basement walls: moisture control

[Bruce Seidner]

I am building a new miter saw bench on a block wall and earth on the other side. I have had shelves there for 15 years and the blue Tapcon screws are a bit rusted and there is mineral deposit on the brackets they hold. No serious water but more than the masonry sealer paint managed to prevent. The shelves are coming down to make room for the bench and some combination of shelves and cabinets above it.

I want to use a base of 3/4" plywood to cover the wall that will serve as a barrier and serve as the support for a nicer and visible 1/4" plywood and whatever else I fix to the wall.

I don't know anything about construction plywood products but the fellow at Home Depot thought that the Advantage subfloor 23/32 would be his first choice. This may be so but I thought I would check this out. This stuff is very different than the cabinet grade plywood I do know my way around and which will be covering the Advantage subfloor material. At $29 for a 4x8 it is not the cheapest of what I saw there, some OSB weighs in at $13, but it may be the best for this application. I dunno.

In any event I found that Tapcon makes a masonry screw in stainless steel and I have those now at the ready.

Advice is invited and welcome.

Bruce

[Bill ThompsonNM]

At my last house I used epoxy basement paint on my basement walls to solve a moisture problem. It worked very well. I would suggest something like that before any plywood or you are liable to end up with a mold problem when you cover the wall.

[Bruce Seidner]

I thought this wood working hobby was supposed to keep me sharp as I age?

I did buy a can of basement block sealing paint. I was hoping to do some plywood surgery and a bench tuck in addition to give the wall a younger and more functional look.

What base would you use before you applied a nice 1/4" cabinet grade plywood for the surface that showed?

[Lee Koepke]

Attach 2x4 PT furring to the wall, then attach the plywood to that. The air gap will keep the air flow and reduce the chance of mold growth. The epoxy paint will help with the moisture as well.

[John Coloccia]

My first choice would be to build a 1X3 "fake" wall several inches away from the block wall. That would nearly always be my first choice. In my case, that was impossible as it would have blocked the entrance to the shop. I had just enough room to do my second choice, and this is what I actually did:

1) high quality sealer on the wall (high quality = big $$$, but worth it). I used Sanitred. IMHO, Drylock and similar products are practically worthless, especially if you're going to cover the wall so reapplication is impossible. Sanitred is a two part catalyzed rubber product. Apparently it can even be used to stop running water by injecting into cracks. Good stuff. You have to follow the instructions to the T. Works super on floors too. Wish I'd spent the time and extra $$ to do that before moving all the equipment in.

2) Dow wallmate insulation, or similar, on the walls. Again, not cheap, but effective. It's designed to be attached with, and has channels for, 1X3 furing strips.

I stressed over this for weeks before actually doing it, asking everyone I could, including my inspector (who presumably was familiar with botched jobs and water damage), and these two methods were sort of the general consensus on what actually works long term.

Sticking bare wood to foundation is almost never a good idea. Even if it's perfectly sealed, the cool wall will naturally want to condense any moisture in the air.

[Bruce Seidner]

I just saw the promo for Dow Wallmate and it is a very clever hack. I just have one 15' wall I am concerned about so cost will (I hope) not be a big factor.

This was a huge help.