Radon

[saveasteading]

If you are in a region with granite, there is a strong chance of needing radon protection under the floor, either a special dpm barrier or a ventilation system.

 

I used the government Radon map and it showed the lowest risk category that requires special measures. 

But it was on the edge of the averaged big square so I invested in the online assessment.

It asked for postcode then address from a list and then came back immediately saying 'no radon risk, no special measures .

Specifically "What is the requirement under Building Regulations for radon protection in new buildings and extensions at the property location? - None"

I assume that it uses a much more detailed map than is published.

 

£3.90 spent and many hundreds saved, and a simple certificate for the Building Warrant application.

 

So I recommend others to look at the map on line first , then get this assessment if it appears to be a radon area.

 

 

 

[Jenki]

Thanks for the  heads up on the report ?, I looked at this site and it gave me a 3 - 5% risk, so ordered the report, unfortunately it confirms the Radon Risk

"Guidance for new buildings and extensions to existing properties
What is the requirement under Building Regulations for radon protection in new
buildings and extensions at the property location? - Stage 1"

 

Anybody know what Stage 1 is?

 

They recommend looking at BRE211 - This is £45

There is also  a download "radon protection for new dwellings (gg74 Revised)" for £16 

anybody got a copy of these or extracts knocking around?  Thanks in advance.

 

 

[saveasteading]

Probably not worth researching or buying the documents.

Radon barrier is not horribly  expensive (it used to be, especially when provided by 'specialists'.)

I think it is simply plastic that is dense enough to keep radon gas on the underside.

£1/m2 from screwfix, compared to half that for normal dpm.

 

I didn't realise it was that cheap, or I wouldn't have been so chuffed to find we were unaffected. 

[Jenki]

As you say the cost of Radon DPM is negligible, just wasn't sure I needed to start quoting references etc for the building warrant, never built in Scotland so the Building Warrant is new to me.

[saveasteading]

1 minute ago, Jenki said:

never built in Scotland so the Building Warrant is new to me.

I have but different building type , and the rules of process have changed.

I am working on warrant application and trying to use plain language rather than too many references:  I hope I am right. if i was the BCO I would prefer that.

 

So in my case I am saying...clause 3.2 ,  not required ,   see this paper.

in yours:  is required, see this report, so am laying this product, and show the detail.

 

No radon in Preston after all then.

[George]

Jumping in on this thread, who would normally specify a radon barrier? Is it the architect or building control? 

[saveasteading]

4 hours ago, George said:

Is it the architect or building control? 

Whoever is presenting the design. Architect, Engineer, yourself. Simply look up the definitive website and pay for the information. About £3 if I recall.

Answer emailed in  a few seconds and you simply include that page in your submission.

 

The extra cost of a radon rated dpc isn't as bad as it used to be.

 

http://mapapps2.bgs.ac.uk/geoindex/home.html?layer=BGSRadon&_ga=2.106057667.1323565302.1635198583-1743045500.1633718990

 

 

[the_r_sole]

4 hours ago, George said:

Jumping in on this thread, who would normally specify a radon barrier? Is it the architect or building control? 

 

We always get the specification from the membrane manufacturer 

[saveasteading]

Just now, the_r_sole said:

specify a radon barrier

I see what you mean. Specify as in 'state that it is a design requirement', or specify as in 'choose a manufacturer?

 

AS I understand it, it is simply a dpm where the plastic is right chemically and in thickness that gas with radon in it can't get through.

 

It used to come from very specialist suppliers with 'danger radon beneath here' written all over it in red on yellow. Now it comes from toolstation for £0.70/m2.

 

[the_r_sole]

10 hours ago, saveasteading said:

I see what you mean. Specify as in 'state that it is a design requirement', or specify as in 'choose a manufacturer?

 

AS I understand it, it is simply a dpm where the plastic is right chemically and in thickness that gas with radon in it can't get through.

 

It used to come from very specialist suppliers with 'danger radon beneath here' written all over it in red on yellow. Now it comes from toolstation for £0.70/m2.

 

 

I've had different requirements previously, one where we had to cross ventilate the solum (in a solid floor!) , tape all the joints with service penetrations etc, others where they've just put the membrane in, hence why we generally send the SI report to a specialist to make sure we are compliant with the  BRE guidance (as that's a fun document which doesn't really tell you which protection you need!)

[saveasteading]

2 hours ago, the_r_sole said:

we had to cross ventilate the solum (in a solid floor!) 

Ok I a am a cynic. But whenever I have had a recommendation from a specialist, for methane usually, they have allowed complex ventilation underneath as well as seals, and all to be carried out by a specialist installer.

 

So I looked into this is a big way, as I had several jobs on or near landfill. 

Since then we did it ourselves at about 1/4 the cost. It still needed physical ventilation beyond a certain distance from the outside walls, and in one case (because of distances,)  a constant fan.

The difference in cost, apart from margins, was that plastic pipes came without 'methane pipes by the acme safety company' written on them. ditto the membrane,

 

So by all means get it designed by a specialist, but I suggest diy, or by the builder with close attention to quality.

Ventilation or not will depend on the distance to the perimeter, ie size of building. It is an a fairly accessible document.

 

Perforated pipes under  the building, or ventilate the void, as applicable, with the barrier in place and sealed everywhere. The gas just wants to escape so make it easy