# Exterior Brick Waterproofing Sealant



## billhead1 (Jun 23, 2012)

I had never heard of applying a waterproofing compound to exterior brick to prevent cracking from moisture intrusion during freezing conditions, but a contractor proposed and applied it to a neighbor's house. All exterior brick is located above the foundation curb, above grade. Is this a recommended practice? What is the maximum recommended pressure for pressure washing to avoid damaging bricks/mortar? According to Home Depot's Buying Guide for Waterproofers, "Waterproofers stop the flow of water through concrete while sealers only repel water. However, sealers do repel water and allow water vapor to move through the material. Apply these products to brick, concrete, block, stucco or other masonry material."


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## BridgeMan (Jun 26, 2012)

A great source of revenue for the manufacturers, suppliers and installers, but I question the need for doing so.  Millions of brick structures have never been sealed with anything, and are still performing reasonably well in all kinds of weather conditions.


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## oldognewtrick (Jun 26, 2012)

Bridgeman, I see a lot of issues with water migration through mortar, especially at chimney areas. When you can run your finger along a mortar joint and it looks like your running your finger through a sand box, theres usually an issue with water intrusion.


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## asbestos (Jun 26, 2012)

We have a brick house (well mostly brick anyway) it's from the 1950's and I have put some sealant on it, a penetrating sealant. I am not so worried about the bricks as I don't want to much moisture soaking in and gettin to the wood underneath. The tarpaper  they put on is not in the best shape. So I figure the less water getting to it the better.


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## BridgeMan (Jun 26, 2012)

oldog/newtrick said:


> Bridgeman, I see a lot of issues with water migration through mortar, especially at chimney areas. When you can run your finger along a mortar joint and it looks like your running your finger through a sand box, theres usually an issue with water intrusion.



I totally agree.  I've seen lots of improperly installed bricks, incorrect flashing, wrong type of mortar, too wet, and often improperly cured, performed by people in the trades who have no business still being there.

That being said, I stand by my original statements.  And qualified with my opinion that the best brick sealant in the world will not correct an initial lousy installation.   May buy some time, but only puts off the inevitable.


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## babs322 (Oct 14, 2012)

My chimney sweeper is recommending waterproofer for the outside of my "reused" brick fireplace chimney. I am hearing very conflicting reports about sealing brick. Any comments would be appreciated.


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## BridgeMan (Oct 15, 2012)

Using a sealer that can breathe should work, if anyone wants to spend the time and money to do it.  

I'd guess far more than half the brick chimneys in the world are not sealed.  Keep in mind it's a guess, and no, I don't have any facts to back that statement up.


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## nealtw (Oct 15, 2012)

Weeping holes at the bottom of a wall are there to remove any water that gets behind the brick. If water is running down the back of the brick it will be sucked into the brick in warm weather, a non-breathing sealer will prevent that moisture from getting out.


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## pgooose (Feb 1, 2013)

Are there different types of brick sealer and how do you choose?


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## BridgeMan (Feb 1, 2013)

Simple internet search will pull up the names of various products and manufacturers.  Then just wade through all of their respective product descriptions for the one that best suits your needs.  Larger outfits will have a free tech number to call if you have specific questions about something.


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## ccober (Sep 25, 2013)

It depends on the type of brick. I have clay bricks, and the two sides of my house don't have much overhang. As a result, the sides of the house get wet a lot, and when clay bricks get wet and then the water freezes, they get "spalling". Progressively larger pieces of the brick flake off -- every spring I have flakes of brick on my driveway, and some bricks have lost as much as an inch of their surface.

I'm replacing about a dozen bricks on one side of the house right now, and when it's done I'm definitely applying a sealer to the two side walls that get wet.


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## mudmixer (Sep 25, 2013)

Unfortunately some brick are not classified as being durable for severe conditions and will spall when saturated (or nearly so) and freeze.

Freezing causes interior pressure that must be released or the material can spall. A proper sealer for bricks does not allow the liquid form of water through, but will allow the vapor form of moisture through. A good/perfect 100% waterproofer can cause spalling because water can always enter a chimney either from above, through a bad joint of from condensation and temperature differentials.

There are many acceptible products, but usually not from a big box store with a handout written by salesman or a cute little girl in the main office.

Dick


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## BridgeMan (Sep 27, 2013)

And don't forget, Dick, that sometimes that "cute little girl in the main office" can be ugly as sin, and weigh 350 lb.

I shouldn't talk, as my beer belly is protruding to the point that my belt buckle is almost invisible.  Bought my first pair of suspenders a while back.  And I haven't won a single beauty contest since joining life on this planet almost 70 years ago, either.


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