I devote a chapter in the book to basements. Why? Basements are the go-to shelter in many storms. If a tornado hits, you’re much safer in a well-constructed basement than you’d be most places.
One topic I didn’t have room to address properly was keeping water out of your basement. This information applies to any structure below ground, bomb shelters and underground homes need to stay dry too!
1) Choose a good location to build on. Is your home near a river that regularly overflows? Look at the surrounding ground. You want your home on higher ground. Water will run naturally down and shed from your home. Don’t select a location where water will pool.
For a new home you can get a CLUE report. CLUE stands for Comprehensive Loss Underwriting Exchange. It’s like a history of insurance claims against a property. If a home has been flooded multiple times in the past, it will flood in the future.
A controversial topic is the government’s insurance program for flood prone areas. floodsmart.gov. If you live in some areas, your home will be flooded. It’s just a matter of when.
Don’t build on a steep hill. Heavy rains move soil and could damage your home. I feel a bit queasy whenever I see a home precariously perched on a steep slope. Why ever did they build there?
2) Augment the natural flow of water away from your home. This can be done in several ways.
a) For sure, clean your gutters. Purchase extensions and run your gutter pipe at least 8 to 10 feet away from your home.
b) Look at the grade near your house. The ground should slope away from your house. This will help carry rainfall away. If necessary, purchase dirt and bank it up around your home. This is a must do if your grade isn’t acceptable.
c) OK. You’ve got squeaky clean gutters. Your grade is great. Just because of your location and other sources of water pouring into the land your home sits on, you still have issues. There are three common solutions.
You could build a French drain to channel water flow away from your property. You can search Youtube for “French drain” to learn more. Basically, a French drain is a channel which water can take to move away from the area you want to keep dry. It’s like an express lane for water. These are constructed with plastic drain pipe, filter cloth, and stones or pebbles. Don’t build a German drain by accident!
You only need a French drain if you must move substantial amounts of water away from your home.
d) What if you’re in a relatively low location and water in your French drain doesn’t have anywhere to go? It’s time to learn about building a dry well. A dry well is basically a hole in the ground and channels leading to the hole. Water flows from the channels into the hole and from there can seep into the ground. If the reservoir fills too rapidly, there is a pop up where water can come out the top. Rocks around and below the installed well aids in water flow.
You only need a dry well if your French (not German!) drain doesn’t have anywhere to shed water.
e) An alternative to French drains and drywells or a supplement to them is a sump pump. French drains and dry wells are pretty easy to construct. They just take a lot of digging. Once built they do their job without any further effort or expense from you.
Sump pumps require power to pump water away from your basement. This Old House has a nice video on youtube explaining how to install your own sump pump. Most often these are put in the basement in a corner where water collects.
The concrete floor is chiseled out to make room for the pump and then resealed around the pump container.
When the water level gets too close to the floor of the basement, the sump pump automatically turns on and pumps water away from the structure.
If a power outage concerns you, there are battery backup sump pumps.
A sump pump is a great alternative to French drains and dry wells. If you’re an urban prepper with close neighbors and no real lawn to build French drains and dry wells, a sump pump is perfect. A sump pump is a great last line of defense to keep water out of your basement.
3) Seal your basement’s walls against water. This is another one of those things you really should do if the interior walls of your basement are accessible.
If water builds up on the outside of your basement, it will exert tremendous force against the walls. Water will flow in through cracks, loose mortar, and enough pressure will push water right through concrete block.
The solution is simple.
a) Coat the walls with a good waterproofing paint. It’s an easy job. If you go into a hardware store, you’ll find waterproofing paint. Zinsser has a neat little brochure “Guide To Waterproofing” available in many hardware stores.
Go with an oil-based paint like Zinsser’s WaterTite in the red can. It says it can withstand 34 pounds of water pressure. Before applying the paint, clean the surface and seal any cracks. Double coat. As with all painting, how well the job turns out depends on how well you prepare the surface. We don’t care about pretty. We care about waterproof.
Zinsser makes polyurethane sealant for caulking corners and areas where expansion and contraction can occur. You can purchase hydraulic cement for filling in gaps. Hydraulic cement expands to create a watertight seal. Paint can fill in small cracks.
b) If you go to the wall and it crumbles in some areas due to previous water damage, you can fix it with surface bonding cement. Surface bonding cement is a special cement which contains tiny fiberglass fibers which lock the cement together. It’s exceptionally strong.
The theory is that you can just stack up blocks and slap a coat of surface bonding cement across them. It will be as strong as using mortar between the blocks.
Hint: If you’re repairing a wall with mortar, rather than troweling it on, you can pick up a handful and throw it at the wall to get it to adhere. Wear safety glasses!
4) If you’ve followed the advice this far, your basement walls shouldn’t leak. You’ve reduced the water pressure against them by sheding water away from them. The walls have been waterproofed. There’s one more potential source of water.
In some cities, when it floods badly, sewers backup. In general, backups are good. Carry a backup gun. Backup your computer. Sewer backups are bad. In heavy rains, if a sewer has no where to take the water, it can follow the path to your tub drain or your toilet. Water will pour out of your toilet. Icky. I know.
In other cities this doesn’t happen. Ask around if this is an issue if you move to a new home. In some areas, the sewers were sized to carry away not only sewage, but the gutters of yore drained into the sewer system.
If this is an issue in your area, you can install a one-way valve, which prevents sewage from backing up into your home. This link (to youtube) will show you a three part series about installing a Mainline Fullport Backwater Valve.
5) In the book, I began the chapter on basements with a discussion about the construction of boats. In yet another way basements are like small ocean going boats: You really don’t want water inside them, but you should plan for water getting in anyway! Despite your best plans and efforts, always assume water will win in the end. Keep this in mind if you remodel your basement.
Avoid things like carpet which will sop up water like a sponge. Don’t use regular paper faced sheetrock which can harbor mold. Pay a bit more for the fiberglass faced stuff.
If water does get in your basement, have a dehumidifier and extension cord handy to quickly dry it out. Powerful blower motors or fans help speed up drying out.
Charlie Palmer -author The Prepper Next Door