8 Tips for Waterproofing Your Concrete Slab Foundation:

1. When you buy your new slab, ask the salesperson how to seal the concrete.

2. If you have a high-traffic area, seal it before the slab is laid. If it is exposed to both water and sunlight, there is a good chance that algae will live on it, and you will eventually find it impossible to get rid of them.

3. Seal your slab down with a waterproofing product that contains silicon or silicate (e.g., Silwet 7 or PSA)

It is a common complaint that the waterproofing products on the market today are either ineffective or too expensive. The concrete masonry industry has been aware of this problem for decades, but it has only recently begun to address it.

There are two reasons why these products are not working well. First, they were developed using techniques that don’t work in modern concrete. These techniques were developed using old concrete and designs that no longer work in modern concrete.

Second, the products on the market today are based on formulas that have not been updated for many years and have not been proven to work in modern concrete conditions.

With all of these factors factored in, many people would be surprised to learn that waterproofing a slab foundation is not a difficult task and can be done at a reasonable cost in as little as 3 hours by an average homeowner.

If you want to waterproof your concrete slab foundation, you have to dig down at least 2-3 inches. And then you have to put a waterproofing membrane on the whole thing.

The reason is obvious. When you pour concrete, it stays wet for about a week. Then it starts drying out and shrinking and cracking, and soon the thing is a mess. What you want is to have it last as long as possible. So waterproofing membranes are made of something that dries out first.

There are lots of different kinds of waterproofing membranes, and some are better than others. The one I use is made from recycled tires. It’s not perfect, but it’s pretty good; the company that makes it says its protection lasts up to ten years before setting in place like ordinary concrete…

You’d think that concrete is a highly water-resistant material, and it is. But there are a few things you can do to make your slab foundation truly waterproof.

First, you need to seal the sides of the slab. Concrete, like wood, doesn’t hold water; when it gets wet, it just stays wet. The simplest way to seal a concrete slab is to add a layer of waterproofing membrane on the inside of the slab. Waterproofing membranes come in several forms: housewrap (a fabric), fiberglass, and insulation foam. Housewrap is good for smaller jobs that aren’t likely to get very wet, such as this example from Portland’s remodel blog . In general, though, housewrap isn’t good for foundations because it shrinks over time and the edges tend to curl up.

The best solution for larger projects is a waterproofing membrane made from dense polyethylene plastic with a vapor barrier laminated onto one side. This construction block has a waterproofing membrane on all sides and I’ve used them many times in my own projects. You can buy them at Home Depot , Lowes , or any other large home improvement center. They’re also available online at amazon.com or www.homeworksystemsinc

The first tip is to avoid pouring concrete on your foundation in the first place.

Concrete is not waterproof. It doesn’t permanently fix the roof over your head, and it can’t fix leaks around pipes, or cracks in the foundation. If you pour concrete on a slab where leaks happen every other year, you’re wasting your time.

The second tip is to seal all seams with a waterproof sealant, and then let it dry completely (at least 24 hours).

The third tip is to apply a coating of epoxy or paint to the entire slab surface. The epoxy should cover all seams and any gaps that were missed when two layers of sealant were applied. And then let it dry completely (at least 24 hours).

The fourth tip is to install continuous drainage around your foundation, using plastic pipe, a layer of gravel, then plastic mesh, then another layer of gravel.

The fifth tip is to build up the walls around your house with a solid base coat of waterproof cement (also called ‘waterproofing’ cement). Then install waterproof flashing over all openings, such as windows and doors.

The sixth tip is to build up the walls with concrete blocks that are properly proportioned for construction purposes — not too big and not too small

Concrete is the foundation of your house. It is the most important thing you build, because, when it works right, it will last a century or more under any kind of weather. A good foundation is also beautiful.

For as long as I can remember, everybody seems to have had a problem with concrete. It gets messy and expensive without lasting forever; water seeps into it, making it rot and crumble; it cracks even if you don’t water it; and in cold weather it freezes, causing leaks. It’s common for homeowners to think “this thing just isn’t working.”

I have made some progress in solving those problems. But there are still many unanswered questions about waterproofing concrete. For example, which kind of cement is best? What additives should be mixed in? How much water should you pour on the cement? What temperature should you pour it at? And so on.

Another way to make concrete waterproof is with a material called latex. This is a thin, transparent film that you spread over the entire surface of the slab. The idea is that water can’t penetrate it.

Then you build up the rest of your retaining wall on top of it, and you don’t worry about rain.