Radon gas risk assessment condition

[Drellingore]

2 minutes ago, Gus Potter said:

Where are you building?

 

Kent, north of Folkestone. My username is the location... Although I should have pretended to be Dr. Ellingore!

 

2 minutes ago, Gus Potter said:

Why are you replacing the existing concrete slab?

 

It's very old, very not-flat, and we need to insulate under it otherwise we lose a lot of space. That's my understanding anyway; I tend to take the wife's word and the architect's word on such matters.

 

2 minutes ago, Gus Potter said:

You should by this time have an SE fully on board giving you practical building advice and showing you where the costs lie in terms of buildability, working closely with your Architect, guiding them and encouraging design discussions.. unless you want to lose money. 

 

We do. They're saying radon is outside of their remit. 

[Gus Potter]

47 minutes ago, Drellingore said:

It's very old, very not-flat, and we need to insulate under it otherwise we lose a lot of space.

Ok, that sounds like a valid reason. You have a height restriction.

 

49 minutes ago, Drellingore said:

We do. They're saying radon is outside of their remit. 

That's flag if they can't take this in their stride then oh dear! Radon is assocaited with granite rock. 

 

My gut feeling is that you are not paying your SE enought. Phone them up and have a frank conversation. Don't be afraid to step on your Architect's toes. 

 

Just say they ask you for an extra two or three grand to hold your hand. All they need to do is to save you a week of two men's skilled time on site + expenses. And how much are you going to spend! 

56 minutes ago, Drellingore said:

tend to take the wife's word and the architect's word on such matters.

Then she should have told you to be the bad ass and knock heads together. 

 

[saveasteading]

Radon is simple. Maps show the risk level, by postcode even. If it needs protection it's a standard membrane and easy while constructing. If not, then not.

But don't ignore it.

 

Have you tried to put less insulation over your existing slab, and then balance it elsewhere?

The rules can be adjusted too, esp as this would be a 'sustaimable' option ie not buying concrete.

Are you looking at a few cm of problem or a lot?

 

[Drellingore]

Ergh. BGS survey came back with >30% probability, so that'll be full mitigation.

[saveasteading]

£1.50/ m2 and no normal dpm needed,  or am I missing something?

[Drellingore]

26 minutes ago, saveasteading said:

am I missing something

 

Full mitigation means sumps and the like, as far as I understand? Again. Mx. GPT reckons this is a few grand, but the architects and Visqueen imply that it'll be non-trivial.

Edited 2 hours ago by Drellingore

[saveasteading]

1 hour ago, Drellingore said:

means sumps and the like

Perforated pipe with gravel surround will catch this theoretical gas and vent it. A plastic chamber each end. Radon barrier above.

Complexity will vary acc to your construction method.

 

I'd have to check why the radon is expected to somehow get through the barrier so needs venting.

 

A holistic solution shouldn't cost too much.

 

 

 

OR. Believe the people trying to sell you stuff.

 

I've built about 60??? Buildings in Kent some very near you,  but none needed radon measures. I feel that the sales opportunity/ designer caution has increased over time.

I'm unaware of any issues arising in buildings without it...eg most of your neighbours.

 

Can you find out what anyone else locally is doing? That will give you precedent.