Floors & Floor Insulation

Podgemcd

Hi all. Can anyone help me with this one. At present we are building our new home and I have a few questions. First of all I will tell you the order in which we have laid the materials:

1 Foundations with Steel
2 Block work to hardcore level, blinded with sand
3 Radon Barrier, (the radon barrier was laid completely flat over this hardcore)
4 a 12" block to FFL. 5" of subfloor was poured inside this.
5 100mm xtratherm insulation
6 UFH Pipes
7 3" of concrete with fibres on top of UFH pipes.

I have a few questions:

After the subfloor was poured over the radon barrier, the 100mm insulation was fitted. It rained for a solid 2 weeks on this and about 0.5" of water was present under the insulation when i checked. I told the builder and he bored holes out into the cavity and swept the water out through these holes. Rehau Polythene was then laid over this insulation and then UFH pipes.
Is there any problems with leaving these holes in the blocks open? They are 7" below FFL now.

Screed is now poured on top of all this and awaiting block layer. This poses another question: When we put the first floor slabs in place, the ground floor slab should get a chance to dry. Would this then leave it so that we could lay timber floors soon after completion?

Thanks in advance for any help!

sinnerboy

Too late now - but you should have completed the shell - i.e. roof timbers on , felts + battens and windows in before insulating and screeding your ground floor

You cant let PIR slabs get so wet - they absorb water , devaluing performance.

Your floor u value , with UFH must be 0.15 - 100mm may achieve this - but I doubt it ( depends of floor area / perimeter ratio )

Not to mention that your screed surface is now vulnerable to damage during the remaining heavy works.

How long has your builder been building ?

Carlow52

OP:
a few questions:

what cavity?
Did the holes go through the radon barrier?

U now have holes 7" below ffl: what level is the ground outside relative to the holes?

do u have perimeter insulation in the screed floor?

ur ufh pipes that are above ground need to be well protected, end taped etc

On drying: 1" a month after the house is weather proof.

once house is airtight but before doors etc are fitted u could rent a dehumidifier to help the process but use with care, if u over do it u could warp any timber

Podgemcd

Thanks for the replied guys.

The builder is in the business for 40 years believe it or not! I thought that we would have a roof on before the UFH pipes and Screed was poured but I was assured by the engineer that it was ok to go this way!..... Maybe he does not really know?! The plan is to lay plywood down in all ground floor rooms to protect the finished screed.

As for the water being drained into the cavity. This is way above the radon barrier. The radon barrier is in tact. the water was drained off into the 100mm cavity between the inner and outer leaves of the outer wall. Should I now go and fill these holes bored by the builder.....?

Podgemcd

Thanks for the replies...

The ater was drained into the 100mm cavity between the inner and outer leaf.
Holes did not go through the radon barrier. Radon barrier is way below this.

Holes are now 7" below FFL on the inner leaf only. Paths will be 6" Below FFL. Grould level will be 3-4" below this again.

I have perimeter insulation in the screed floor, on outer walls only. Inside walls were not done with this. Screed as far as I could see was just standard concrete with fibres in it.

The UFH pipes abobe the ground are already in the manifold. We have 1 small wall build indide the house to mount the manifold on.


Would it be a good plan to use a dehumidifier before door frames and stairs go in? All windows and outside doors are PVC.

Carlow52

Am not an expert on radon/DPC layers but any details I have seen always seem to have the radon barrier or/and the dpc lapped up inside the inner face of the inner leaf as far as the level of the finished floor.

Thus am confused as to how u can have holes 7" below FFl that dont go through either the dpc or radon and that are still visible.

The other point is that any details I have seen have the cavity filled up to top of dpc: some builders use solid blocks upo to top of dpc.

will try post a link to some details

Again am no expert so hopefully someone else with have an answer.

Use the dehumidifier with care as I dont want u to warp the roof timbers opr any internal stud timber walls.

If all the skimming internally is done then u could use one with care.

Podgemcd

The Radon barrier was fitted completely flat over the sand blinding and dropped down one level of blocks to the outer leaf. A 12" block was then laid on this barrier and 5" of concrete was poured over this barrier, leaving the blocks protruding 7" out of the subfloor. This is where the holes are bored. Hope that clarifies the situation!!

As for the cavity, ours is completely empty under the FFL. Would it be advisable to fill it up to FFL with concrete?

sydthebeat

Podgemcd wrote: »

The Radon barrier was fitted completely flat over the sand blinding and dropped down one level of blocks to the outer leaf. A 12" block was then laid on this barrier and 5" of concrete was poured over this barrier, leaving the blocks protruding 7" out of the subfloor. This is where the holes are bored. Hope that clarifies the situation!!

As for the cavity, ours is completely empty under the FFL. Would it be advisable to fill it up to FFL with concrete?

podge....

id be worried about the ability of your builder...

it is absolutely much better practise to give the radon membrane an upstand at external walls....

to lay it flat out either shows the builder has assessed the radon danger on the site as per RPII measures.... or he was lazy....

in this last 7" he is going to put 4" pu board, the 1200 gauge dpm, then 3" screed...

Carlow52

Podgemcd wrote: »

The Radon barrier was fitted completely flat over the sand blinding and dropped down one level of blocks to the outer leaf. A 12" block was then laid on this barrier and 5" of concrete was poured over this barrier, leaving the blocks protruding 7" out of the subfloor. This is where the holes are bored. Hope that clarifies the situation!!

As for the cavity, ours is completely empty under the FFL. Would it be advisable to fill it up to FFL with concrete?

Have a peep at the details here [ link as promised]
http://www.environ.ie/en/Publications/DevelopmentandHousing/BuildingStandards/FileDownLoad,18751,en.pdf

which is on here: http://www.environ.ie/en/TGD/

Podgemcd

thanks for all the useful info guys. I have spoken with my engineer this morning and he is aware of all progress to date. I know there can be some deviation to "recommended practice" but I will be putting my foot down from now on if I see something I don't like.