NickTellis Registered User

Will (hopefully) be given planning permission for a sizeable extension to my 1960s bungalow but am wondering how the radon barrier will be put down in the extension and how it will work as (I'd imagine) the rest of the house doesn't have one? I'm a bit concerned that the new barrier will "push" any radon into the rest of the unprotected house.

sydthebeat Subscriber

If you are worried about radon being 'pushed' into the existing house then what you should do is fit a radon sump and pipe to the path. Then fit an extractor fan onto this pipe to suck any potential radon away.

perhaps get a radon measurement done in the existing house to see if radon is actually a hazard?? it may not be.

budo73 Awaiting Email Confirmation


what part of the country do you live in?
Radon is generally not an issue in certain parts of the country and a problem in others. You can get a map from the government showing you where problem locations are.

Regardless of what you do, the fact that your existing house doesn't have a radon barrier means that if radon is present it will get into your living space through the slab in your existing house - this means that a radon barrier in the extension is of no purpose.

If you are not in a problem are I wouldn't worry about it. If you are then get a measurement taken as the previous poster suggested.

RKQ Registered User

Check out the map:-

IMO Radon is a naturally occuring gas. Its everywhere but it is at dangerous levels in certain areas, as shown on the map.

I wouldn't worry about the existing - it exists.
But the extension is new build. Why not ensure the extension complies or exceeds the requirements of the Building Regulations. Ensure it is radon free.
Install a quality dpm and a radon sump.its not very expensive!

When do you hope to build? A radon test can take 6 months on site.(Special disk left exposed in room / house for 6 months, then posted to RPII for test results.)


Client doing an extension and builder has suggested that as my client's house is sitting in a limestone area that she should get the whole house radon-proofed.

The RPII map shows 1-5% and my ltd knowledge suggests that granite is the main 'carrier'. Am aware how the map is constructed.

All geological comments welcome?


Mellor Registered User

Granite is the main carrier, limestone has potential also.

I really hate that map, its there to warn people. Instead it gives a flase sense of security.

The radon that enters you house comes from directly below.
Consider the are of a square on the map, Its 100 This is huge, its 100 million sq.m
The area below your house might be 200-300 sqm (footprint plus 50% say). So a granite deposit here has a huge effect on you, yet little on the whole "square"

/rant over.


Tks for reply:

The subliminal import of your post is perhaps, if in doubt test, a suggestion I agree with.

doing a bit more exploration it seems there are two ways to test:
one is use a testing centre in Ireland which charges 95 euro a test ( 3 months)
the other is get a gizmo from US that works ( collects data every hr) for 5 years for 119 usd (110volt but...)

Anyone any thoughts?

In passing: the language on both sites is a tad alarmist,
the following is from the irish testing site:

Radon barriers are very unreliable, particularly under building site conditions. Studies to date indicate that up to 50% of barriers installed in Ireland are ineffective.

Interesting that this sort of a claim can be posted

RKQ Registered User

A sump costs €30 plus a few lengths of pipe. Less than €100 to be safe.

So its possible to put in a preventive meassures for less than the cost of the test! IMO its best to put in the sump and heavy guage dpm, sealed etc.

I imagine radon soaks in like a slow heavy fog, as its heavier than air. Therefore the sump in the extension might help remove the radon from the existing house. I understand Radon is everywhere but is only dangerous at certain levels in certain areas.

I'd put in the sump and assume there is radon and build accordingly - what have you got to loose by being cautous?

Want to share your thoughts?

Login here to discuss!