Raft Foundation radon barrier

I was hoping some of you could solve a discussion a number of us were having, In a raft foundation is the radon barrier supposed to be above or below the mounds ?? Is there a disadvantage in one way over the other. Incidentally i had it installed over the mounds

sydthebeat

Do whatever the iab cert from the radon barrier says.

homewardbound11

Radon we below the mounds if I remember my build

Metric Tensor

I've seen both and up until last year I would have said it was horses for courses. With the mounds on top you have to be very careful about hidden punctures.

But with the 200mm layer of T2 Perm - the permeable fill that is required by IS888 - it seems to make sense to have it directly above this layer (appropriately blinded with T3).

Still nothing "wrong" with it being over the mounds because your 200mm permeable layer will still be below it to collect the radon.

Where is your 200mm T2 layer relative to the mounds?

Metric Tensor

Metric Tensor wrote:

Still nothing "wrong" with it being over the mounds because your 200mm permeable layer will still be below it to collect the radon.

Metric Tensor wrote:

But with the 200mm layer of T2 Perm - the permeable fill that is required by IS888 - it seems to make sense to have it directly above this layer (appropriately blinded with T3).

The membrane is above the mound. There was some holes from installing steel which I repaired.

I was thinking of putting another membrane above the raft if needs be.

B-D-P--

We just recently went above, Soley because the Engineer insisted.
However with a raft foundation, Radon will be doing well to get through the concrete never mind the barrier.