Q&A / 

Brick Leaks

Brick Leaks

Can you see what I see? There's no visible flashing behind the brick, I don't see a water membrane covering the wood framing behind the brick! What's more, do you see any weep holes? I sure don't. © 2017 Tim Carter

Brick Leaks TIPS

DEAR TIM: Every time a wind-blown rain saturates our brick veneer home water streams into our home. I've noticed that the wood floors in our living room are warping as well.

The brick and mortar appear fine. What's causing the leaks? How should the brick have been installed? What, if anything, can be done to stop the water penetration? Brenda F., Brockton, MA

DEAR BRENDA: I hate to tell you this, but you've got some very serious problems. If they're not corrected, serious structural failure will be in your future.

I'm quite confident that if I did a post mortem examination of your brick walls, I would find serious workmanship errors.

CLICK HERE to get FREE & FAST BIDS from local painters that can spray on special silane-siloxane water repellents.

Brick Leaks Lots

Virtually every brick wall will allow water to penetrate. The water has three possible paths. It can enter directly through the brick, the mortar, and/or the contact zone between the brick and mortar.

Vertical Head Joints Worst

The primary path of water into brick walls is the contact zone between brick and mortar and mortar joints that are not filled completely.

Your wall leaks, I'll wager, are most likely originating at the vertical joints between many of the brick. Bricklayers call these head joints.

Because of the way bricklayers butter the one side of a brick, these head joints are susceptible to leaking. One side of every brick has got this weakness.

The bricklayers often cut away the bed, or horizontal, joint mortar as they set the brick to the string line. This mortar has already lost some of its valuable moisture from laying on the previous course.

The bricklayer then takes this scraped mortar and puts it on the end of the brick he just laid. He does it at an angle and only a small amount of the mortar contacts the side face of the brick. The mortar makes a less-than-desirable bond with the brick.

Mythical Mortar

The quality, type, and moisture content of the mortar is a critical factor in preventing brick veneer wall leaks. The mortar for a brick veneer house needs to have a high lime and low cement content.

Do you recall the great line written by J.R.R. Tolkien in his book The Fellowship of the Ring? It was said by the character Galadriel, 

And some things that should not have been forgotten were lost. History became legend. Legend became myth. And for two and a half thousand years, the ring passed out of all knowledge.

This applies directly to hydrated lime. It's rapidly becoming a myth in the building industry. Older brick buildings, those built prior to 1900, almost exclusively used hydrated lime mixed with sand instead of Portland cement.

hydrated lime

This is excellent hydrated lime. It's a fine white powder and it's going to look great on your home. CLICK THE IMAGE TO ORDER SOME RIGHT NOW.

The lime in the mortar, through the years, can actually heal tiny cracks that might develop between the brick and mortar. Hydrated lime is an amazing material to mix with sand to make mortar.

Mortar that is too wet or has too much cement can shrink as it dries. This shrinkage can produce tiny cracks that allow water to easily penetrate the wall.

Solid Masonry Construction

Older brick houses usually were never a brick veneer. Often the brick walls were two, three and sometimes four brick thick bonded with lower-strength, high-lime content mortar.

The inner courses of brick were very soft and absorbent. Rainwater would collect within the wall and then be released to the atmosphere once the storm passed.

Brick Veneer - Hidden Waterfalls

Modern single-thickness brick veneer walls deliver the wind-driven rain within a matter of minutes to the wood frame system just on the other side of the brick. This water needs to be collected and transported immediately to the exterior of the house.

CLICK HERE to get FREE & FAST BIDS from local painters that can spray on special silane-siloxane water repellents.


This is accomplished by installing flashing materials at the base of the brick wall, above all doors and windows, and below all window and door sills. The flashing must be continuous and needs to be made from a material that allows joints to be permanently sealed.

High-quality brick-veneer flashings can be made from modified asphalt and high-quality polyethylene and copper/asphalt combinations. Do not use the low quality "garbage bag" or PVC type plastic. It's useless.

