Water repellant can help seal up leaky brick walls
Q: As result of Hurricane Irma, I had a leak in the ceiling in the bay area of our kitchen. It happened in the past with other intense storms. I suspect the problem could be water penetrating the brick and/or wind-driven rain entering under the fascia and over and down the inside of the inside face of the brick. Before I dig into this and hire contractors, I'd like your opinion. What's going on and what's the best way to fix it? — Jim McV., Cumming, Georgia
A: Like you, thousands and thousands of other homeowners suffered damage from wind-driven rain from Hurricane Irma. To understand how rain interacts with your brick house, all you have to do is recall high- school physics class: Force equals mass multiplied by acceleration.
Water is heavy. An illustration: Open up your car window as you drive in a gentle rain shower and see what the drops feel like hitting your hand at 50 mph. Now imagine what it feels like at 100 mph or greater. Each water drop that smashes against the side of your house is like a hammer driving the previous water drop deeper into any crack where normal, down- falling rain causes no issues.
Brick walls leak water. The entry point of most of the water is the vertical mortar joints, called head joints. Old brick buildings had a softer, more absorbent brick that was used as a layer on the inside of the wall. This brick soaked up the leaking water and then released it back to the air once the sun and breeze came back out.
Modern brick-veneer construction discarded this wonderful system. Now the water that leaks into the wall runs down the back of the brick. Builders are supposed to install flashings at every horizontal break in the brick wall, such as at the lintel that's hidden behind the roof of your kitchen bay and above and below every window or door.
The wall framing must be covered with a waterproof material that overlaps like roof shingles so any water that ends up touching it cannot get to the wood framing or the interior wall. At the base of the brick wall, there needs to be a flashing that captures the water and redirects it to the outside of the house.
It takes great skill to install all these flashings and membranes. But for you, it's now a moot point. You need to go to plan B.
Your job now is to apply the best silane/ siloxane water repellent money can buy. It may require two coats. What's more, these two applications need to happen within minutes of each other. If you wait too long between coats, the first coat could block the second coat from penetrating the mortar and brick.
The best of these clear sealers have microscopic solids that can help plug up the minute passageways that cause your leaks. It's going to take a little research on your part to locate the best sealer.
When you apply it, be sure two people are working as a team. One will be equipped with a backpack leaf blower. As the person with the spray wand applies the sealer, the worker with the blower directs the wind blast right at the wall, driving the wet sealer deep into the brick and mortar, just as Irma did with the rain.