Insulation for UFH

whitelightrider

Hi folks,

We are looking at putting in the UFH downstairs and rads upstairs in our house. The plumber is hoping to start next week. I have 2 questions:

1) How much and what kind of insulation should we put under the UFH?

2) Should we put down insulation upstairs before the screed goes in?

yop

What type?? Well we put down 4" of insulation on the ground floor.
What have you upstairs? Hollowcore is it? Not sure if you need insulation on that, but I have no experience though.

sydthebeat

whitelightrider wrote: »

Hi folks,

We are looking at putting in the UFH downstairs and rads upstairs in our house. The plumber is hoping to start next week. I have 2 questions:

1) How much and what kind of insulation should we put under the UFH?

2) Should we put down insulation upstairs before the screed goes in?

1. you should aim to have a u value of the floor of 0.16..... if you can stretch the budget, put in 150mm rigid PU insulation.

2. Yes. about 40mm here would be suficient.

PS, why are you installing two heating systems?? ie rads and UFH.....

whitelightrider

yop wrote: »

What type?? Well we put down 4" of insulation on the ground floor.
What have you upstairs? Hollowcore is it? Not sure if you need insulation on that, but I have no experience though.

Hi Yop,

Just wondering what other people are putting down. Is it ordinary fibre glass that you put down?

We have hollowcore in the house as well so we may not need to insulate the floors upstairs.

whitelightrider

sydthebeat wrote: »

1. you should aim to have a u value of the floor of 0.16..... if you can stretch the budget, put in 150mm rigid PU insulation.

2. Yes. about 40mm here would be suficient.

PS, why are you installing two heating systems?? ie rads and UFH.....

Hi syd,

1) Excuse the stupidness of this question, but if I was to walk into the hardware this weekend what would I ask for?

2) 40mm of ordinary fibre glass?

Also I spoke to a guy selling UFH at the Selfbuild in Galway and he advised this. He told me that upstairs you are looking for quick bursts of heat to heat the rooms before bed. He said that it would take too long to heat the room with UFH and he would advise using Rads upstairs and UFH downstairs.

We're at the stage now aswell where we are looking at either gas or oil to heat the house. So any advise on this, and on the boilers we should be looking at would be greatly appreciated.

sydthebeat

150mm Kingspan Thermafloor or
150mm Xtratherm Thin R or
150mm Quinntherm QF or
150mm Ballytherm


above the slabs, you need a rigid insulation, not a quilted one... so 40mm of any of the products mentioned above

whitelightrider

sydthebeat wrote: »

150mm Kingspan Thermafloor or
150mm Xtratherm Thin R or
150mm Quinntherm QF or
150mm Ballytherm


above the slabs, you need a rigid insulation, not a quilted one... so 40mm of any of the products mentioned above

Thanks syd.
So just to ensure I have this correct.

We put 150mm of insulation onto the raft. Lay the UFH heating on top of this and then poor the screed?

Also upstairs we just lay 40mm on top of the hollowcore?

sydthebeat

whitelightrider wrote: »

Thanks syd.
So just to ensure I have this correct.

We put 150mm of insulation onto the raft. Lay the UFH heating on top of this and then poor the screed?

Also upstairs we just lay 40mm on top of the hollowcore?

Yes, thats what i would do.

dont forget the radon membrane / DPM.....

sunnysoutheast

whitelightrider wrote: »

Hi folks,

We are looking at putting in the UFH downstairs and rads upstairs in our house. The plumber is hoping to start next week. I have 2 questions:

1) How much and what kind of insulation should we put under the UFH?

2) Should we put down insulation upstairs before the screed goes in?

Hi - this is the same setup as we have.

D/S - 2x50mm Kingspan, polythene on top, then UFH pipes and then screed. Don't forget the edge insulation.

U/S - hollowcore floors, screed, radiators/towel rails, underlay and semi-solid oak.

Not sure why you'd put insulation under the screed upstairs if you're not putting in UFH upstairs.

We have two condensing boilers on mains gas, BTW. One does the UFH only and the other does the rads and DHW.

I gather if you use a single heat source for UFH and rads you need to oversize the rads because of the lower temperature needed for UFH or that you get out of geothermal.

SSE

whitelightrider

sunnysoutheast wrote: »

Hi - this is the same setup as we have.

D/S - 2x50mm Kingspan, polythene on top, then UFH pipes and then screed. Don't forget the edge insulation.

U/S - hollowcore floors, screed, radiators/towel rails, underlay and semi-solid oak.

Not sure why you'd put insulation under the screed upstairs if you're not putting in UFH upstairs.

We have two condensing boilers on mains gas, BTW. One does the UFH only and the other does the rads and DHW.

I gather if you use a single heat source for UFH and rads you need to oversize the rads because of the lower temperature needed for UFH or that you get out of geothermal.

SSE

Hi SSE,
Thanks very much for that. Ill take a look at this and see how I get on with the hardware this evening. What type of insulation would I use for the edges?

bauderline

For the edges I used 60mm Xtratherm Thin-R ....

whitelightrider

bauderline wrote: »

For the edges I used 60mm Xtratherm Thin-R ....

Cool. So I can head to the hardware and order this stuff so. 2 x 50mm Kingspan for the main floor and 60mm Xtratherm Thin-R.

Cheers guys.

sunnysoutheast

It was 50mm Kingspan I think.

There is a little booklet you can get from builder's providers from Kingspan and you can get pdfs from Xtratherm's website which detail the various approved construction methods - however I'm not sure if they've been updated with the new building regs. which, dependent on your planning approval date, you'd have to adhere to in order to get signoff.

We also put Xtratherm insulated plasterboards on all external walls BTW. If you're thinking of doing this decide now as it has impacts on skirting, sockets, switches, cabling etc. Also you may get a better deal on buying all the insulation in one hit (you'd need somewhere secure to store it in the meantime otherwise it'll get stolen).

SSE

sunnysoutheast

whitelightrider wrote: »

Cool. So I can head to the hardware and order this stuff so. 2 x 50mm Kingspan for the main floor and 60mm Xtratherm Thin-R.

Cheers guys.

You might want to check that you are building to an approved construction method and that you comply with the new building regs. before you go ordering! Who's signing the build off?

As Syd says you might be better putting in 150mm under the UFH, we only used 2x50mm as we sourced this cheaper than 1x100mm. I'm not sure of the new regs. as they depend on perimeter ratios etc.

SSE

bauderline

You should be able to download and use builddesk for free, it will allow you to play with insulation specs and determine u-values.

It takes a little time to figure out how to use it and what materials to use.

Also be warned.... it no like Vista !

baud.