Cover All Wood

The exterior of your wood-framed walls should also have been covered with a water-resistant membrane. Overlapping horizontal pieces of time tested tar paper will work.

However, there are many air and moisture barriers that will do as good a job or better at preventing the leaking water from contacting your wood framing. These moisture barriers must be installed so they lap over the wall flashings.

Weep Holes

Weep holes at the bottom of all walls and at the top of windows and doors need to be no less than 4 feet on center. Two-feet on center is preferable.

The cavity behind the lowest courses of brick needs to be free and clear of mortar droppings. This allows leaking water to easily escape through the weep holes.

Mortar Catch

An ingenious saw-toothed plastic netting can accomplish this task easily. It fits behind the first few courses of brick.

Silane-Siloxane Water Repellents

Your leaks may be able to be stopped with the application of high-quality water repellents. These materials contain special chemicals called silanes, siloxanes, or a blend of the two. CLICK HERE to get a fantastic one that will do a great job.

silane - siloxane water repellent

This is a magnificent silane - siloxane water repellent that soaks into concrete. CLICK THIS IMAGE NOW TO ORDER IT.

Examine your brick walls. Look for tiny hairline cracks in the vertical joints. Remove and install new mortar if you find obvious water entry points. After the joints dry, apply the water repellents according to the manufacturer's instructions.

Leaf Blower Secret

A second application may be necessary and it usually needs to be applied within minutes of the first coat. It helps to use a backpack leaf blower operated by a helper while you apply the water repellents.

The blower drives the repellent deep into the brick and mortar. The blower blasts the wall immediately after you apply the liquid.

If this does not solve your leak problem, I'm afraid that your only solution might be to re-install the brickwork properly.

CLICK HERE to get FREE & FAST BIDS from local painters that can spray on special silane-siloxane water repellents.

Column 198


31 Responses to Brick Leaks

  1. I would like to know the names of brick repellents for crumbling red brick
    If I use the repellents on the outside wall; how do I apply to already paints walls on the inside walls. Trying to drill out holes on the inside building to attach false wall but find the bricks are crumbling when trying to drill through.
    Any suggestion . Thanks Rita

  2. Tim,

    I have leaks coming into my brick in my attic. There is too much mortar on the back of the brick and very little tar paper. The water is going through the brick over the large deposits of mortar and into my house. I have a guy who wants to apply some kind of fiberglass mortar (or something ) to the inside (which is my attic) and then put up tyvec or tar paper. He advised that after this he would repoint the walls on the outside. What are your thoughts?

    • Tony, your question requires lots of typing, plus I have some questions for you so I can give you the correct answer(s). I only do pithy answers here in the comment section. If you want to protect the investment you have in your house and not waste time or money *hoping* you make the right decision, you should talk to me on the phone for just 15 minutes. It'll be the best investment you've ever made in your home!

  3. I have a garage with brick veneer that leaks into the garage from under the sill plate. The brick is below grade level which I think is the problem. Regrading really isnt an option. Is there a way to pull the dirt away where the brick meets the footing, place a waterproofing material at the seam then back fill? If so can you recommend a waterproofing material?

  4. Brick leaking can be resolved by wrap the house? Which material is the best choice ,of course ,not very expensive.

  5. I have a 1980s detached brick built house. In 2011 I had cavity wall insulation installed,since the New Year when we have experience
    wind driven rain the south facing wall has allowed water to leak into the conservatory over the back door and window lintel in several places through the brickwork. The same appears to be happening over the exposed windows. Any advice would be appreciated.

  6. Our house is all brick built in 1985

    When it rains I have a 5 X 9 foot section where all exterior bricks are wet . This section of brick is between two sliding doors leading out to a concrete patio in our basement. A couple of years ago we replaced the carpet in that basement and I did not see any water damage on the concrete floor.

