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Do-It-Yourself Weekend Project #103
"How to Waterproof Your Basement"

Tool and Material Checklist

Cement, Spray nozzle, Cold chisel, Star drill, Light brush, Wire brush, Epoxy or latex waterproofing mix, Garden hose, Chipping chisel, Pointing trowel, Hammer, Work gloves, Stiff brush, Hand cleaner, Weep pipe

Here are tips and instruction's on how to water-proof your basement. Read these tips carefully and follow the instructions closely. Following these procedures outlined will help you end up with a more satisfactory job - with far less waste and effort.

1. Stopping Leaks and Seepage

Bothered with leaks or seepage through your basement floor or walls? If so, both problems can be solved. However, they are not easy. it will take time and effort, and you will have to do the job right. But, it can be done.

There are three basic causes for seepage and cracks in basement walls and floors. First, the original workmanship may have been poor. Second, the house may have settled causing cracks to appear in either the floor or walls. Finally, water pressure from the outside may have built up and be forcing water through the walls.

Leaks or seepage in basement walls or floors are easy to detect. Moisture will often begin to seep through at the area where the floor and walls join or along any cracks that may have appeared in the wall or floor.

2. Repairing Holes and Cracks Before Waterproofing

If there are no holes or cracks in the basement walls, a water-proofing compound can be applied directly to the walls by steps described a little later. However, almost all leaking basements have either cracks or holes in the walls or floors that should be repaired before any type of water-proofing coating is applied.

Hairline cracks can usually be filled with a regular water-proofing mix. However, cracks larger than 1/8" should be cleaned out and patched, before the water-proof mix is applied.

Special epoxy and latex cement formulas can be purchased for mortaring small repair jobs or for brushing on as a water-proof coating. However, if you are doing a large repair job, you will probably want to mix your own mortar for patching holes and cracks before you start applying the water-proofing coat.

Mortar for filling holes and cracks in cement basement walls or concrete block walls is usually made by mixing one part cement and two parts of fine sane with just enough water to make a rather stiff mortar.

If the water is merely seeping through the basement wall, this mixture of mortar cement can be forced into the crack with an ordinary trowel or putty knife. This will normally correct any small leakage problem. However, if outside pressure is forcing the water through the wall, you will have a tougher repair problem. This type of leak is often extremely difficult to correct.

If water is seeping in under pressure, a dovetail groove must be chipped out for the entire length of the cracked area. This dovetailed groove can be chipped out with a regular chipping chisel and hammer or with a cold chisel.

Enlarge the cracked area before mending it. Use a chipping or cold chisel to create a dovetail space. This provides a holding power for the new mortar when it is inserted. If you chip a vee groove, the mortar will often fall out of the repaired area when it dries. Take time to do it right. It will pay off in the long run.

Holes in a concrete or concrete block wall should be repaired in much the same manner. Chip out the faulty or broken area in dovetail fashion. The dovetail cut provides a holding edge for the new mortar.

When the faulty cement around the edge of the hole has been completely chipped away, fill the hole, with the same mortar mix recommended for the filling of cracks. This is one part cement to two parts fine sand mixed with just enough water to create a stiff mortar.

Place the mortar in the newly cleaned hole, and smooth out with an ordinary trowel. Be sure mortar is pressed into all parts of the hole. Do not leave air pockets.

3. Closing Cracks and Holes When Water is Entering Under Pressure

In some cases it is necessary to position a weep pipe through the wall to permit the outside water trapped against the wall under pressure to escape. In many cases this weep pipe can be installed only temporarily. In other cases it is necessary to leave it in place and drain the water away through a basement sewer trap or with a sump pump.

When water is entering a basement under pressure from outside, insert the weep pip at the point where the wall and the floor join or at a point where pressure is greatest. Use regular patching mortar to fill the crack, starting at the top and working toward the bottom. Starting at the top permits a more secure bonding of the new mortar. Use an ordinary pointing trowel. Fill the crack with mortar completely down to where the weep pipe is installed.

Let the mortar set until it has completely dried. Examine the water entering through the weep pipe. If it has slowed to a trickle, you can probably remove the pipe, fill the hole and eliminate the problem.

If water is still coming through the pipe with considerable force, it is probably wise to leave the weep pipe in place and run the water into a sewer drain with a hose.

