CONCRETE ANSWERS
Crumbling concrete porch has a drainage problem; what can be done?
Q: My 30-year-old house features a large concrete front porch. One side edge has been crumbling over the past few years, and paint is peeling from a brick design was pressed into the concrete. How extensive is it to repair a problem like this? Who does this type of repair?
A: Your porch is suffering only cosmetic damage and doesn’t appear to have a structural problem, said Frank Owens, vice president for marketing at the Quikrete Companies, which makes an array of concrete products. In the picture you sent, he noted, no cracks extend to the top of the porch, which would signal serious damage.
Owens also called out the gutter downspout, which ends a few inches off the ground and only a few inches away from your porch. Rainwater is probably splashing against the concrete and wicking up into the faux bricks behind the paint. “Concrete is like a rigid sponge,” Owens said, with “billions of bubbles” of air embedded in its structure. When water fills those voids and then freezes and thaws repeatedly, the expansion and thawing of ice makes concrete crumble. It also pushes paint off the surface. So, the first step is to divert the gutter water away from your house. A plastic or concrete splash block that angles the water a few feet away would help. But, ideally, you would hook the end of the gutter to a buried pipe that empties at least 10 feet away from any structure (including your neighbors’) and is at least slightly lower on your lot.
One option for the drainage area is a rain garden – a type of garden bed with spongy soil and plants that thrive even if their roots get soggy. Or the water could go into what is known as a dry well – a covered pit filled with round rocks, with the spaces between the stones giving a rush of rainwater somewhere to pool until it can slowly percolate into the soil. For new construction when a rain garden is part of a formal storm-water management plan, Herndon requires a permit and an annual inspection. But there are no rules about installing either rain gardens or dry wells to deal with gutter water from existing homes, said Scott Brodbeck, civil engineering inspector for the town’s Public Works Department. However, he suggested contacting the office to take a look before you install anything, so that they can offer free advice.
Landscapers can install dry wells as well as rain gardens. For guidance on rain gardens, there’s a 22-page guide available on the Fairfax County website titled “Rain Garden Design and Construction.”
Once the water issue is resolved, you can patch the concrete and decide what kind of finish, if any, you want on the faux bricks. There is no way to perfectly match the color, so if seeing a patch bugs you, follow up by coating the whole porch with a super-thin concrete resurfacer. That does add to the complexity, though.
Good surface preparation is key. A pressure washer set to 3500 pounds per square inch – a relatively high setting – is the best option when there is a lot of flaking concrete or peeling paint to remove, Owens said. When there isn’t flaking or peeling, he recommends using a product such as Quikrete’s Cleaner, Etcher and Degreaser ($18.98 a gallon at Home Depot) If you’re just patching a small area, use the etcher and a scrub brush, following safety precautions on the label.
For patching and resurfacing, use products that contain portland cement, sand, and polymer or resin – plastic-type materials that help the new layer grip and make it more resistant to water absorption. You might need one product for patching and another for resurfacing. For the patch, you probably need something that can go as deep as half an inch and works on a vertical surface, such as Quikrete Quick-Setting Cement ($7.40 for a 10-pound pail at Lowe’s.) For resurfacing, it’s more like ½ inch so that it has minimal effect on the threshold at your front door or the height of steps. One option is the Quikrete Concrete Resur- facer, $27.97 for a 40-pound bag at Lowe’s. Quikrete is introducing a new product, Re-Cap Concrete Resurfacer, that works for both steps, but it’s just beginning to show up in stores. For patching, mix to a putty-like consistency and trowel on. For resurfacing, mix to what Owens calls “a cake-batter consistency” and use a squeegee to coat the whole porch with a layer as thin as ½ inch. After about 5 minutes, when the resurfacer begins to harden, you can lightly brush the surface to add skid resistance. For vertical surfaces, such as sides of the porch, spread the product with a stiff, thick brush.
You can leave the brick areas uncoated, coat them to match the surrounding concrete or paint them to stand out – it’s a decorative decision. Paint probably means the most maintenance over the long term. If you’re handy, you could tackle the repairs on your own, with YouTube videos for guidance. For a professional job, one estimate for the whole job, from prep through resurfacing, is “in the early thousands,” said Kirsten Wilkinson, the general manager for Robert Construction in Falls Church, Virginia.