03-18-09 HIA Agenda - Laserfiche WebLink

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March 13, 2009 William A. Becklin, P.E. Becklin & Whitney 1628 Co. Hwy. 10, Suite 17 Minneapolis, MN 55432 Office: (763) 785-3899 RE: Canabury Square Exterior Renovations and Repair -Project Analysis- Attempting to complete the project from the inside. Mr. Becklin, Before we look into the possibility of performing the work on the Canabury project from the inside, we first need to explain what the problem is with the building as a whole. in order to do this an explanation of the current exterior needs to be attempted. The existing stucco on the project was installed around 35 years ago. The stucco was applied correctly per the practices that were accepted at that time. I was able to look at the wall in one of the units that has all its interior sheetrock removed as part of a renovation by the owner. It consists of a 2 x 4 wall, fiber board sheathing, probably a layer of tar paper, wire mesh, and then the applied stucco. This system has performed very well over the years but it has succumb to the inevitable cracking and leaking due to the expansion and contraction caused by the freeze/thaw cycle that we experience in Minnesota. Once the building begins to settle and shift over the course of its life these cracks are caulked in an attempt to keep the building weather tight. Some areas may have been missed, or the caulk began to break down causing leaks to slowly develop over time. These small, slow leaks are what contribute to the building structure failing. Every opening in the building exterior becomes an area where water intrusion can, and probably will occur. Once the water has entered the shell (in this case the stucco) of the building it will be drawn into the building sheathing and eventually the framing through capillary action. An example of this process would be setting a dry sponge near water. As a result of the limited flashing techniques of the time, the water is not channeled down the wall and out the bottom where it would drain harmlessly onto the ground. Instead, it is trapped in the wall contributing to mold, rot and eventually structural failure. With the lessons learned by using buildings like Canabury as case studies, buildings codes have changed the way that we install windows and doors and how we finish the exterior of all buildings. Today the building shell acts as a water diversion system that forms a continuous drainage plain to allow the water to be stopped at the building wrap and then channeled to the outside of the building with proper flashings, No matter what siding material is used it will fail at some point in its life cycle. When water penetrates the siding it must have a place to go. At the current time that is into the wall cavity. Today, by having better windows with flanges, detailed flashing techniques and a building wrap we are able to allow what water that does penetrate to be collected and drained to outside, It is impossible to know without removing drywall on the interior or stucco on the exterior, what areas may have succumbed to deterioration. it would be very difficult to do use exploratory "core sampling" of the shell to determine if mold or structural damage is present. However, we do have the luxury of case studies in the neighborhood that clearly show us what the current condition of Canabury probably is. Because of this knowledge we are able to make an estimation of what work needs to be done and how we need to do it. ® ~ TWIN CITIES SAINT CLOUD 2277 W Hwy 36 • Suite 210W, Roseville, MN 55! 13 60128th Avenue South, Waite Park, MN 56387 CONSTRUCTION 651-227A631 Fax651-227-0132 320-253.3354 Fax320-253-3795