Brick walls can present many challenges, especially in older buildings. While we like preserving the old brick walls and leaving them exposed, it's important to understand brick wall construction and maintenance in order to minimize problems.
A customer called my handyman business. She had purchased a condo in an old brick building and her unit was on the 3rd and 4th floors. The top floor “loft” includes a bedroom and bathroom. The young woman was dealing with several different problems after her first winter in her new home. We did a lot of research to make sure we considered all aspects of her space, to find a solution that would address her problem with creating other problems.
The Customer's Problem
The room is very cold and drafty so she'd like to add insulation and then sheet rock (also called drywall) over the brick wall. As the room is fairly small, she asked if we could minimize the loss of space by using strapping versus standard 2 x 4s to frame the wall to support the new drywall.
The most important item that came up during our discussion was the “fuzz” she found on the brick wall behind her dresser. While at first this clue to a bigger problem didn't jump out at me, with further research it became an important factor in how we reduced the flow of air coming through the brick wall.
Researching to Find the Right Solution
The fuzz alerted me to a potential moisture problem. It was the possibility of moisture problems that indicated we needed to research the problem and the solutions carefully. Which indicated more research was needed before proceeding as applying a moisture blocking paint could potentially cause more problems. We reviewed a number of articles, and the best …
- Brick Leaks at Ask the Builder
- Brick Houses and Vapor Barriers at This Old House
- Weatherproofing at the Old Virginia Brick
- Solar Driven Moisture in Brick Veneer by Building Science Corporation, the most technical of the articles reviewed including this diagram that illustrates the multiple air pockets used for ventilation following today's home building standards.
Research involved reading 8 to 10 articles. Unless you are very familiar with a topic, you should never trust a single information source but rather review at least 3 to 5 good articles (or more) until you see common thread(s) through all/most of your source material. You want to be certain you've identified all the key factors, and only then are you ready to develop a viable solution.
Where does the moisture come from inside our homes? A key factor I had overlooked initially and only 1 of the articles covered this point. The fact is we create significant amount of moisture inside our home's, which must be allowed to escape to the exterior. Below is a list of moisture creating culprits:
- Baths and showers, i.e. the bathroom in the loft
- Dish washing, hand washing, etc.
- Breathing gives off a lot of moisture … really, it does!
- Surface water evaporation from fish tanks, toilets, etc.
- Furnaces and humidifiers
Attics Need Ventilation
Like your attic (the loft here is really finished attic space), proper ventilation is needed to insure that moisture isn't trapped in the room, or worse, inside the wall where mold can grow undetected.
Brick Wall Facts
- Brick walls are never waterproof. Bricks and mortar are able to absorb a great deal of moisture in multiple ways and must be able to breathe to eliminate this moisture.
- Water can enter through tiny cracks between the bricks and mortar. When mortar doesn't completely fill the vertical joints between bricks, these “head joints” will allow water to flow.
- Bricks and mortar have tiny passageways that like a sponge, suck water in … and release it quickly.
- Older homes may experience leaks but this rarely causes problems. With two or three layers of brick, they can absorb a lot of water and when the sun appears, they will release the water back into the atmosphere.
- Newer homes have a single layer of brick veneer. When not constructed properly with flashing and weep holes at the bottom of the brick wall, the trapped moisture may cause wood framing to decay and mold to grow.
- Moisture is a problem in most climates as air conditioning creates cold air in warmer temperatures.
Solution to a Drafty Brick Wall
If there is no visible moisture/water problem along the floor next to the brick wall, then the current ventilation is working and we probably don't want to alter air flow between the room and the exterior. We can only give recommendations – the ultimate decision always lies with the home owner when it comes to home maintenance and repairs.
- Use a vapor-permeable barrier like Tyvek. It is designed to reduce air flow while letting water vapor from inside your home, migrate to the exterior. These water repellents are designed to penetrate into the brick and mortar, coating the insides of their tiny passages while leaving the passageways open so the brick and mortar can breathe.
- Don't want to use a film forming sealant that creates a continuous barrier on the surface as this will stop water from getting in … and getting out! If you still want to apply a moisture barrier, please read Brick Leaks at Ask the Builder first.