    Over the past year, the section of brick that becomes wet is increasing. It is not getting any wider and stops right before it reaches either of the sliding doors. But, it is getting higher and starting to reach up to the first floor brick in that area. We have a wooden porch coming out from the brick wall above this area but I have always kept it heavily caulked where the porch attaches into the brick wall.

    The brick and mortar looks to be in pretty good shape.

    What do you think? Do you think a water repellant might fix this?

  7. We installed 80 brick mailboxes in our neighborhood. There is door, but no mailbox insert (just concrete). We get wet mail from condensation.

    THe opening is 7 by 7 inch and I wondering what is best option to tackle this. Tried to find 7 by 7 mailbox insert, but can't find. thoughts to eliminate wet mail due to moisture in brick unit?

  8. Hi ive just taken my skirtin.boards of and noticed on my main back wall were the wall meets the floor there are wet patches and i dont no what to do

  9. I live in a home built around 1890. When there is substantial rain or snow melt, I can actually see the areas where water is coming in around the bricks in our basement "walls."

  10. Just bought a house with brick veneer. The 6 inch thick concrete driveway have been cast against the wall covering well above any weep holes. Any suggestion how to best fix this?

  11. My back yard has a red brick wall that is firmly on my land. Sometime in the past (before I bought the house) my neighbor built a garage/ in-laws apartment using the brick wall as one of the walls of the house. Now they are getting water inside their in-law house where a 30foot tree has grown close to the wall. Needless to say they want to cut down the tree to fix the wall. My question is can they fix the wall from their side by breaking loose the two layers of brick from their side and then re-doing to mortar work for the impacted area's? Or is there another solution that can be done without cutting down the tree.

    Thank you

  12. I am looking to buy a house that has a concrete patio above the garage. The patio has brick pavers. During a heavy rain, water leaks through the patio into the garage. Is this going to be a costly repair?

  13. Thanks, Tim. I have done a lot if searching about the leaks from the top of my windows (brick exterior) with no good explanations until I stumbled on yours. Thanks.

  14. Hello, I have leaks in the mortar joints surrounding exterior lights that were installed. The interior of the wall has been foam insulated so I can't tell how large the compromised area is without ripping out the foam. Any way to test this from the outside? Best way to fix?

  15. Hi Tim- we have brick steps at the front of our house. Certain bricks are always wet even on days when it isn't raining or hasn't rained in a while. Is it possible that there is a leak somewhere or is it normal?

  16. I have a newly built extension and I notice that a lot of the bricks have hairline cracks on the face of them Im worried about water ingress and future frost damage. I am concerned that the bricks are substandard and possibly have not been fired properly how can find out ?pictures can be sent

  17. Please excuse my ignorance but I just inherited this house built somewhere in the neighborhood of 1950. The builder or landscaper decided to have the dirt surrounding the house go up about 2 1/2 feet on the brick all the way around the house and taper down into the yard at an angle. Now after a day or 2 of heavy rain we have to vacuum water from every room in the house for several hours depending on the rain amount. The house was recently hit directly by Hurricane Harvey and I now have all of the drywall out and the exposed brick is visible. It looks like there was a black material between the studs and the brick but the majority of it has also fallen apart. Is there anything we do to fix this problem before we reinstall the drywall ? Any help would be greatly appreciated. Thanks

  18. I have a brick work dome(like a truncated prism) for a temple in Houston area. The brick dome(plastered & Indian art work is done by cement figures on the outside). The (closed at top)dome about 20 ft higher than the roof slab)penetrates through a concrete roof slab. The concrete roof slab was waterproofed by a roof professional with flashing on the brick dome. Still we can see the leaks in heavy rains. Need suggestions to fix this.

  19. Tim I am having many issues with water in my home. We have had 3 people look at the roof which a high pitch on both sides. I know have found on both sides of the pitch my brick stays wet for days. It is affecting my sons room with the base board pulling away and a musty smell which I am sure is mold. We do not know if it is a roof problem a brick problem or a down spout problem. I would love to talk to you. Mindy In Ohio

Leave a Reply

You have to agree to the comment policy.