Brick Walls: Dealing with Moisture Problem

Brick walls are often left exposed for their rustic look but painted so the organe-red color doesn't overpower a room, especially this bathroomBrick 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 …

Attics need ventilation so brick buildings need to breathe to less moisture from inside the home escape

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.
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