Exterior Basement Waterproofing Membrane

Connecting HDPE Pieces

There are two ways to connect multiple pieces of HDPE together. One method is to overlap the HDPE and use our double sided seam tape to connect the two pieces. The other method is to butt the ends together and use our 17 mil single sided seam tape to create a solid connection.

Overlap Method
(for underground installations)

The overlap method is best used when connecting two pieces of HDPE in a buried application. Due to the overlap, a ridge is exposed which is not ideal when installed in exposed vertical or flat installations in high traffic areas as there is a possibility of an object catching on the ridge and pulling the two pieces apart.

In a below ground installation, the large overlap area provides a more water resistant connection as well as enhanced protection against tree and plant root intrusion.

End to End Method
(for exposed installations)

When installing HDPE on a wall, floor or anywhere that is exposed, the end to end method provides a secure connection and does not leave any ridges exposed to potential catching by a person or object.

SHIPPING TIME

• All HDPE rolls ship for free (standard ground, see map)
• Call: (800) 604-5537 for pricing and shipping questions.

Shipping estimates shown on the map pertain to this specific product only. HDPE orders typically ship same day if the order is placed before 12:00 noon CST. Transit times displayed in the map are listed in business days, and are approximate. Transit times are subject to stock levels at regional warehouses.  The day that the order is shipped is not counted as a transit day.

Waterproofing Your Basement

If the moisture is minor, you might be able to repair it yourself but in most cases, you will have to hire a foundation contractor. If you want to waterproof the basement walls, the following suggestions will get you started in the right direction.

The first step is to find out where the water is coming from before waterproofing. Because concrete is very porous, you will see wet streaks caused by water coming in. You should look for streaks along cracks, at the corners of windows, between mortar joints for cement block walls, and around pipes where they enter or exit. Pipes will include a water-supply line or a sewer pipe.

If the surfaces of the walls are wet, you will have to do a thorough investigation before moving on. You can perform a simple condensation test. Dry a section of the wall with a rag or cloth and then place a one-foot square piece of aluminum foil on the wall using duct tape. After 24 hours, peel off the foil and check how the underside of the foil feels. If it's wet, water is coming through the wall from outside. The moisture could be coming from somewhere else if the area is dry. If you have a basement shower, that could be the culprit. If that's the problem, it's actually pretty easy to correct by installing a vent fan in the bathroom to direct steam outside.

Keep in mind, you must know where the water is coming from before you can waterproof the basement walls.

As mentioned, cement is very porous, you can usually see wet streaks that will let you know where the water is coming in. Look for streaks along cracks, windows, joints, and around pipes where they enter and exit.

Fill In Cracks Using Hydraulic Cement

Make sure to check for cracks at the bottom of the basement walls. When a foundation is poured, the footing is poured first, this is a wide flat base made from concrete and reinforced steel designed to support the walls. The walls are poured on top after the footings harden.

Although this is standard construction, it can form a “cold joint” which is a weak spot in the foundation between the wall and the footing where cracks can form when the foundation shifts or settles along with lateral pressure from the soil.

Sealing cracks is a relatively easy DIY job that involves filling in the cracks with hydraulic cement. Hydraulic cement contains additives that cause the cement to expand and set quickly. It's mixed with water to form a heavy putty consistency then pressed into the cracks using a finger that is gloved or using a putty knife. Before proceeding be sure to read the directions on the product's package.

As the hydraulic cement expands, it will push deep into the cracks and crevices to form a watertight bond. Only mix as much as you can use within 3 minutes because that's how fast it will start to set.

Be Sure To Check The Window Well For Leaks

Window wells are frequent causes of leaks because they will hold water if you do not have a good drainage system installed beneath the window well at the time the house was built. In most cases, water will pool around the bottom of the basement window and then will start to leak in.

It can be difficult to install a window well drainage system in the aftermath. You have to dig 2 feet lower than the window well area and fill in the space with gravel to have the rainwater scatter instead of collecting in the well. Block around the window with a caulk that is suitable for use on masonry. Also, install a sloped window well cover over the window well to direct rainwater away.

Do Not Apply The Sealant Over Painted Walls

If the walls are painted, you will have to remove the paint before applying the sealant as it only adheres to bare masonry. Many older homes have several layers of paint which will have to be removed by professional sandblasters known as blasting contractors. You can remove the paint with a wire brush but it will be very time consuming and tedious but inexpensive. Also, check for efflorescence or white deposits that form on the surface of concrete walls from constant moisture. You can use muriatic acid just make sure to read the manufacturer's instructions.

Down the road, take other steps to keep water away from your foundation. You can start by removing foundation plantings and flowerbeds that require watering as the water can easily seep into the basement. Inspect and repair gutters and downspouts to make sure they are directing water away from your home. It's also a good thought to grade your yard away from the foundation by at least a 2 % slope.

Another thought is installing an exterior drain tile system. The problem is, it's very expensive running $10,000 or more. The soil has to be excavated around the outside of the basement to install a perforated drain at the footing level. A waterproof membrane is usually installed on the outside of the basement wall and the system requires putting in a buried sump pump where water will collect and then be pumped to the surface. Also, this job must be done by a foundation contractor. The upside, it will greatly reduce basement water issues.

Install A Drainage Channel

A great alternative for having dry basement walls is installing a drainage channel beneath the floor inside the basement. This drain is similar to the exterior drain tile mentioned above but it's located just inside the basement walls then new walls are built on the inside of the drain so the initial basement walls are not seen. This is another project that must be done by a foundation contractor and will cost around $5,000. When all is done, you will have new dry walls and any residual water that seeps through the old basement walls will be directed to the drain channel and pumped out.

Additionally, for a second layer of protection it is a good idea to install a plastic membrane on the outside of the wall to help to prevent surface water from puddling near the foundation wall which will many times end up leaking through the wall and into the basement.