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Water Barrier Installation Tips

Water Barrier Installation Tips

If you want to keep water from touching the wood framing members of your house then you need to know a little bit of physics and chemistry. An understanding of gravity and capillary attraction is a must. Let's get to work!

What Goes Up.......

Rainfall or snow is part of a cycle. Water from rivers, lakes, oceans and plants evaporates into the air. It condenses into clouds and when the conditions are right, it falls to the Earth as rain or snow. Gravity pulls it to the Earth and if water gets behind the primary water barriers on your house, it will do everything possible to continue going down.

The water can often take a sideways detour if it hits a seam or horizontal break in a wall cavity. This is why it is often hard to discover the source of a leak. The water may end up 15 feet away from the source of the actual leak.

Capillary attraction can also cause huge problems. This physical phenomenon can actually cause water to flow up instead of down. This happens when two solid objects are very close to one another. The surface tension of the water causes it to cling to the sides of the surfaces and actually flow upwards. If this happens on your home, water might flow up behind siding and the sheathing.

Installing Barriers Water infiltration barriers need to be installed much like roof shingles. Shingles work because they overlap one another. The shingle above laps over the top of the one below. This method of construction stops water from getting behind the lower shingle. Water barriers for walls need the same attention to detail.

The lowest part of the barrier should always lap over the foundation at least 3/4 inch if possible. If you stop it at the top of the foundation, there is a good chance water will leak in over the top of the foundation.

The second row of the barrier should overlap the lower row by at least two inches. Vertical seams should overlap at least 6 inches.

If you decide to use a modern air and water infiltration barrier, be sure to use an approved tape to seal all of the seams. Duct tape is not the answer!

Window Flanges

You must pay attention to details at and around windows. Many modern windows have nailing flanges around the window. The top flange of the window needs to go up under the water barrier. This often means you have to carefully slice the barrier and insert the flange. Be sure to tape the barrier against the flange before you install the primary wall covering. Always think about how you can stop water from getting behind doors and windows. It is critical.

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