Floor insulation

Slates

I've been looking info on differing types of floor insulation

The usuall build-up is

Hardcore
Sandblinding
Radon barrier
Insulation
another layer of visqueen
Concrete

What is the second layer of visqueen for ??

Builderfromhell

Never heard of anyone putting Radon/DPM layer and 2nd layer of Visqueen. However, if you were putting UFH pipes in concrete it might help to stop concrete seeping between cracks in insulation and causing cold bridging. Also, it could temporarily keep rain off insulation and stop it flating in downpour. Agin, I've never heard of 2 layers of DPM.

Jimbo

You'll probably be looking at either AeroBoard or something more sophisticated such as Kingspan Thermafloor or Xtratherm. Depending on the perimeter/area ratio of your house you'll need about 70mm of the Kingspan or Xtratherm or 120mm plus of AeroBoard. Dont think theres many other options other than rigid

sydthebeat

jimbo78 wrote: »

You'll probably be looking at either AeroBoard or something more sophisticated such as Kingspan Thermafloor or Xtratherm. Depending on the perimeter/area ratio of your house you'll need about 70mm of the Kingspan or Xtratherm or 120mm plus of AeroBoard. Dont think theres many other options other than rigid

and just remember, those thicknesses quoted above will probably allow you to meet the MINIMUM u values required... perhaps think about upgrading to 100mm PUR or PIR. Also ensure your builder installs 25mm upstands all around your external walls (again this is minimum, you should put them around all walls)... and also ensure his first course of partial fill board insulation in the cavity starts 225mm BELOW the finished floor level.

and i would agree with previous posters that a second DPM course is NOT required.
If you are installing UFH pipes, you would be better off with this construction

Hardcore
Sandblinding
Radon barrier
100mm concrete subfloor
100 mm PUR Insulation
65-75mm concrete screed with pipes in corporated (or easy screed type)

muffler

sydthebeat wrote: »

65-75mm concrete screed with pipes in corporated (or easy screed type)

That doesn't allow much cover on pipes. 100mm should cover all situations.

Slates

sydthebeat wrote: »

and i would agree with previous posters that a second DPM course is NOT required.

Why is this details on both the kingspan and quinn therm brochures then?

I've never seen it used on a site anywhere but it is is a requirment on the details................it is also called building paper

Mellor

Its on the details as it was a requirement under BS 1521.
Which is now out of practice. The paper/membrane wasn't required to be a DPM, it was of a much lower gauge. It was used with in-situ floor to keep water from the concrete in location while the slab cured. If the water ran off into the insulation the slab could potentially been weakened, and insulation may not preformed optimally.

sydthebeat

Slates wrote: »

Why is this details on both the kingspan and quinn therm brochures then?

I've never seen it used on a site anywhere but it is is a requirment on the details................it is also called building paper

http://www.insulation.kingspan.com/uk/pdf/k3.pdf

Have a look a figure 1 for the standard build up.

Mellor

sydthebeat wrote: »

http://www.insulation.kingspan.com/uk/pdf/k3.pdf

Have a look a figure 1 for the standard build up.

???
Take another look at that PDF, the second sheet is included just as Slates said, and the document refers to BS 1521, just as I said.

sydthebeat

muffler wrote: »

That doesn't allow much cover on pipes. 100mm should cover all situations.

Not necessarily required. Depends on manufacturers specification, and in most case 65-75 mm screed is recommended.
http://www.floorscreeding.co.uk/html/under_floorheating.html
This system recommends 75mm.

Most easy screed systems recommend only 20mm over the top of the pipes, thus generally 50mm for them.

Obviously the less concrete that has to be heated first, the quicker the response time to heat the ambient air in the dwelling. The main disadvantage of UFH is the response time, thus every effort should be made to reduce it.

sydthebeat

Mellor wrote: »

???
Take another look at that PDF, the second sheet is included just as Slates said, and the document refers to BS 1521, just as I said.

good point, only noticed that now... perhaps the foil backed nature of similar products negates the need for this breather paper.

heres the IAB cert for xtratherm flooring insulation
http://www.xtratherm.com/pdf/XTUF.pdf

theres no breather paper course required here.

ardara1

Slates wrote: »

I've been looking info on differing types of floor insulation

The usuall build-up is

Hardcore
Sandblinding
Radon barrier
Insulation
another layer of visqueen
Concrete

What is the second layer of visqueen for ??

Hi Slates - using a 2nd layer over the top of all insulation in recommended by the BRE Good Practive Guide on flooring - it acts as a spearating layer between hardcore and insulation stopping brdging between boards when being laid.

The radon barrier can double up as you damp proof membrane to the underside (It stops gas and moisture) - ALL floor must have this layer BELOW the insulation - if moisture penetrated thru' the boards, or the joints, the heat loss is through water not insulation.

Mellor

sydthebeat wrote: »

good point, only noticed that now... perhaps the foil backed nature of similar products negates the need for this breather paper.

heres the IAB cert for xtratherm flooring insulation
http://www.xtratherm.com/pdf/XTUF.pdf

theres no breather paper course required here.

Its not breather paper realy, its to keep moisture of the boards from the concrete pour.
Its not a requirement (unless covered by a new BS), but it certainly is best practice as Ardara pointed out. It is often a lower gauge than the DPM, as it doesn't need to double as a radon barrier

sydthebeat

is it still a DPM course?? or is it hydroscopic??
i wonder in that make up where the condensation point is.....

If it turns out to be good practice, it will suit me because i certified a similar construction recently, on which i was a little apprehensive about....

clint_eastman

I came across this thread on a search for floor insulation and am interested to hear peoples opinions on the floor make-up now given that this was from 2 years ago.

I'm using a contractor to bring up my substructure, I'm planning on putting in 100mm Kingspan TF70 over the DPM and pouring a 150mm slab on top of the insulation, I hadn't heard of this 2nd layer of a lesser guage and was wondering if there's any best practice updates out there?

Wolfhound14

I am also interested on any updates in the last few years. Just lodged planning so I'm trying to do some research.

clint_eastman

I found this other thread link here

But its also from a while back.... i guess I'm really only looking to hear if there's an update on the idea of using a 2nd layer of plastic to mitigate against issues arising from a reaction of the foil backed insulation with the concrete that I'll be pouring on it...

Based on what i've seen here already, it looks like it would be a good idea....although at an additional cost

sydthebeat

clint_eastman wrote: »

Based on what i've seen here already, it looks like it would be a good idea....although at an additional cost

for about €100... and youd get it rolled out over a standard sized dwelling in a couple of hours.

clint_eastman

yep agreed, and I'm sure I will do this....

although every little bit counts just means a smaller turkey i guess....