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Community and Q&A

Efflorescence / spalling in brick basement

jonhaque | Posted in General Questions on


I think I have an efflorescence/spalling problem in my basement foundation walls. This will be a bit of a long post as I want to include any details that may be relevant.

I’m not sure of a few things about it:
A) How much of a problem it is (cosmetic or structural?)
B) If the paint on the basement walls is a contributor
C) What the source of the moisture is (although I have suspicions)

Photos posted here:

A bit of background:
The efflorescence is on two walls of the brick foundation wall in my basement. The efflorescence runs horizontally, with the worst parts in a band roughly a foot below ground level. The two walls that don’t have any problems are the northern wall, shared with my neighbor (it’s a semi detached house), and the Western wall, at the front of the house, where the front porch awning is, I assume, keeping the ground dry. The walls are mutli-wythe, with the exterior brick a textured red, and the interior bricks are solid and greyish. I don’t see any efflorescence on the outside of the building (although if it’s at the same height as inside then it would be underground).

The southern wall has an asphalt driveway between it and my neighbor, which comes right up to the brick. There are some cracks in the asphalt where it touches the wall, which I suspect of letting water in. Based on advice from another post here I will be ceiling those cracks with caulk. (

A) On the vast majority of the affected areas, it seems to be only the paint that is affected. At one point though, underneath the bubbling paint, there is a thin layer of the brick that felt crumbly and powdered off when I touched it. Underneath that was normal hard brick.

B) Would I have any problem at all if the walls were not painted? Can the paint be preventing the brick from drying properly or something?

C) Given that I don’t see any efflorescence on the wall that’s shared with the neighbor, or on the wall whose adjoining ground is protected by the front porch awning, I’m thinking the water must be coming from the rain and not capillary action. Does that sound right? One thing that puzzles me is that the basement is dry, no water seeping in even on very very rainy days.

Thanks very much,

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  1. GBA Editor
    Martin Holladay | | #1

    Here is a link to an article that describes what's going on in your basement: Efflorescence = Water Damage.

    What's happening is that water is evaporating from your damp bricks, leaving salts behind. The salts are damaging the bricks and mortar and paint. Even if your basement seems dry, water can still be evaporating inward from these brick walls.

    The traditional solution is to clean up the flaking materials and to cover the brickwork with a sacrificial layer of lime-based plaster. This will work for several years. Once the lime plaster starts to flake off, it will be time to clean up the mess and do the work again.

  2. Richard Beyer | | #2

    Here's another option when money matters justify a band-aid.

    Pressure wash the paint and flaking brick down to a more solid structure. Brush the brick with clean potable water to dampen the surface if it's allowed to dry before your next step. Skim coat with the smooth side of a steel trowel using TYPE S straight mortar (no sand). The mix should not be any thicker than peanut butter and not to thin as to not hold onto your trowel.
    If your application requires you to build up more than 3/16" at any given point you will need to add sand into the mix and then proceed without sand in the mix the following day. This will give you a smooth paintable finish.

    There are sealer's which can be applied called penetrating sealers. Some are guaranteed to penetrate up to 10" deep to block out water. There really are no guarantee's here if your budget can not swing managing water penetration from the exterior of the wall. However, many chemical manufacturer's will sell you a bridge if you do not read the fine print before purchasing. Not all sealers will work for your application.

    Another option is to install an interior perimeter drain and membrane system such as what this company offers if you have the budget.....
    These systems generally cost around $10G and they do all the work for you. Truth is they actually work well.

    Water management is your key to a long lasting retaining/foundation wall assembly and it also makes for better indoor air quality by eliminating spores and other contaminates from being forced through your home via the stack effect.

  3. jonhaque | | #3

    Thanks for the information.

    Martin, are sacrificial layers used on the inside as well? And would that preclude finishing the basement as I would need access to the walls for replacing the sacrificial layer? Or did you mean that I should do this on the outside of the wall above ground level for a few feet?

    Richard, is the idea that the sealer would penetrate the layer of mortar and the brick behind it as well?

    Thanks again

  4. Richard Beyer | | #4

    Jon if you do not manage the water migrating through the wall from it's source, finishing off the area by means of covering it with drywall, insulation and framing will only cause you grief and mold. Sealer's are band-aids and not cures for water movement. Again, manage the water from the source if your budget can withstand the impact.

  5. jonhaque | | #5

    Is it possible to use the asphalt driveway as a skirt as described here (pg 20):

    Since it comes right up to the wall, if I caulk or tar the seam between the wall and the asphalt, could that keep the soil dry enough (as the porch awning does on the front of the house)? Actually, is it more likely to be rain getting into the brick via the cracks between the asphalt and the wall that's the source of the water, or is it maybe water getting underneath the driveway somehow and then seeping in through the wall?

    If it sounds like I'm trying to think of anything that will let me do this without breaking the bank, it's because I am :)

  6. Richard Beyer | | #6

    Anything is possible and I do not fault you for seeking cheaper alternatives. Just understand your asking for advice all while providing bits and pieces of critical information.

    Q: "is it more likely to be rain getting into the brick via the cracks between the asphalt and the wall that's the source of the water, or is it maybe water getting underneath the driveway somehow and then seeping in through the wall?"

    A: Could be a combination of both.
    Sometimes high ground water could be the source more then rain driven water. Check your local water table. (elevation above sea level) Any river's, streams, ponds, wetlands or shallow wells nearby? Is your neighbor diverting their run off water over to your property? ie; Gutter's, watering plants, irrigation...etc.. Are you using irrigation and where are your gutters aimed? How far from the foundation? Do you see ponding water after a rain event?

    Based solely off of your previous post and the pictures you provided, I would like to think your problem stems from a sloping driveway leaning toward the house. If this is the case your only solution is to elevate the driveway so it slopes away from the home and then seal the brick chemically along with polyurethane caulk and backer rod at the meeting point. Or, take your chances and caulk only.

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