WHAT IS A DRAINAGE PLAIN?

A drainage plain is simply the area between the paper and the finished building exterior component such as siding, conventional stucco, or an efis application etc. this area between the wall is somewhat expected that there can be water present in this area of the envelope. Its sole purpose is to allow the water to drain down the wall and exit at the bottom of the wall system through drainage ports. This can be a woven plastic mat or can be pre formed groves on the back of foam panels(styrofoam) mainly used on concrete buildings with a glue on application, or just a void between conventional and the building paper. This is very important that the paper does not have a reverse lap. A reverse lapping of paper happens when a non trained worker installs the paper with the over lap facing to the top this allows water running down the paper above immediate entrance into the wall and creates a trap for the water to penetrate into the interior walls.