShaunCorbs]

The screed hasn't gone down yet, I wouldn't even be entertaining it if it had. It's just a ball ache I could do without to be honest, there isn't enough hours in the day as it is without having to change stuff, unnecessarily in my opinion. But he s insisting the builder wants them moved, which is a pain but worse than that he's saying he told me the size of the hearth, he did, but not this new larger one they appear to have conjured out of nowhere.

if there paying hay do what ever they want

 

[samwilko]

I can only assume they re mixing it that way as access is very very limited to the site.

 

[joni os]

Confirm pressure test results with client before screed goes down and recommend protection from wheelbarrows while screeding.

 

[townfanjon]

Sam, it sounds like your customer hasnt a clue, UFH screeds arent sand and cement mixes, they are a special mix ( sorry i cant remember the spec or name ) it will be a pain moving the pipes but if its the customer who keeps changing his mind , he should understand he had to pay extra. As for the builder laying the screed ....... I bet he never gets it level lol

 

[Chalked]

Builders, builders, builders.

Why spend loads on labour to hand lay a sand and cement screed. Very hard to get level, cracks and only has partial contact with the ufh pipe.
Anhydrate screed is more expensive, but goes down in a couple of hours and can be walked on in a couple of days. Better thermal properties too.

If the screed has not gone down yet, gt the gusto met to mark the outline of the hearth, then move the pipes, re-pressure test and then educate your builder into the 21st century.

All the best.