Exposed brick sealing?

after reading bkgeorgian’s comment and op’s post (again) i realize what i am saying may be misconstrued. the suggestions i make have nothing to do with moisture sealing (sure thompsons can be used on the OUTSIDE of brick to keep moisture from coming in from the outside and i am not sure that would work anyway; people seal the outside of below grade brick with other unattractive things like flashing cement) but more to do with protecting the appearance of the brick as one might apply a clear coat to wood. i suspect that is what the op was looking for but to bkgeorgian’s point, if you try to apply something to brick on the inside (such as water based poly which i would still research) it might very well hide the issue for a little while and erupt as a full blown headache later (moisture coming through wood from the other side causes issues all the time).

of course they have product to water seal cellar walls from the inside. drylock or something but that will white wash the wall and you will lose the “brick” appearance.

if that is a front facing wall, the water can be coming in from the outside. in our house (which is a 1920’s queens house and may be constructed different) water can slip in under the roof where the roof hangs over the rear facia (i sealed that gap by running fiberglass tape and flashing cement over the roof and into the gutter). it then runs down the inside of the rear wall of the house – doing nothing until it hits something on the first floor and appears in the kitchen. its bizarre. leaks can be bizarre. as bkgeorgian said, check the capstones (we should all check these, failing joints in the capstones lead to a lot of parapit rebuilds). some houses do not have capstones, but the roof bends over the top of the brick and is sealed to the one next door. in commercial buildings, we would have a leak appearing some place inside and would trace it back along structural elements to an origin hundreds of feet away. this can take time – so plan on watching the area for a while.

you might be able to seal the area between the ceiling and brick with crown molding for appearance. caulk would be a disaster in a place like that. i often thought of trying expandable foam in such a gap and letting it dry and cutting it off with a razor or plunge saw and then finishing it like one would finish a wall – with compound. i might have done something like that once but cannot recall but it sounds like it would work.

Before doing any form of moisture sealing, you may want to check your shared coping blocks atop your house. Sometimes the mortar there will degrade, or the blocks themselves will crack, roof material will pull away from the party wall, etc. Finding the source of the leak should be the utmost priority, sealing and cosmetic repair should only follow once it’s fixed.

and keep something in mind with brick: its not like wood where if we put something on we do not like, we can sand it off. once its on brick, its pretty much on it. during a period of unemployment one time i had to take a job sanding something off a massive brick wall in a commercial facility that was being converted into residences; it was not fun and it came with all sorts of health hazards (this is why i complain in some other posts about hiring people without worker protections – been there, done that; its ok when we are young but health does not last forever).

the thompsons will soak in and disappear with little affect on the surface. i just don’t know if that is what you are looking for.

if others do not come on here, keep reading.

i do not know why others have not come on here and said something. I reno’d an entire unit in the city in the 90’s and we never sealed the brick but the owner was discussing with me. his feeling was that if it is not sealed, it would keep breaking down and producing dust. this was almost pre internet so we could not check all this out and read like we can today – but he had either heard that or read it and we could not find the solution.

i know not what to do: do not put oil base poly on there. as it ages it will yellow and look like poop spread on the brick. i had seen it done long ago before all the other products had come along.

i am thinking that back in the 90’s we talked of using water base poly. that would not yellow and low lustre might not show a gloss. but also, brick will absorb product unevenly (like wood does, i am a woodworker; brick probably absorbs more though and more evenly that wood, but it will not be perfect) and unless you put a lot on you might see some “build” in some places and none in others – “splotchy”.

do not attempt to use water based poly on my suggestion above. go read about it and see what others say. there are other things you can put on brick, thompson’s water seal (which will not keep water out from the outside but will help with the brick on the inside) but i am not sure that will have the effect you might want.

wait to see what others say or read. someone on here has done this they are just not on here now.