Metro Detroit’s Masonry Q&A Hub

A lot of the mortar between the bricks on my house next to my driveway is sandy and falling out so much that I can put my finger in there. Why is that happening?

Answer

One of the reasons this happens is because when the house was built, the original mortar may have been mixed poorly and too much lime was added and not enough cement, so weather slowly dissolves it.

Another reason this could be happening is because your driveway may be slightly pitched toward your house instead of away from it. If that’s the case, that part of the wall is taking extra abuse from rain, snow buildup, and repeated freeze–thaw cycles that drain toward your house and not away from it.

Salting the driveway in the winter also can make it worse by pulling moisture into the joints and crystallizing as it dries, which weakens the mortar and makes it sandy enough that you can rub your finger across it and eventually stick your finger in where mortar used to be.

Without physically seeing it, I would think tuckpointing should take care of the problem.

If ignored, eventually it will lead to brick replacement instead of tuckpointing.

Once the weather gets a little better, you should get that fixed while you’re still in the cheaper repair window. Being proactive could save you a fair amount of money down the road.

I recently had some tuckpointing done & I'm not sure it was done right. Is there a certain depth the mortar should be ground out or is just skimming the surface sufficient?

Answer

A good rule of thumb is to grind out the mortar joints about 1 inch or more. Just skimming the surface doesn’t fix the bad mortar joints. Barely skimming the surface of a mortar joint with a grinder and applying a tiny bit of mortar over it won’t hold, especially in colder climates like Bloomfield Hills due to temperature shifts. After one winter, the mortar will begin to flake off and you will have potentially spent a few thousand dollars for nothing. Grinding the mortar joints an inch deep or more ensures it’s deep enough for the mortar to stay securely in place and will last for many years to come, making your investment in tuckpointing your home well worth it.

Now the “elephant in the room”… whether the mortar was just barely skimmed or ground out an inch deep, once the work is complete they both look the same on the surface. Without knowing what’s going on behind the new mortar, even a professional can’t tell how deep the mortar was ground out, let alone a homeowner. You’ll have an idea what was done after a winter because poor tuckpointing will begin to flake off, but by that time the damage is done.

Point being… when you hire someone to perform tuckpointing on your home, get a clear understanding of their process. After you get an understanding, ask yourself if you trust them to do it properly. Otherwise, your only other option would be to supervise whoever is doing the tuckpointing so you can witness for yourself if they’re grinding the mortar out deep enough.