If you decide to try and remove the pipe and patch the hole, treat the cracked area right down to the spot where the wall and the floor come together. Next, make a cement plug from the mortar mix which you have previously made. Roll the plug into a cone shape that is slightly larger than the hole to be plugged.

Roll the newly created plug of cement around in your hand until it begins to stiffen. Then stick the small end of the cone-like plug in the hole where the pipe was removed and tamp it into place. It can be tamped into the hole - just like a cork in a bottle.

Hold the cement plug in place with your fingers for 3 to 5 minutes. This gives it time to set. You can probably place some heavy object over this plug during this 3 to 5 minute period to give it plenty of time to dry before letting it be exposed to the full water pressure. After 3 to 5 minutes, you should be able to remove your hand or the object holding the plug in place. By this time, the mortar plug should have dried sufficiently to close off the hole and prevent the outside water from entering.

4. Water-proofing the Wall and Floor after Patches and Repairs have Been Made

After all holes and cracks have been filled and patched according to theses instructions, you are then ready to apply the water-proof mix. The first step is to moisten the basement wall with a fine spray before applying the water-proofing mix. A garden hose with the nozzle set to a fine spray will do the job adequately. Although the walls should be damp when the water-proof mix is applied, no water should be actually standing on the wall surface.

Water-proof mixes of the epoxy or latex type can be purchased for treating basement walls and floors. Most of these mixes require only the addition of water. If you use this type of mix, be sure to follow the manufacturer's instructions carefully. Many modern waterproof mixes will not adhere to walls that have been painted. If you attempt to place water-proof mixes on painted walls, the old paint must first be removed by sanding, wire brushing or sand blasting before the water-proof mixture will adhere to the surface.

It is also important to remember that no epoxy or latex type water-proof coatings will bond to wet surfaces. When these types of materials are used, they should be applied to a surface that is completely dry. If you prefer, you can make your own wall coating mixture of plain cement and water. This should be mixed to form a slurry - a mixture that is about the consistency or cream.

Use a stiff brush and a circular motion to rub this water-proof mix into the wall. Take time to fill every pore in the wall. Start applying the coating at the bottom of the wall first. This is where the water pressure is likely to be greatest. After starting at the bottom , brush the water-proofing mix on up to the top and then move back to the bottom, applying additional layers of the mixture slowly.

The water-proofing mix should be brushed only over the area, where seepage or leakage is a problem. Feather out at the edges until you have completely covered the area where leakage or seepage has occurred. When the coating has dried sufficiently that it does not rub off, spray the area completely with water. Soak it thoroughly and then let it set overnight.

After the wall has dried overnight, wet it down thoroughly with a garden hose and apply a second coat of the waterproofing mixture while the wall is still wet. Use the same techniques of brushing in the second coat as you did for the first coat. Use two coats in all cases. One coat simply will not correct the problem under normal conditions.

5. Packing a Leaking Floor Joint

In many cases the basic leaking problem in a basement is centered near the joint of the floor and the wall. If the leaking is not a serious problem, it can often be corrected by trawling on a double layer of water-proof coating at this floor joint. Use ordinary water-proof coating mixture as previously described. Be sure the floor is clean where the mixture is to be applied.

If the seepage of water is heavy, a dovetailed joint should be cut where the floor and walls join. This can be done with a chipping chisel and a hammer. An ordinary cold chisel can also be used. Chip along the entire floor joint area to create a dovetail groove that will retain the waterproof mix.

Take time to chip this groove completely the length of the leaking area. Chipping out the dovetail groove is one of the most important steps in the repair job. After the dovetail groove has been completely chipped away, clean it out thoroughly and get ready to apply the waterproofing and repair mix. An ordinary brush or a tire pump can be used to brush or blow the small pieces of cement out of the chipped area.

The chipped out areas is then ready for the insertion of the mortar. The regular mixture of one part cement to two parts fine sand plus water can be used for this repair job. You can also use ready-mix ingredients for the same job. Shove small amounts of the cement mix into the chipped out area and smooth out with an ordinary trowel. Do not apply more cement than you can trowel down in 2 to 3 minutes.

It is a good idea to make a slight incline in the patched area, slanting it from the floor upward toward the wall. this provides extra strength to the patched area and helps drain away any moisture that might accumulate in the future.