Underfloor Heating - Help needed!

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Sunshine12

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I really hope someone can help, I'm slowly going crazy!..

We've got 170m2 of under flooring heating to fit upstairs in our new build but can't figure out the 'best' & cheapest way.

Metal web/easi joists with 22mm chipboard. Planning to use 150mm mineral wool between joists.


Majority of quotes include the aluminium clippa trays/grove chipboard/extra...we want to avoid these due to the extortionate cost. All we want is the pipe & clips due to such a large area = ££

My second question is is it better to install the UFH under the chipboard or over the top? Surely the chipboard blocks the heat? Then we've got ply & tiles to go over the chipboard or wooden flooring.

Can we clip the UFH pipes to the chipboard underneath? Or should we batten 2x1 on top of the chipboard then lay the UFH pipes & then a thin layer of ply followed by floor covering?

Don't know anyone who has UFH let alone in new joists! Obviously we can't drill or notch the joists so need to find a solution.

Please help!!

Ps not scared of the labour (fitting ourselves) so don't mind diy solutions
 
Look at NuHeat's LoPro10 solution - it's laid on top of the timber floor, very easy to install and works well with all floor coverings
 
Underfloor heating is great, low running temperature so low running costs. So for a system to run at a low mean water temperature you need thermal mass. The optimum first floor system would then be a thin weak concrete mix/biscuit/pug encasing the pipes & with the top of the biscuit in contact with the underside of the chipboard flooring.

Firstly ensure your joists are strong enough to support the additional weight of the biscuit, then fix 50x25mm straps along either side of the joist, lay insulation between the joists, cut lay & fix 12mm OSB between the joists. The top of the OSB should be 40mm from the top of the joists, to accommdate the 40mm biscuit.

Fix the UFH pipes with nail clips to the OSB, generally two runs per joist bay will do if your house is a well insulated gaff. Pressure test the system & screed the biscuit.
Ensure the biscuit is completely dry prior to laying the chipboard.
 
PullerGas said:
Underfloor heating is great, low running temperature so low running costs. So for a system to run at a low mean water temperature you need thermal mass. The optimum first floor system would then be a thin weak concrete mix/biscuit/pug encasing the pipes & with the top of the biscuit in contact with the underside of the chipboard flooring.

Firstly ensure your joists are strong enough to support the additional weight of the biscuit, then fix 50x25mm straps along either side of the joist, lay insulation between the joists, cut lay & fix 12mm OSB between the joists. The top of the OSB should be 40mm from the top of the joists, to accommdate the 40mm biscuit.

Fix the UFH pipes with nail clips to the OSB, generally two runs per joist bay will do if your house is a well insulated gaff. Pressure test the system & screed the biscuit.
Ensure the biscuit is completely dry prior to laying the chipboard.
Click to expand...

Consisely put mate.
And OP: you will have to notch the joists to receive the loops and the return and for more than one circuit back to the manifold.
 
dilalio said:
PullerGas said:
Underfloor heating is great, low running temperature so low running costs. So for a system to run at a low mean water temperature you need thermal mass. The optimum first floor system would then be a thin weak concrete mix/biscuit/pug encasing the pipes & with the top of the biscuit in contact with the underside of the chipboard flooring.

Firstly ensure your joists are strong enough to support the additional weight of the biscuit, then fix 50x25mm straps along either side of the joist, lay insulation between the joists, cut lay & fix 12mm OSB between the joists. The top of the OSB should be 40mm from the top of the joists, to accommdate the 40mm biscuit.

Fix the UFH pipes with nail clips to the OSB, generally two runs per joist bay will do if your house is a well insulated gaff. Pressure test the system & screed the biscuit.
Ensure the biscuit is completely dry prior to laying the chipboard.
Click to expand...

Consisely put mate.
And OP: you will have to notch the joists to receive the loops and the return and for more than one circuit back to the manifold.
Click to expand...

You know in my own modest way, I'm not just infamous, I must be one of the best.

I'd bore the joists in the correct location & double feed the loop through.
 
PullerGas said:
dilalio said:
PullerGas said:
Underfloor heating is great, low running temperature so low running costs. So for a system to run at a low mean water temperature you need thermal mass. The optimum first floor system would then be a thin weak concrete mix/biscuit/pug encasing the pipes & with the top of the biscuit in contact with the underside of the chipboard flooring.

Firstly ensure your joists are strong enough to support the additional weight of the biscuit, then fix 50x25mm straps along either side of the joist, lay insulation between the joists, cut lay & fix 12mm OSB between the joists. The top of the OSB should be 40mm from the top of the joists, to accommdate the 40mm biscuit.

Fix the UFH pipes with nail clips to the OSB, generally two runs per joist bay will do if your house is a well insulated gaff. Pressure test the system & screed the biscuit.
Ensure the biscuit is completely dry prior to laying the chipboard.
Click to expand...

Consisely put mate.
And OP: you will have to notch the joists to receive the loops and the return and for more than one circuit back to the manifold.
Click to expand...

You know in my own modest way, I'm not just infamous, I must be one of the best.

I'd bore the joists in the correct location & double feed the loop through.
Click to expand...

Double feed?
 
Pex Al Pex is great pipe for UFH. If you 'spoon' the ends you can generally get two runs in between even joists at 400mm centres.
 
In spite of the slight cost I would still be inclined to use one of the metal spreader systems with a shallow depth of screed as that gives quick heat up.

Tony
 
Agile said:
In spite of the slight cost I would still be inclined to use one of the metal spreader systems with a shallow depth of screed as that gives quick heat up.

Tony
Click to expand...

How would you use a spreader plate system and then screed it? Or more importantly why would you do that? o_O
 
Thanks for all the comments.

The clipper plates are circa £5 each plus screws/fixings and we need 300+ so obviously we wanted to look for other solutions to have a couple of grand!

Would it be possible to clip the piping to the underside of the chipboard (from below) & then 150mm mineral wool insulation underneath. Feed the pipes through the metal webs. Joists are spaced at 600mm.

Problem fitting from above is we would have to cross batten the deck which raises the floor height as we cannot drill/notch the metal web joists unlike traditional joists.

Yes very labour intensive but fitting ourselves. Any problems with this method?

Thanks to those who genuinely tried to help
 
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