Do I need a radon barrier or will a normal DPM do for my raft?

 

Tanners, in their raft design for me, a "Radon barrier / DPM" is shown as a layer between the heave protection and insulation and they state "Radon sump to be provided in accordance with architects drawings and specification."  And the fellow who will be building my raft has said I need to supply the radon barrier if needed.

 

But, checking the Public Health England webpage on Radon shows the area of my plot (Cambridge, UK) has a "Maximum radon potental" of less than 1%, which is the lowest in their scale.

 

(I know the Tanners are in Ireland and, from reading other BuildHub posts on the subject that Radon is assumed over there.)

 

 

14 minutes ago, Dreadnaught said:

Do I need a radon barrier or will a normal DPM do for my raft?

 

Tanners, in their raft design for me, a "Radon barrier / DPM" is shown as a layer between the heave protection and insulation and they state "Radon sump to be provided in accordance with architects drawings and specification."  And the fellow who will be building my raft has said I need to supply the radon barrier if needed.

 

But, checking the Public Health England webpage on Radon shows the area of my plot (Cambridge, UK) has a "Maximum radon potental" of less than 1%, which is the lowest in their scale.

 

(I know the Tanners are in Ireland and, from reading other BuildHub posts on the subject that Radon is assumed over there.)

 

 

I think Tanners foundation drawings are standard and everything's in, until its not. There is nothing to lose by using a radon barrier rather than a standard DPM. Pennies difference.

 

I think radon measures as referred to in levels, I.e. level 1 protection required = install a radon barrier. Level 2 = radon barrier and sump pump.

 

It looks like you don't need the sump pump, and chump change to use a radon barrier as belts and braces if you are so inclined.

Thanks @LA3222. Makes sense.

I think radon can go straight through polythene it is a very small and inert atom. Best ventilate under any membrane 

radon can also come from made up ground. Check your planning conditions to see if it was specified, if not dont bother.

Building control will request radon barrier if it's needed in your area. 

 

In Ireland most areas are "radon action" areas so radon mitigation is assumed... Tanner's are Irish so no surprise it's a standard detail in their drawings.

4 hours ago, Dreadnaught said:

Do I need a radon barrier or will a normal DPM do for my raft?

...

 

There's a map of the Radon areas of the UK here. It's self-explanatory : you're either in a Radon area or not. If not - guess what - ya don't need a radon barrier, unless as @Dave Jones says you have a condition specifying you need it.

If you do, and if you need a sump ( as we did) nobody came to inspect it, nobody checked that we have an external vent, nobody could give a stuff.

 

Except if you get irradiated by enough Radon, you die early.