radon

[Sal]

hi - haven't been about for a bit - busy with lots of house and land projects!
We have just had our radon test back and its over the acceptable level, so need to do something about it - preferably something that is compatible with respecting an old house. our house is constructed from granite (radon? who'd of thought it) with solid floors, a rayburn and open fire (to be replaced with woodburner in future) with single glazing and lots of drafts (plan to put in DG at some point)
Contrary to popular belief - its not just the modern sealed houses that have radon issues. Also the gumpf that came back with the test results indicate that open fires and flues of the not balanced type make the situation worse - sucking more of that radon filled air in - whereas I had imagined it clearing out the stuff.

So I am thinking - a sump with fan vent is the way to go. any opinions? any experience? anything i should avoid?

thanks in advance.

Sal

 

[Nemesis]

Not about radon no - but why replace windows (unless modern and not nice) when simply doing something about draughts would help hugely?

 

[Gervase]

A sump is the commonest way of dealing with the problem in older houses, as radon is heavier than air and will always find the lowest point. The sump solution only works with solid floors, though. If you've got suspended floors you may need to install a fan system.
The BRE has some information on radon here. What you need to do depends largely on how far over the 'acceptable' level your readings are.

Any for anyone wondering about their own locality, the Health Protection Agency's Radon Atlas of England and Wales, which breaks the risk down into postcode areas, is a 2.2Mb download on this page.

 

[Gervase]

...the radon issue is one area where BCOs can and do cause problems if you want a breathable floor, as they can insist that an impermeable radon barrier is used.
Here in West Wales the radon risk varies depending on the underlying geology, but the BCOs will generally stipulate the dreaded red plastic sheeting unless you can argue convincingly with reference to the radon atlas - and in some cases you have to fork out for an NRPB test to prove conclusively that you don't need the radon barrier.

 

[Sal]

Not about radon no - but why replace windows (unless modern and not nice) when simply doing something about draughts would help hugely?

the windows we have at the moment are wooden, and look ok, but are not the original sashes. I plan to put in the same with DG, and the reason is to spend alot less money and fuel on heating the place (saving on our expenses and hopefully helping save the planet etc )and adding some sound proofing (not much but it all helps) given are window is right on the street. we are doing what we can about draughts,, but to be honest most of it is the windows and front door which is also glazed. We have heavy curtains but they are not much use during the daylight hours.

 

[Sal]

What you need to do depends largely on how far over the 'acceptable' level your readings are.

our test came in at 280 and the 'action threshold' is 200. average for the country is 20. so not as bad as it could be, but we would like to get it pretty low.. not just acceptable.

 

[biffvernon]

Also the gumpf that came back with the test results indicate that open fires and flues of the not balanced type make the situation worse - sucking more of that radon filled air in - whereas I had imagined it clearing out the stuff.

I think that may be true with a suspended floor, where the fire may suck air up from the space below the floorboards. With a solid floor I can't see how the increased ventilation needed for a fire can do anything but improve the situation so long as there is plenty of free ventilation from the outside and you don't create negative pressure that sucks air (and radon) from the ground.

 

[andrew gayton]

a limecrete floor will impede radon....................

 

[Penners]

With a solid floor I can't see how the increased ventilation needed for a fire can do anything but improve the situation so long as there is plenty of free ventilation from the outside and you don't create negative pressure that sucks air (and radon) from the ground.

If radon is permeating out of the ground inside the house, won't it be doing the same outside? So, arguably, sucking external air in would bring more radon in with it. Wouldn't it?

Or have I misunderstood the physics?

 

[Lime]

With a solid floor I can't see how the increased ventilation needed for a fire can do anything but improve the situation so long as there is plenty of free ventilation from the outside and you don't create negative pressure that sucks air (and radon) from the ground.

If radon is permeating out of the ground inside the house, won't it be doing the same outside? So, arguably, sucking external air in would bring more radon in with it. Wouldn't it?

Or have I misunderstood the physics?

Radon is a heavy inert gas that has a half-life of 3.8 days and then becomes polonium, a short lived metal.
As it's a heavy gas then taking air into the house from high up would reduce the radon intake I would have thought.

 

[Sal]

well firstly - our ground floor which is solid - is lower than outside, so its like we are living in a sump - so I guess the radon will be coming in sideways as well as from ground.

and secondly - all of the bumpf with the radon results said that open fires flues and chimneys were a problem - in fact if you had an unused chimney you should cap it and seal it up. this is the opposite of what I imagined and I don't quite get it as one of the ways to reduce your radon levels is to increase ventilation....
is it back to that negative pressure thing?

 

[biffvernon]

If radon is permeating out of the ground inside the house, won't it be doing the same outside?

No, it just blows away. Concentrations outside are very low.

all of the bumpf with the radon results said that open fires flues and chimneys were a problem - in fact if you had an unused chimney you should cap it and seal it up. this is the opposite of what I imagined and I don't quite get it as one of the ways to reduce your radon levels is to increase ventilation....
is it back to that negative pressure thing?

It comes down to the path taken by the air that gets sucked up the chimney. If a low pressure is created inside the house there's the risk of sucking up the radon. You need to allow plenty of free ventilation from outdoors so that this doesn't happen.

An impermeable plastic barrier in the floor is probably needed.

 

[Sal]

An impermeable plastic barrier in the floor is probably needed.

hmm yeh the barrier method (ahem!) is suggested in the bumpf - but does involve taking up the skirting boards etc as well. and I have to wonder how this will effect the damp situation we already have in the walls. of course our health is most important issue but if I can find a way without doing too much damage that would be good.

still thinking the sump and pump might be the best plan

 

[Penners]

If radon is permeating out of the ground inside the house, won't it be doing the same outside?

No, it just blows away.

Unless you suck it onto the house....?