How to Waterproof a Garage: A Step by Step Guide

Water is supposedly a harmless element, but it can do severe damage to your garage walls. Nowadays, garages aren’t solely for cars, which wouldn’t be much affected by water. 

However, people now store tools, gardening machines, lawnmowers, and more. You’ll want to protect everything inside at all costs to avoid money losses.

Luckily for you, there are multiple methods for waterproofing your garage. Here, we’ll tell you how to waterproof a garage using tanking slurry, and we’ll display alternatives as well.

How to Waterproof a Garage Using Cementitious Tanking

Cementitious tanking, or tanking slurry, as some people like to call it, is a brilliant solution for waterproofing. It doesn’t cost much, and it’s highly effective. Here are detailed steps for using it on your garage walls.

1. Prepare Your Walls

Preparing your garage walls is the first step you should do before starting with the waterproofing process. You’ll need to make sure the wall is clear of any paint, coating, dust, and plaster. It should look as if it’s been just built—with the original bricks fully exposed.

If there are any holes or cracks on the wall, you can fill them with a sealant to close them. In the end, you want your wall to be clean and clear of holes and cracks before moving on to the next step.

2. Prepare the Tanking Slurry

No matter where you buy your tanking slurry, it’ll probably come in powder form, and you’ll have to mix it on site. To do so, you need to be fully protected so it doesn’t touch your skin. You should wear a pair of goggles, a facemask and cover any exposed skin.

The tanking slurry’s package will have instructions for mixing; You’ll want to follow it closely to avoid any faults in consistency. Bear in mind that slurry becomes unusable after approximately 45 minutes of mixing it, and it varies according to the manufacturer. So, make sure to make just the right amount without excess because it’ll get ruined. 

To mix the tanking, start by adding some clean water in a suitable box, can, or any container. Only pour the required quantity by the instructions, and start adding the powder slowly while mixing.

You can use a drill and a mixing paddle to mix the components while adding the powder, but make sure to set the drill on a slow setting. 

After you’re done adding the powder, keep mixing for around three minutes so you get the consistency right. Then, let it sit for one minute and remix. It should then be ready for application.

3. Wet Your Walls

All tanking slurry mixes should be added to damp walls. If your walls are dry, the mix will flake and fall off. Before starting with the application, wet your walls with clean water, but avoid overwetting them.

You want the walls to be merely damp, not all the way wet. Make sure there isn’t any standing water on the surfaces before applying the mix.

4. Tackle the Weak Points

Now that your wall is wet and your tanking slurry is ready, you can start working on the weak points, AKA the wall-floor joints. These joints are highly susceptible to leakages, so dealing with them is essential to waterproof your garage effectively.

Chasing the floor is your way to do so. A 0.8 x 0.8 inches chase will suffice; you can cut into the wall if it’s possible. After you’re done, clean the chase out and remove any dust and debris around.

Apply a coat of your tanking slurry about four inches up the wall and four inches across the floor. Before it dries out, follow it with a layer of a sealant, and get it inside the chase. That way, you create a sealed area between the wall and the floor so water doesn’t get inside. If your floor is waterproof or you intend on waterproofing it, no need to do this step.

5. Apply the Tanking Slurry

The tanking slurry is usually applied in two coats or more, according to the consistency of the mix and the wall’s state. Here are detailed steps for both layers.

First Layer

Start the first coat by applying the slurry in a horizontal motion across the bricks. You can use any brush or roller for that purpose.

You can apply the slurry for any height you prefer, but 40 inches should be sufficient to protect your walls and belongings from any waterflood. If you want to go higher, go for it, but lower than that may serve as a risk in some scenarios.

After applying the slurry to the wall, apply it to the floor-wall joint by approximately four inches across the floor. This step is vital to keep the water off weak points.

If you want to make sure the second coat will cover every inch of the first coat, there’s a nice trick you can do. Tanking slurries usually come in water or grey colors. If you get the two colors, you can use a different one for each layer. That way, any empty spot will be clearly visible, and you can make sure you’re covering everything.

Second Layer

The first layer needs to dry out completely before you apply the second one. It may take a mere two hours, and it may take half a day; it depends primarily on your slurry. You’ll need to wait until the first coat becomes dry to the touch, so it’s time for the second one. Otherwise, it’ll pull off because it won’t be able to support the extra layer.

All that said, bear in mind that you shouldn’t leave the first coat for more than 24 hours. Even if it still looks damp, apply the second one right away.

To spread the slurry once again, stroke your brush in a vertical direction, and don’t forget to apply it to the wall-floor joint as well.

6. Finish the Waterproofing

After you apply both coats of tanking slurry, the wall will take a day or two to cure. You may notice moisture at some points on the wall, but you shouldn’t worry about it. It’s called ‘sweating,’ and it’s completely normal. Different mixes cure at their own rates, but it typically takes a day or two.

As for the finishing, wait for 24 hours after applying the slurry before starting with it. Start by creating a render mix of one part cement and three parts washed sharp sand. Most tanking slurries need to be covered by a 0.4–0.6 inch layer of that render.

If you intend to paint your garage, it’s not recommended to do so directly above the tanking. You can instead dab some plasterboard or use multi-finish.

Tanking Slurry Alternatives for Waterproofing a Garage

While tanking slurry is the most effective waterproofing option, there are some simpler alternatives. They’d come in handy if you don’t know how to mix tanking and apply it. Here’s a roundup of the three most common methods.

Crystalline Waterproofing

The first alternative is the crystalline concrete coating, which is a permanent solution, saving you the hassle of having to re-apply it after a while. Once applied, insoluble crystals will form inside the holes and pores of the wall, creating a waterproof barrier that keeps water out. The crystals also keep growing as they get exposed to water, so the sealant only gets better with time.

If your wall starts to crack, you can always re-activate the crystals so they restore themselves.

Polypropylene Tiles

If you don’t want to make any changes to your garage’s walls, you can at least waterproof the floor to prevent the growth of mold and other problems associated with moisture.

Polypropylene tiles are waterproof and spill-resistant. If you don’t mind paying some cash, use them to renovate your garage’s floor. They’ll look elegant and sleek, and they’ll keep the water out, so it’s a win-win situation!

Waterproof Epoxy

Using waterproof epoxy can be a good solution to your garage problem. After it’s applied to your wall, it takes a couple of days to cure and dry, and then it works efficiently. 

There are multiple benefits of using epoxy. For starters, it doesn’t only protect the garage walls from water, but it’s also resistant to impact, so your wall will take all the abuse you throw at it. 

On top of that, epoxy is corrosion-resistant, so you won’t be seeing rust on these walls anytime soon. The material also protects walls from oil, solvents, and similar corrosive elements.

If you don’t want to use epoxy, you can alternatively get waterproof paint; it works in the same way, but it’s not as effective.

Waterproofing your garage is a great way to keep your belongings safe from cruel winter weather, be aware that water vapor can still form inside your garage so read our article on how to keep your garage dry for tips on dealing with condensation issues if needed.

Recent Posts