We've just had cavity wall insulation fitted. The installers INSISTED on installing a core vent in our lounge as we have an open fire place, although I have no intention of ever having an open fire.
There is now a draught and ingress of cold air into my lounge!
As I understand it, this infernal thing has nothing to do with cavity wall insulation and is probably a scam to get more money from the government.
However, now I've got it, is there any elegant way for blocking it up? Ideally one which is reversible, should I change my mind about having a fire in my fireplace?
We had a vent in a room that was not needed (nothing to do with gas or other heating/combustion so not at all sure why it existed). I used a piece of 50mm Celotex about the right size and hammered it into place. (Actually, two pieces one on top of the other.) Then a thin sheet of something (hardboard) over - and painted. So dead simple to reverse, effective, easy.
I know I could do the job properly, but it has worked well for over five years now and I no longer notice the hardboard! But it is out of the way in the spare bedroom. And I reckon it is actually a warm patch on that wall.
I don't know if this matters in your situation (in fact it doesn't if you never have a fire!) but in my experience open fires appear to draw an incredible amount of air. The light carpets in the lounge are discoloured at the edges where coal dust has been drawn up from the cellar. In my situation, that's not the worst - I live in a radon area, so I think it's sensible to avoid this type of thing, and I have a window open with an open fire.
Pull the cover off and stuff something in it! A big ball of bubble wrap seemed to do the trick nicely. Might be an idea to put something sticking out of the vent to remind you its blocked.
Surely the logical answer for air supply is a duct from the outside coming up through the floor adjacent to the fire with a simple cover to seal when not in use.
As regards radon, the answer we used in Canada was very simple. Lift basement floor. If headroom is limited dig down about 6", Backfill with gravel. Install vent pipe all the way up to above roof level -- like a soil stack with an open end resting on the gravel. Relay floor using damproofing membrane ensuring concrete cover is solid and ensuring that sealing at the edges is perfect.
The chimney effect of the vent stack is usually enough to ensure that the radon which penetrates from the soil and seeps through the gravel is vented up the stack harmlessly, but to ensure effective negative pressure a small fan is often fitted.
The message from "dennis@home" contains these words:
Agreed, but the idea of the vent pipe with the lower end going through the concrete and dpm (which is sealed to the vent pipe) is that the slight negative pressure in the pipe provides an easy way for the radon to escape and no build-up of pressure is possible. Gas being gas and varying water tables creating pressure, the vent pipe is at least a cheap and effective way of reducing worries.
The message from Frank Erskine contains these words:
The floor in the room in which I am at this moment is indeed solid concrete. And I have a vent. Put it in before we laid the floor :-). What were SDS drills and Stihl saws invented for? :-)
Problems are the cellar is only about 2m (excavation is expensive in Victorian terraces without 'proper' foundations), the house is in a conservation area (restricting external ducts), and the fans (from what I've read) are expensive to run and noisy.
Of course, avoiding radon can be avoided, but it would be expensive in my case. As it happens a recent surevy revealed 2.4 somethings, against an average of 2.0, with an action level recommendation of 200. So I don't *need* the preventative action, luckily.
Excavation doesn't need to go right to the edges, anyway.
We're not talking about anything more obtrusive than a soil stack
In a 2-storey house the fan is probably not necessary anyway. And you can use whatever fan you like. Unless you're battling serious levels of radon you don't need a powerful fan. All you're trying to do is provide an easy way for the radon to esccape harmlessly.
Glad you don't need preventative action. Perhaps there's an incentive to keep the cellar ventilated, though and to seal any crevices through which it might tend to seep.
Incidentally, one thing not mentioned was basement walls. Excavating down to foundation level and backfilling with gravel is a big help in serious cases. Gives an opportunity to tank the basement, too.
No, fair enough, and it could be located at the rear.
That makes sense. I'd read that fans installed in blocks of flats were turned off by the occupants.
I had thought of getting the cellar tanked/tidied/decent ceiling up in any case - but not filled. It's my equivalent of a garden shed and I use it as a workshop. I've made sure the ventilation is clear although there isn't much of a through draft as it's two rooms.
Makes life a lot easier as far as lifting is concerned, anyway.
You could always consider lifting the flags, digging out 6" of earth, keeping 6" away from the outer walls, backfilling with 3" gravel, then sand to avoid perforating the new dpm, then radon quality dpm sealed with radon tape (you can get both from Toolstation, see p 260 of their current catalogue). Vent pipe down to the gravel. Radon barrier dpm laid over the sand and taped to vent pipe.Then concrete in place of flags. Around edges just take out a couple of inches of earth if you're worried about the foundations. Bring radon barrier right out to the walls and lay concrete over Ensure seal to wall is as good as you can make it.
They may have been installed to deal with a real problem or to the standards required to deal with a really serious problem.
You certainly wouldn't want to use it. Tanking is almost always best done outside if possible. Where radon's a potential issue, it's all the more relevant because if one can provide escape routes for the gas before it ever gets into the house, it's a whole lot better. If you can waterproof the outside at the same time, so much the better.
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