radon barrier

selfbuildsoon

Finally starting the raft foundation next week and it's come to my attention that you can get a better radon barrier than what the local builder suppliers have priced for. As we're in an area of high radon should we put it in? (builder says as we have a raft there's no real need) One of the types I've heard of is monarflex- are there any other good ones?
Thanks.

Max Moment

Ignore what your builder says - you definitely need a Radon Barrier. You will be installing a DPM layer under your raft anyway. For an extra few euro you can install a decent combined radon barrier and DPM. The monarflex RMB 400 is one of the best around but there are many others available depending on the application etc.

Considering that you state you are in an area of 'high radon' it may be beneficial to call in a specialist contractor who can advise on your exact requirements and needs to protect you from the Radon Gas. Especially noting detailing around any awkward junctions on your build. They will also lay the barrier and seal it and also provide you with certification. There is a lot more to it than just rolling out a roll of plastic.

It would be naive to think that by installing a radon barrier that you will prevent all gas from penetrating to your property. But with a fully sealed barrier, adequate Radon sumps installed (and possibly external extract fans if needed) it will certainly significantly reduce any exposure.

Hope this helps

muffler

^ ^ Good post.

selfbuildsoon

Thanks for that. Will go for the better option so and I'll feel happier.

sas

Max Moment wrote: »

Considering that you state you are in an area of 'high radon' it may be beneficial to call in a specialist contractor who can advise on your exact requirements and needs to protect you from the Radon Gas. Especially noting detailing around any awkward junctions on your build. They will also lay the barrier and seal it and also provide you with certification. There is a lot more to it than just rolling out a roll of plastic.

I used rmb400 for my home and I can't agree more that you need specialists to fit it. Once you get to any type of a corner it's very difficult to work with due primarily to it's thickness and rigidity. We ended up using the regular black radon membrane to form corners and joined them to the rmb400. Nothing wrong with this on paper I'm told. If I was doing this again I'd gladly hand this job to someone who knows how to do it.

Radonman

A few things to note here too, probably the most important thing to remember here is to install a Radon Sump prior to the pouring of the raft foundation (trust me it happens - then the head scratching starts) this is a common oversight as people are all concentrating on getting the raft right.
Try to have all you pipes in place prior to installation to avoid puncturing the barrier at a later date.
For the best results from a Radon Barrier ensure all the joints are welded(taping does not work in the Irish climate)and its a Reinforced Barrier not the other glorified polythene membranes (i refuse to call them barriers).
I agree with the above responses - get suitable installers to fit it but price around as prices can vary.
To keep your installation cost down try where possible to have all the internal walls level with the backfill / hardcore / trunking this avoids uneccessary internal corners and ensures a better installation

selfbuildsoon

So would the RMB 400 be suitable or have you any other recommendations?

Radonman

selfbuildsoon wrote: »

So would the RMB 400 be suitable or have you any other recommendations?

RMB400 is probably the best on the market but you will pay a premium for it and the installation (as it is more rigid), the next best imo is the Duraskrim white barrier and comes in a lot cheaper - plus it does not shrink or elongate on hot days as it does not absorb heat (this is a problem believe it or not) - I'm going building in the next month and its the Duraskrim I'm gonna use, installed correctly its perfect and I'm building in a very high Radon area - hope this helps

selfbuildsoon

Thanks, will look into the Duraskrim also.

tred

selfbuildsoon wrote: »

Thanks, will look into the Duraskrim also.

Also look at incorporating a ventilation system into the new build, by exchanging the air within the house, your also dumping out any gas that "might" get in bringing in clean fresh air from outside.

selfbuildsoon

We're going with heat recovery definitely.

manufan16

I hope you don't mind me hijacking your post!
I was looking for peoples opinions on best place for radon barrier- in between hardcore & concrete slab or above concrete slab before insulation and screed?

Thanks

Radonman

manufan16 wrote: »

I hope you don't mind me hijacking your post!
I was looking for peoples opinions on best place for radon barrier- in between hardcore & concrete slab or above concrete slab before insulation and screed?

Thanks

Both are correct but by laying a Radon Barrier directly on to a concrete slab it will definitly get damaged from lumps / loose conc in the concrete plus the friction from people walking on it, this can be avoided by a light covering of sand to act as a buffer. In my opinion inbetween the hardcore and the slab is the best option, just make sure the hardcore is well compacted with sand on top - the added bonus of this is that its covered quickly lessening the chance of damage