centerfield9

I have poured concrete basement walls and floor and looking to install a radon mitigation system. The basement is dry. To make the system more efficient, I want to coat the walls and floor with a sealant. Does anyone have a good sealant to recommend?

centerfield9

anyone?

itsreallyconc

its unusual to hear of a bsmt w/dangerous radon levels but not unknown, either,,, after the radon test, if you've done a moisture test to be CERTAIN its dry, you can use a cementitious wall coating such as avail at the apron stores,,, matter of fact, this is probably the 1ST time i've EVER recommended it seal the cove jnt w/acylic-latex caulk,,, wait 30d to seal the conc surrounding your exhaust as the conc needs time to cure,,, if you think the floor needs sealing, apron stores have stuff, too.

ccarlisle

I bought a pail of RadonSeal a few years ago and had it kicking around the garage for so long that I just brought it to the Hazmat guys a few weeks ago - would have gladly given it to you...there was about 2 gallons left and it might not have done - but still.

I know silicate concrete sealers and I bought this product for a sealing job where the circumstances were similar to yours but it was more for hardening and waterproofing than radon mitigation; and to be honest, I don't know how effective it - or any product - would be against minute amounts of radon gas. Even if you are sitting on a radon pocket, I'm not convinced an interior product would work given the porosity of concrete and the agressive nature of gasses trying to get into a space. Seems you'd need to live in a bubble...

I think I paid $170 for a 5gallon pail of a silicate I used to sell industrially for $30. Either sodium or potassium silicate can't remember offhand without looking it up but it was produced locally by PPG, a glass-manufacturing plant. To me it would work as a waterproofer but again have my doubts about radon mitigation.

Are you sure you have radon at levels that are dangerous and not just swallowing the sinker along with the hook of "Dangerous Radon"?

centerfield9

I did a short-term and long-term test and both were above the EPA recommended level of 4 pCi/L. Long-term came in at 14 pCi/L. I know a sealer alone isn't enough, but it would be nice to have the suction system work as efficiently as possible.

ccarlisle

"I did a short-term and long-term test..."

Interesting...you did it yourself?? or had someone do it? and what agency/company did that? and what's along-term test?

I'm just interested that's all.... and where are you located?

centerfield9

I bought a short-term test kit from Home Depot, put the detector in the basement for 30 days, then sent it in to be read. It came back a little high (7, I think). To confirm the reading, it was recommended that I do a long-term test, so I got the LT test kit from the Vermont Dept of Health, left the detector in the basement for a year, then sent it in to be read. The LT results came back at 14.4.

It's easy. You just have to log the start dates and remember to stop the test (by putting the detector in a foil bag).

itsreallyconc

i think i'd install an air exchanger 1st when comparing the cost of a radon-evac system,,, carlisle, does that paint on **** really work ? ? ? what about silicone siloxane realizing radon particles're smaller than wtr ? ? ?

norwich '64

Maintenance 6

It's not all that unusual around here to see levels much higher than those posted. Your levels aren't that high compared to some I've seen. The law in Pennsylvania is that once you test and have data in hand, you are obligated to disclose it to any future buyer. Most people I know don't test just for that reason. Most likely place for infiltration is between the floor slab and walls. I'd start by sealing that joint. The problem, as I see it, will be that any coating that is effective against radon will also trap moisture. Vapor pressure will likely lift the coating. A breathable coating will really defeat your purpose.

ccarlisle

itsreallyconc:

Oh yeah, silicates work in concrete alright - as well as in a couple of dozen other industries. In concrete, silicates act to harden and waterproof the surface by interacting chemically with the free calcium alkalinity, essentially taking the alkalinity out of action and creating a hard binder: calcium silicate. PQ Corp makes all the silicates - just ask them about the millions of pounds they produce (pqcorp.com) every year.

So how do they compare to silicone technology that does the same thing? Well, silicones represent inert monomer compounds that polymerize into another inert compound that provides such a physio-chemical barrier that water can't penetrate it. The 'car wax' effect...but as effective as they are at doing that, it is still a physical+chemical "barrier" whereas the silicates are uniquely chemical - and therefore it could be argued that silicates operate on an atomic level i.e at the smallest level we know of.

Personally, I put my money on chemical reactions from chemical products...i.e. they work almost no matter what...put two simple, acid-meets-base compounds together in the same room - and the reaction happens. Not so for all compounds however, as certain other tangibles have to be right for them to react.

But I wouldn't bet against silanes doing the job too. But silicates have a longer history in far more fields.

ccarlisle

Just to prevent people getting the wrong idea, I maintain that, no matter how effective silicates or silicones are in surface treatment of concrete, I just don't see how interior sealants would affect radon levels in a home. They aren't meant to reduce gas or vapour permeability- that's a whole different question. I used RadonSeal for waterproofing which is a known result of silicates on concrete that still has residual alkalinity in it.

Nothing much you can do about radon except try to mitigate the effects it has upon the occupants in a home; so try to reduce the levels once it's there. The OP in Vermont reports a 4 pCi/L level - which is easily reached in parts of that state, as it is up here north of the border - but at the same time is a level that EPA recommends acting upon. So ventilation is called for...but personally, and before putting in $2500 into a fan system, I'd double check my test kit, and/or have a pro confirm those levels over a long period of time, including a heating season.