Sealing basement walls may be a mistake?

[Big John MacLean]

Good day,

I am in the process of waterproofing the basement in a house built in the

1920's. I'd like to know if Xypex Concentrate will worrk, given the details of the concrete;

- having routed out a few cracks the concrete (mortar?) appears to be quite sandy in composition, and brown in colour where water has seeped through over the years, otherwise the interior surface of the basement walls is grey.

- there are stones in the wall ranging from pebbles to football sized rocks, at least one! evident where the smooth surfaced concrete has fallen away by an inch' depth, revelaing this larger rock.

- efflorescence has appeared in a couple problem areas

My question is whether Xypex requires (and bear with my lack of knowledge here) lime to work, as I'm thinking this old concrete is a long ways off Portland cement.

This part of the country is fairly dry therefore not much hydrostatic pressure exists outside the wall - the water table is certainly below the basement floor. Still, I have read the odd report where sealing an old wall will allow hydrostatic pressure to build up to the point where the wall will cave in. Is this true? Is it necessary to allow an old wall to 'breathe' moisture?

Any advice would be well received, thanks in advance,

JM

[Kyle Boatright]

I'd seal the walls if I had dampness coming through the walls. If I had visible water coming through the wall, I'd fix the drainage problem, then seal the walls. I can't see where using a sealing product would eventually lead to a wall collapse. The amount of water that can wick through concrete or mortar is relatively small, and wouldn't be enough to relieve the hydrostatic pressure necessary to bring down a wall.

KB