Will Brick size ….Brick Vents help on a full masonry home built in 1945 in the Midwest. Occasional moisture/mold issue on the interior plastered walls. Not sure what type of sealers may have been put on the exterior brick
Tom, I’m not familiar with brick vents but maybe they’re the same as brick weep holes, a common way to let water/moisture behind a building’s siding to drain out & air circulate so the space dries out. You may have other problems so I suggest you read following articles:
We have a brick wall in our outdoor front entrance way to the house. It is covered and the garage is on the opposite wall. We put in a new stone patio entrance and ever since we have a lot of moisture on our brick wall. It seems be be coming up from the ground. Do you know how to fix this issue? It is now causing damage to our brick and mortar
Josee, My best guess is the stone patio is trapping water. You probably didn’t know that the patio needed to be sloped to make sure water drained off & away from the house. Brick is porous so it may be wicking water up from the ground or simply absorbing moisture from the air in the entryway. Why don’t you put a dehumidifier in the entryway & see if it can dry out the brick … and then you’ll have a better idea what to do next.
Hello! I have a two-story brick house, built in the 1880’s, in the mid-Atlantic area. There was an addition built in the early 1900’s that added (among other things) two bathrooms: a half bath downstairs and full bath upstairs (stacked above the half bath). They both feature an exposed brick wall, which was the exterior rear wall of the original house. Recently I noticed an issue with the plaster in the dining room (in the original part of the house and backs up to the half bath). The plaster is powdery and crumbling, which I understand is evidence of a moisture problem.
My question is, would the moisture from the shower in the upstairs bath be enough to cause problems in the dining room downstairs? The shower is not on the brick wall, and there is an exhaust fan, but the brick wall is unsealed. Would it be helpful to seal the bricks in the bathroom, or is the going to cause issues later since the bricks then couldn’t breathe?
Naomi, You do have a moisture problem & yes, water follows gravity so moisture that seeps into the walls from the upstairs bathroom will travel down to the dining room (in attics you can spot roof leaks by the black lines that travel down the easiest path). Be careful about sealing as that could trap water in the walls & make things worse … as mortar & concrete are porous which most people don’t understand.
Suggest you read this article, Masonry And Moisture—What is the Worst That Could Happen? carefully. You can buy an inexpensive moisture meter (get one with prongs) to check on moisture in the walls/ceiling … and you’ll probably want to get professional help.
hi my name is jenny
I was hoping to get some advice pls i do all the repairs that of course im aloud too around my house . we brought the house 10 years ago and the last few years ive noticed moss growing on my front porch on my bricks so my question is how do i find the leak where its coming from cause we are going to sell and i wont too fix the problem before we sell.
thank you jenny cruise
Jenny, You say the moss is growing on the bricks on your front porch – is the porch covered or exposed to the elements? Most people don’t realize that concrete and bricks are porous, so they can hold the moisture that supports moss … and mold if there’s also a food source. Here are some articles I found that should help you get rid of the moss:
I have a brick pony wall for my sunroom. The new insulated vinyl wrapped windows are supported by aluminum rails as is the polycarbonate ceiling. I have been using a dehumidifier this winter which is helping. However this is in the rainy northwest. The brick are still very wet inside. Even causing water along the concrete floor . Not sure what I should do?
Judy, I had to do some research as I’ve only personally sealed the inside of a stone walled basement which we did seal to keep the water out. I found a good article that confirmed you can (and should) seal the exterior of your brick pony wall. I read through the article which is very detailed which is good … so please read How to Seal Exterior Brick, reread & possibly write down the steps so you don’t miss one (teaching my granddaughters how to cook & the repercussions when they skip a step are bad, throw it out).
Hi Tina. We have a two level old row house with a brick wall. The wall on the second level became moist and the paint began bubbling and plaster was moist. Our contractor recommended pointing and sealing the exterior brick, which we did. Now we are understanding that you should not seal the brick. But it is already done. The moisture has nowhere to go but inside. How do we dry out the moisture at this time? Thanks,
You have now stopped water from outside coming into your home. Now it’s time to deal with the moisture you’re generating inside your home. Here are a couple of quick things you can do … and I’ll write an article on this in next 1 to 2 weeks.
Can I have some advice please?
I have a dehumidifier running in a small hallway.
It faces a wall of single, plastered brickwork which has a bath and shower behind it.
I have 7 litres of water removed in a few days.
All doors closed, toilet seat down and the wall is dry to the touch on both sides below bath level
The hallway has been painted.
Can all of that moisture have come from the paint only?
