Radon Barrier in old stone house

FP Peking Duck

Has anyone successfully put a radon barrier in an old stone house?

From researching this, and reading previous posts, I gather that the radon barrier should extend beyond the external walls. Makes sense, thereby the gas will hit the barrier and have no where to go except outside I presume? Easy in a new build.

But how do you slip a barrier under 2 ft thick stone walls?

The inside of the external walls will be drylined with a gap between the stud and the stone wall. Would bringing the barrier up behind the stud suffice. I'm guessing not, since the space betwen the stud and the wall will be airtight (in theory)....so I'd just get a build up of gas in there.

Would a sump do?..
Would I put in a sump, put down the radon barrier instead of the DPC...extend it behind the stud...or what?

Thanks.

ircoha

what kind of floor have u in mind?

sinnerboy

this may help

http://www.environ.ie/en/DevelopmentandHousing/BuildingStandards/PublicationsDocuments/FileDownLoad,1656,en.pdf

FP Peking Duck

The old floor was a floating timber floor..ie there was about 1 foot gap below the joists...brick supports built up every few feet...and ventilated to the outside.

I took all this up and whats there now is a mixture of old rubble, dust, lime plaster, powdered sand and cement, old bricks etc. etc. Its fairly level and even...and is almost sandy at this stage.

I will be pouring new concrete floor slabs, insulation, DPC, UFH as per normal....

Some other queries...would I be OK to lay the new slab on top of whats there? or should I put in a layer of hardcore and then a layer of sand?...would I have to remove this rubble first...

I was advised to put insulation down first (on top of whats there)..then pour the slab...and then insulate again between the slab and the UFH screed...

Do you think it would be necessary to do the first insulation under the slab?

When the UFH screed is set, I'll be drylining all the external walls...if that makes any impact on the radon barrier question.

The plan is to seperate the internal dividing walls from the external walls...so that the drylining runs interrupted, to stop bridging.

ircoha

have u seen this to give u an idea of what the risk is
http://www.rpii.ie/radon/maps/clare.html

depending on where u are perhaps a ventilated suspended concrete floor would be the business: look at homebond manual for the methodology.

In passing how are u dealing with the attic conversion: is it a trussed roof or a cut roof?

FP Peking Duck

Thx.
On the roof..One wing of the house is single story. This is the bit I'm converting. It has ceilings about 14 feet, so I'm lowering these to make it easier to heat. That gives me a lot of workable space on top. The roof is pitched, with the cross ties (?) currently at wall level. These will be moved up closer to the apex to create walkable space underneath. Roof is over 100 years old. Timbers are sound with 10 by 5 purlins (the ones running along the roof supporting the rafters...??) about 25 metres long with 2 internal supporting walls (with chimneys in) evenly spaced.

FP Peking Duck

Thanks for the links. Seems my best option is a sump or sumps. Since the floors are being relaid I can lay sumps and pipes. Is putting in a barrier a waste of time since I can't cover the entire building footprint (can't get under the existing walls).

FP Peking Duck

FP Peking Duck wrote: »

Thanks for the links. Seems my best option is a sump or sumps. Since the floors are being relaid I can lay sumps and pipes. Is putting in a barrier a waste of time since I can't cover the entire building footprint (can't get under the existing walls).

A sump & pump should remove a substantial amount of radon (preventing it from entering the rooms above), it really depends on what the levels are before you start.

doyler2

Have you had the house tested to see what the levels are like in it before you go and spend all this money and effort to try and keep the radon out?
There may not be any radon under the building in the first place.

If you have then it would be more worthwhile installing a sump before you pour new floor slabs. Maybe contact one of the radon companies around the country for advise on how to best get rid of the problem.

If you are changing windows and sealing the house up them make sure you test afterwards, as this can increase the radon levels dramatically. Most people think that because they have a sump, or a sump and a barrier installed that they are protected from radon which is very misleading. A sump does nothing until it is activated, and if the barrier gets punctured or is not sealed 100% then radon will get drawn through it.

There is a product that can be used to seal radon barrier to the inside of a wall. It is like a 12" wide piece of radon tape that sticks to the wall, and also seals to the barrier.