Sealing Brick

By Tim Carter
©1993-2009 Tim Carter

Summary: Sealing brick will remove the confusion the homeowner feels when they find a foundation or brick leak. Didn't they buy a weatherproof brick home? Where can these mysterious leaks be coming from? All of the mortar joints look tight. The brickwork appears sound. Is it the roof, a window, where...?

The Future

If you want to set up your son or daughter in a future business that is going to do quite well, I suggest you teach them how to remove the bottom eight courses of brick from a house without causing the brick above to collapse. They will also need some carpentry skills as they will be replacing the rim joist or band board that sits on top of the foundation. You see, these wood framing members and quite possibly joist ends and wall studs are going to be rotted. Years of penetrating moisture will have caused this damage. The sad thing is that all of this expensive work could have been avoided. If only the bricklayers and builders had done their homework and taken the necessary steps to collect and divert the incoming water.

Preventing Brick Leaks

Bricklaying is a true craft and art form. Like so many things in residential construction today, it is a dying craft. There are just a handful of masons who still strive to do quality work and want to do it right. You will find that the largest majority of these masons actually do commercial and institutional work.

Many residential masons - hundreds of whom work in southwest Ohio - do not have adequate training. They are young people who start to work for bricklayers who have not had any training themselves, or who do not stay abreast of new products or technology. The same thing may be true in your city or town. You may have bricklayers who are simply doing things wrong because they don't have a clue how to do them right!

You stop leaks in brick masonry by understanding that water does penetrate brick and mortar. You solve leaks by capturing the water and doing whatever is necessary to redirect it outside the brick wall. These methods are covered in greater detail later in this Bulletin.

Brick Sealers - What For?

I am amazed at how people think you have to seal masonry to preserve it. Fifty years ago there were no brick sealers! How have all those old brick buildings lasted? How did they survive before sealers? The point is that many of today's brick are much stronger than those that are 70 to 100 years old. Old brick sometimes didn't get fired as hot or as long as today's brick. There were inconsistencies in materials and quality standards. A good brick made today can easily last hundreds of years without a sealer.

The mortar many bricklayers use today is also different than that used 100 years ago. Today we use high strength mortars. They have considerably more cement in them than those from 100 years ago. The added cement helps to protect the mortar from weathering. As such, sealers aren't needed to protect the mortar.

The use of sealers has blossomed, I believe, because of the problems with leaks. The growth of the industry is also fueled by massive amounts of advertising. If a company can convince you that you have a problem and they have a solution, then a sale is a possibility.

A Finger in the Dike

So your bricks leak now. What do you do? A sealer - really, you want a water repellent - is maybe going to solve your problem. There is a possibility that the brickwork is so poor and the water entry paths so large that a water repellent just can't stop all of the water migration.

Remember that wind driven rain is your biggest culprit. The weight of the water driving against brick and mortar actually squeezes water through the brick like toothpaste through a tube. You have probably noticed this fact.

Some heavily advertised national brand products are film forming sealants. These are also rans as far as the Brick Industry Association is concerned. The best technology available involves special chemicals called silanes and siloxanes. These are cousins of the old standby silicone. Silicone is also a film forming sealant. It is not recommended for any masonry that can be subjected to freezing temperatures.

Many of the silane and siloxane sealers are environmentally friendly. They are water based and clear. They apply easily with a hand pump sprayer. I recommend that you follow the installation instructions to the letter. Some instructions are detailed and some water repellents may require two coats. Spend the time to read the label!



Comments:

SHERMAN LADNER
15 Dec 2007, 12:35
Iam a painter, Ihave a customer that has a patio that is brick. WE APPLIED MINWAX SPAR URETHANE FOR SEALER. WE ALLOWED THE SEALER TO DRY 8 HRS.EVERYONE INFORMED ME THIS WAS A GOOD THING AND PRODUCT TO USE. NOW, SOME OF THE BRICK LOOKS MILKY.CUSTOMER WANTED IT REMOVED, WHAT IS A GOOD PRODUCT I CAN USE IN PLACE OF THE
URETHANE for a sealer that is fast drying and a good sealer?
AsktheBuilder
15 Dec 2007, 14:24
Sherman,
AAAACCCCCKKKKKK! What a mistake. It needs to be stripped off and then leave it alone. Some sealers make brick slippery.
Tommy Coggins
28 Dec 2007, 12:54
We have leak inside fireplace. We had new roof/flashing put on and new cap on chimney. We have gas insert now. We can hear the drops of water hitting top of insert. If water coming thru brick, can you advise sealer that we can put on ourself? Or should we contact a mason or contractor?

Hope you can help!
AsktheBuilder
28 Dec 2007, 14:19
Tommy,
Read all of my Brick Veneer Water Leak columns. There are quite a few..... Also read all of my Chimney columns.
Melissa
28 Feb 2008, 18:58
Hi!

I need mortar advice but not for building. I recently made a sculpture using quikcrete and mortar. The sculpture is dry and solid, however, when I touch it, the surface is powdery and comes off onto my finger. Is there something nontoxic that I can use to seal the mortar? Also, this is for indoors only so it won't be subjected to weather. It's also very small so I don't need a whole gallon of concrete sealer which is a whopping $30 here in HI. Any suggestions, please?
AsktheBuilder
04 Mar 2008, 16:06
Melissa,
You could try clear water-based urethane.
robert b
06 Mar 2008, 08:01
I HAVE EFFORESCENSE FORMING ON THE BRICKS INSIDE MY BASEMENT.TO REMEDY THIS,I WAS GOING TO TUCKPOINT AND SEAL OUTSIDE BRICK WITH A PENETRATING SEALER.ON THE INSIDE,I WOULD LIKE TO CLEAN BRICK,APPLY HYDRAULIC CEMENT AND THEN PAINT WITH WATER PROOFING PAINT.DOES THIS SOUND LIKE A GOOD PLAN OF ATTACK?
AsktheBuilder
09 Mar 2008, 10:56
Robert,
No. Please go read ALL of my columns on:

Efflorescence

Be sure to spell it correctly when you type it into the search box at the top of this page.
Mel
26 Mar 2008, 18:11
I have a condo in New Orleans that was converted from a old warehouse. One of the walls is a brick wall. As you can imagine, during the summer it gets humid inside despite the a/c. Can I seal the brick on the inside of the condo to prevent some of this moisture from entering my condo? And if so what do I use??

Mel
AsktheBuilder
28 Mar 2008, 15:40
Mel,
It needs to be sealed on the outside. You can't let water soak into the brick. Read all of my Brick-Sealer columns. I talk all about the best ones.

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