RadonSeal Plus Deep Penetrating Concrete Sealer for Basement Walls and Floors, Seals Concrete Against Water, Vapor and Radon Gas, (2.5 Gallons)

We bought RadonSeal Plus to help reduce radon levels in our home and ensure proper moisture levels in the concrete floor before installing LVP in our partially finished basement.We were surprised to get moisture test readings in the yellow since, as long as we've lived here, our sump pump has remained bone dry and we've had zero visible signs of water intrusion. After several months of monitoring humidity, dewpoint, etc, we concluded water vapor must be wicking up through the concrete.We decided to apply RadonSeal Plus to only the finished room first, since we need the new LVP installed in time for Christmas gatherings. RadonSeal was easy to apply, had little to no odor, and we could see it was being absorbed effectively into the concrete as it was applied.The instructions say it reaches full strength in 60 to 90 days. After 30 days we're pretty happy with the results so far. Our moisture readings have gone from yellow to green with our latest ASTM F1869 test reading 2.14. Our radon readings have gone from regular highs from 10 to 14 over the 3 months prior to the application, to now showing consistent levels between 4 to 6. This is after doing 1/3 of the basement (ONLY the finished area). After the holidays we'll seal the two unfinished areas of the basement and I'll be happy to report the final results here.

Seals well keeps the dust down and doesn't have a terrible smell even when used inside.

Easy to apply

I poured it out of the 2 gal container in various areas spreading with a broom on a 43 year old cement basement floor after hand scrubbing first 2 days before. It soaked in well and the reapply 40 min later also did well. Then I took a damp flat mop another 40 min later to get up any still wet areas. No smell at all. I won't know until I finish the total basement floor and test for radon if it helps. It did give a low sheen and I can see that the surface is sealed.

Product was delivered early when it was -40 degrees. I had a friend stop by my house to grab the package because I was worried about it freezing and I was out of town at the time. By the time they got the package they were pretty sure it was frozen solid but they didn't open the box. The next week when I returned I tried contacting RadonSeal customer service to see if I could still use the product since the SDS said to avoid freezing. It's been 3 weeks and I've heard nothing. In the meantime I needed to put carpet down so I went ahead and applied the product as advertised as it recommends 10 days to completely dry inside the concrete. Because it has no odor, no color, no reaction to the concrete - hard to say anything about whether it is a good product or not. I followed all instructions and had no residual white powder - but who's to say if that's because the product was completely ruined by freezing? I was sealing for radon (not water or effluence) which is varying between 2.5-8 pCi/L. After sealing I epoxy filled some 1/8-1/4' cracks in the slab. I'll keep monitoring the radon levels and see if they go down at all. I'm installing a sub slab depressurization system soon but I was hoping this would help mitigate the radon in the meantime. I may never know whether I was taken or not.

We're downsizing to a very small house and need to make use of our 50 y.o. concrete foundation basement since we will work a lot of time there. Existing under slab Radon vent system was borderline ineffective, and we have been continuously monitoring Radon levels. When I applied Radon Seal to the north half of the basement, Radon levels dropped noticeably. I've now completed the entire basement, and I will update this review after I've seen a few weeks of Radon levels on my monitor.

I washed the wall with etching acid to clear any efflorescence, wait for the wall to completely dry, then wire brush the wall and vacuum the wall. I misted the wall and spray the product. After 2 times of applying the product, I still see a lot of efflorescence in one spot. This spot has 1/4 inch of crystalline efflorescence before, and it's the same amount after sealing. I washed and brushed the spot again, and applied 2 more times. It's still there. I did a quick brush and wash, and applied Rapid Set Waterproofing Mortar, and it finally get rid of the efflorescence. That make me question if the sealer did anything at all.

It sprayed on perfectly. Two coats and I am very pleased with the results!