Underlay with underfloor heating? Correct type?

hellopaul2 · 11 Dec 2018

Hello,
Long story short: I am about to complete the purchase of a 3-storey house with underfloor heating (wet type). I'm currently trying to delay completion (due to complete tomorrow - Wednesday) because I suspect the builders (it's a new build) have put in standard underlay, not one suitable for underfloor heating. I pulled up a bit of carpet and took a couple of photos:
[GALLERY=media, 102300]Underlay1 by hellopaul2 posted 11 Dec 2018 at 6:36 PM[/GALLERY][GALLERY=media, 102299]Underlay2 by hellopaul2 posted 11 Dec 2018 at 6:36 PM[/GALLERY]
You may also notice that they've used nails, not glue, to secure the gripperrods. Nails in the floor is always a winning combination with heating pipes

.

So, I'm interested to hear whether "people in the know" think that this is bog standard underlay, or one suitable for underfloor heating. I'd guess the underlay is about 8mm thick, and does not feel very dense. It's not the rubbery type. The ground floor is cement/concrete, and the first and second floors are chipboard.

Unfortunately the seller's solicitor is spouting a pack of lies and it's all getting very nasty. I'm trying to delay things and get the builder to rectify it, or at least confirm that it is suitable underlay (which, we all suspect, it's not).

So I'd be interested to hear any thoughts?!

dazlight · 11 Dec 2018

Duralay king is good for underfloor heating.

The one you have could be ambience by tredaire which has a high tog so not ideal but can still be used.
The lower the tog the more the heat will travel through.

As for the grippers the nails won’t go through the chipboard to reach a pipe.

hellopaul2 · 12 Dec 2018

@dazlight Thanks for your reply. I suspected the nails wouldn't go all the way through the chipboard into the pipes - let's hope they haven't used extra long ones! I'm still planning to (probably) replace the underlay with something more suitable, and then have the joy of suing the builder for the costs (they've admitted the underlay is not suitable already! It's been a catalogue of ****wittery resulting in a total ****tangle).

dazlight · 12 Dec 2018

Who built the house. So many corners cut in new builds these days.

hellopaul2 · 17 Dec 2018

I'm not overly worried about the build itself; I know corners are cut, but from what I can see the house seems to be reasonably built (my family was in building for many years so I can recognise shoddy workmanship when I see it). It was a local builder, not a big developer. Tragically, I was lumbered with a trio of tosspots handling the purchase (my solicitor, their solicitor, the estate agent) - I won't go into details here because I intend to pursue all of them so they pay up. I know solicitors and estate agents are usually pretty low down the pecking order when morals or brains were being handed out, but these ones were waaay at the back of the queue. So basically the situation arose from each of these three stooges ballsing up and blaming the other, while nothing actually happened in terms of progressing the purchase.

Haha - I've just seen your signature line - do it right, do it once. If only more people stuck to that, I wouldn't be in the situation of potentially having to do the underlay a second time!

crazydaze · 21 Dec 2018

Ideally the UFH should have a tog rating that the floorcoverings including underlays should not exceed, maybe worth getting the specs of the UFH and the underlay/carpet they have fitted to see if the system has been over loaded. Also, check the make of the underlay to ascertain if the manufacturer specifies it for UFH use.

If the Underlay and carpet Tog rating is in specs with the floor, and the Underlay is suitable for use over UFH then all should be ok.

We tend to use Duralay Heatflow in most of our carpet over UFH installations.

hellopaul2 · 22 Dec 2018

Another question on this same installation - is it normal to glue the carpet to the underlay? That's what's happened in this case, and it's not something I've seen before. I'm slightly concerned that if I pull up the carpet and underlay, I'll end up with chunks of underlay stuck to the back of the carpet, or, even worse, chunks taken out of the carpet backing.

crazydaze · 23 Dec 2018

hellopaul2 said:
Another question on this same installation - is it normal to glue the carpet to the underlay? That's what's happened in this case, and it's not something I've seen before. I'm slightly concerned that if I pull up the carpet and underlay, I'll end up with chunks of underlay stuck to the back of the carpet, or, even worse, chunks taken out of the carpet backing.

It’s normal to use some spray adhesive on the perimeter edge of stretch fit installations especially if the carpet was stiff when fitted as this helps the carpet to stay on the gripper in such situations.

It’s unusually to fully stick a secondary back carpet in domestic installations but not unheard of.