Masonry Magazine July 2011 Page. 18
MOISTURE MANAGEMENT
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Out of construction details as quickly as possible. If these two rules are adhered to, there will be less risk of moisture damage to the construction detail.
Learn from the past
HOW DO WET BASEMENTS HAPPEN, and how can they be avoided? In some cases because of an insufficient budget, a wet basement is unavoidable. A cheap lot, poor soils with little or no drainage and the lack of resources to fund a high-quality drainage and waterproofing system can definitely lead to a "wet basement." Sometimes, the best way to avoid a wet basement may be to not build one. Any and all conditions can be overcome, or at least greatly improved, but it won't happen for free. So if the soil conditions of the lot you can afford are not appropriate for below-grade construction and the budget is tight, it is wise to choose another foundation option for your structure.
A dry basement begins with a building site that can be managed to control moisture. The familiar phrase "high and dry" comes to mind when planning a foundation. In the nautical world, high and dry is a bad thing, but in the world of below-grade construction, it's the pinnacle of moisture management perfection. When you get to start with a high-quality building site like the one above, a wet basement isn't very likely! (See Image #3.)
However, do not let looks deceive you. Once you have found an exceptional building site, be sure that the purchase agreement contains a contingency for a soils report generated by a licensed soils engineer. The information used to create this type of report comes from borings cores of soil taken at varying depths in prescribed locations on the building site. Taking ownership of a building site that can't be built on is a bad start. Finding out from the excavator that the soil conditions are bad and will require soil reconstruction and/or budget-busting oversized footings or pilings to support your structure, is also a bad start.
The soils report should also contain information such as the water table and the presence of any potential chemical contaminants. If there is any question about adjoining lots that may leech in contaminants, they should be tested, too. The structural engineer will take the information from the soils report and design the appropriate structural footing and walls that form the basement and support the structure. Once the site has met the critical tests, the next step in the process is jobsite moisture management during construction.
The below-grade construction phase of many building sites is negatively impacted by poor or nonexistent jobsite moisture management plans. A jobsite that is allowed to turn into a mud hole will have long-term negative impact on the soils that surround the below-grade construction and as a result, have a
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16 MASONRY
July 2011 www.masoncontractors.org
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