Ann, There is a tremendous amount of humidity in the air almost anywhere in the US, with the exception of desert climates like Arizona (they think it’s humid when > 12% humidity). At the other end of the spectrum, Florida has average 75% humidity and much of the time my HVAC system is running, it’s to remove the humidity more than lowering the temperature.
What’s probably most annoying for you is having to empty the dehumidifier so often and that water is heavy. Suggest you focus on that problem. Look at the space & where the exterior walls are. Try to find a new location for your dehumidifier that’s on an outside wall where you can run a hose line directly outside to eliminate carrying water. What we’ve always done is put the dehumidifier on a shelf in the basement, next too and higher than a window so we could run the line outside … as you only need to do this in warm weather. In the winter, when you heat your home it dries out and you need a humidifier … LOL!
I need help please.
We changed the roof, replaced the windous, eaves but the wet wall is still on the top sides of the windows
Do you have any idea what to do please?
Is the problem in one area or multiple sides of the house? My first guess is maybe the bathroom fans, or more frequently it’s the dryer vent that goes into the attic but not outside, that’s adding moisture that then follows gravity downward … but not sure why it would only occur at the top of the windows. Another idea – is your HVAC air handler in the attic and leaking?
I have the same issue. I have a two story brick house built in the 1960’s. We have moisture (condensation) building on the top of the window brick and sides, dripping down. We are unable to trim out the window now. We close the heater vent and door during the winter when it’s not being used. There is no bathroom upstairs but one of the two rooms doing this has a bathroom directly below it. I’m not blaming the bathroom for this issue. Roof / attic insulation is new with proper ridge venting, but there are two old triangle vents located above these two windows for the roof to vent. Could those be part of the problem. Any recommendations please.
Donna, Sounds like you’re working hard to resolve this moisture problem and all I can offer are some other ideas but no guarantee:
Best of luck finding & solving the problem.
I have a brick home built in 1920
I have a wall that was so wet under window sill the sheet rock was mushy & it’s crumbling & the wood laith slots are also crumbling in your hand.
Below this room is the basement & I am finding clear water coming out like a river in the same corner as the rotten wall above.
All the brick are soaking wet in the wall
The brick are black like they used a liquid tar or something when they built it
There is no insulation at all
I don’t know what to do
Window is caulked well ,we had wall repointed a few yrs ago
Where is this water coming from?
Carol, You’ve certainly got your hands full so let me try to answer some of your questions.
Where is the water coming from, as that’s the source of the problem? Here are some possibilities to explore:
– Do you have gutters on your roof, with downspouts that move the water away from the house?
– Does the ground outside your house slope towards the brick wall? The water can enter your home at ground level and travel up the wall as it’s absorbed by the framing or drywall, even if there’s no insulation.
– Is the room a bathroom with the shower/bathtub on the wall with the window problem? or is there a bathroom above this room where there could be a hidden leak causing water to flow down that wall? … is the wall mushy above the window?
The last one is from a real project. What started out as a bathroom remodel ended up including a new window, drywall & insulation on the outside wall. There had been a leak in the window for years which the homeowner finally admitted.
So to get started, I’d suggest drawing a picture of the wall and everything above, below & to the side. Then inspect everything to see if you can isolate the problem so we can take the next step.
My bedroom is North facing. And is single brick. In winter black mold appears behind chest of drawers. With new replacement windows it is a problem to cover walls with anything of a thickness as it would stand proud of the window line.
Ron, You’re in the UK so likely you live where it’s cool & humid much of the year. When you say “single brick” this sound like the brick is used as the exterior siding but not structural in any way. The problem then would be the mortar between the bricks is failing and water is getting behind the brick, absorbed by the insulation and the drywall opposite the brick. This is a serious problem as you’re only seeing a small part of the black mold, as I’m fairly certain there is a lot more mold inside the wall.
It’s pretty likely you’re in for some fairly expensive repairs on both the outside of your house, inside the walls (insulation that gets wet is ruined and will need to be replaced), possibly structural repairs to the wall if this problem has been there for many years … and replacing the interior drywall will be the easiest part of the solution.
You definitely need a very experienced handyman/remodeler to review the situation and I strongly recommend you let them open up the wall behind the chest of drawers big enough to accurately estimate the scope of the damage. This won’t be fun but this isn’t a problem you want to ignore as the mold can affect your health so … good luck.