Radon and garage conversion

Susie2017

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A relative is considering converting half of their double garage to a playroom/study for their kids. It was built in 2006 but doesn't appear to have a radon barrier in the foundations. A black membrane is present presumably damp proof course. He is wondering about retrofitting measures for radon given that the kids will be using it a lot. Is the best approach to fit a sump or paint a sealant on the concrete floors and walls. Anyone been down this route ? Any idea of costs ?
 

Susie2017

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No not in the garage. Hes about to commence internal works plasterboard etc. Test would delay renovations by several months so hes anxious to proceed without the test now and do remedial works first.
 

Susie2017

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Anyone know how to approach this issue. Works due to get underway to convert garage in the coming weeks.
 

Monbretia

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I got a sump fitted many years ago to my house, possibly up to 20yrs ago at this stage, I can't remember but it cost me about 3k at the time.

I watched the guy do it and to be honest it was never worth the money from the point of view of what went into the job, I would research a sump system and buy the stuff himself, I definitely don't think a specialist type company is needed like I got, a plumber did it in my local doctor's surgery as I noticed it and asked the doc about it years ago, cost a fraction of what mine cost. I was sorry afterwards I hadn't researched it better and bought the fan myself which is the only working part and they are not expensive. Rest of the work is not rocket science either.
 

Susie2017

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The walls are concrete block and floor is cement and intact. Walls will be lined with insulated plasterboard. He doesn't do DIY but definitely doesn't want to pay 3k either. The heat exchanger looks good. Any idea of price ? Is it difficult to install could a carpenter do it. Is it as simple as a vent to the room and one outside and an electric connection ?
 

Monbretia

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I had the vent system first but didn't bring down the levels, same company and they said they try that first and allow cost of that against sump if necessary, anyway not what the issue was but the noise of the vent fan or whatever it was drove me mad! Now I'm sure kids wouldn't care but I could hear it continually and found it very irritating, just something else to consider but maybe systems have improved at this stage! It was unit of some sort in the attic connected by tubes to the vents, like the things you see from kitchen fans.
 

Susie2017

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Ok. Will keep that in mind. Also there would be continual electric running costs unless you only turn it on when using the room ?. Not ideal. But I do like the idea of constant fresh air. Any risks with digging under the foundations of the garage to create a sump ? Could the floor collapse for instance?
 

Monbretia

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They only dug quite a small hole outside my house and in underneath, not enough to make anything collapse, the hole doesn't go in far at all and I think it's filled with stones anyway. The outside fan I have now runs continually 24/7, everyone including my electrician brother says it's very cheap to run but I have higher than normal electricity bills so don't know who to believe on that one! They have to run continually to the best of my knowledge. Is the house in a high radon area or have they had a test done? I know the best tests are the ones that take a few months but there are more instant tests there as I know the company I used did one, obviously it's only a moment in time but it's an indication at least.

To be honest unless there is a high risk of radon in the area I'm not sure I would bothering doing anything especially for a space that no one is sleeping in so not in constant use.
 

Susie2017

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Ok. A test was done some years back on the adjacent house but it was within the acceptable levels. I assume as the house was built in 06 it would have a radon membrane but I am not certain on that. The garage doesn't appear to have one. They are anxious to prevent illness if possible and with a reasonable outlay.
 

Monbretia

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Then really testing first is the only way to find out if it's worth the expenditure. Check what the regulations were back in 06 for radon barriers, I am assuming the garage is a standalone one and not attached to house so might be different regs for that.

Research how to put in a sump, after watching it being done and unless the method has changed in recent years it was a very simple process and I'm sure some local tradespeople would be capable of it rather than having to hire a specialist company.
 

Micks'r

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Depending on the renovation works being done and the resultant air tightness but possibly a positive input ventilation system (PIV) might both ventilate the space and create a slight positive internal pressure thus reducing any radon gas ingress.
Btw, I'm generally against PIV systems in houses but this situation could be a good exception.
 
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Monbretia

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That's actually what I had first, it pushed air in rather than venting it out.

That made no mess fitting it into my existing house so maybe they could go ahead with renovations and stick in the radon measuring device for the 3 months and see how it is, can always be fitted then if necessary.
 

Susie2017

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Sounds like a good suggestion. Garage is separate to the main house, but I gather that is irrelevant as radon barrier should be in the main house (not sure how to confirm). But in any case I gather adjacent dwellings can differ widely in their radon measurements. I assume they can also vary from minute to minute. Odd that you cant measure it in real time like a CO detector. Thank you to all for advice.
 
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