To Drylok or not to Drylok - DIY Chatroom

68tele · 11-01-2009, 04:23 PM

I am preparing to re-paint my basement, and have been planning to use Drylok in areas of the basement that are prone to seeping. I don't get flooding or serious water in the basement, but one wall in particular will get wet and seep after a hard rain.

When I tell people I'm planning to use Drylok, there seems to be two camps: one who thinks it's a good idea, and another who thinks that Drylok'ing the inside of the wall will just trap the water in the cinder block and cause more harm than good in the long run. Those folks would prefer to let the water come through the block where it can be dried out with fans and a dehumidifier.

I see merits in both, but then again none of these people actually have any experience with Drylok or experience to back up their position. There seems to be a lot of expertise on this forum, what are your thoughts on the matter?

chrisn · 11-01-2009, 07:50 PM

I would think that keeping the water out would hold priority.The walls must be completly free of existing paint to work properly.

Matthewt1970 · 11-01-2009, 10:11 PM

Yes. You mention "repainting". Drylok does not work over existing paint.

ccarlisle · 11-02-2009, 08:36 AM

I think a passive approach is asking for more trouble; if you dehumidify the inside in order to counteract water coming in from the outside, you create an imbalance in humidity levels causing mnore humidty to enter inside to fill the void; add to this the fact that cold goes to warm and you get an immediate channel for water in keep coming in. Plus, that process will never dry out the blocks entirely, just the air around it...

I think you need some sort of barrier; now an ideal barrier would be three coats of elactomeric selaant on top of an EPDM membrane stuck to the outside of your entire foundation all around the house but not many of us have money trees in the back yard...so failing that, Drylok may work best. 100sqft per gallon, two coats and according to them resists what may be more hydrostatic pressure than you seem to have.

However, you must also try to mitigate the problem in the first place by trying to see where the water is coming from and spending as much effort on that. As others have pointed out, a previously painted surface may interfere with Drylok's ability to function...so there's a ? there too.

68tele · 11-02-2009, 09:40 AM

It is a re-paint, but I'm planning on stripping the existing paint first so I can get back to the bare block. I wish there was more I could do on the prevention side for the water. The offending wall is covered up by my deck on the outside, which limits my options in terms of grading etc, and I've already extended the downspouts 15-20 feet from the house. Sounds like strip & Drylok is the way to go...

Thanks