b'YOUR TOOLKIT FOR BUILDING EXCELLENCEAny building with a portion of the building volume below thearea where surface water collects rather than drain away. outside finished grade soil surface may be exposed to subsurfaceSurface water should be able to drain away from the site water and soil moisture.Any building with a basement,at a sufficient rate so that surface water does not flood a partial basement, or walkout basement needs to be protectedbuilding during design rainfall events for the specific location.from potential subsurface water and soil moisture exposure.Site preparation is the phase to address any problems identified A building that uses a slab-on-grade construction or has aduring the proposed building site selection phase.Sometimes, concrete floor can have moisture challenges due to subsurfacea new building site needs to be elevated to increase a surface soil moisture with certain soil conditions.Regardless ofwater diversion capacity or to get the finished building building design, the building foundation and floor system mustelevation high enough so surface water can drain away from the be able to cope with any soil moisture or subsurface water issues.building.During site preparation is the time to ensure surface To solve moisture problems, the moisture source mustwater will adequately drain away for the new finished building.first be identified.Then based on the moisture sourceA building site located near the bottom of a hill will require and location of the problem, a solution can be developed. the construction of a surface water diversion with sufficient capacity so that surface water flowing to the site will flow around Protecting from surface waterthe new building site.Sometimes the building site elevation Undesiredsurfacewaterimpactsonbuildingsareneeds to be increased to ensure enough diversion capacity can commonlycausedbyrainwater,surfacewaterrunoffbe constructed.A site with naturally slow or poorly draining and snow/ice melt.These precipitation-based sourcessoils needs to use a similar clay type soil fill to increase the cannotbeeliminatedsotheymustbecontrolledelevation under the building so that surface water does not tonotcauseadverseimpactsonabuildingsystem. infiltrate into the fill and collect under the building.A granular material like gravel or sand can be used to elevate the building Severalphasesneedtobefollowedtocontrolbase to a higher finished elevation.Figure 1 graphically shows surfacewaterfromimpactingonabuildinghow low permeability fill should be placed to ensure infiltrated system.Thesephasesincludethefollowing: surface water does not collect under the new building base.1.Site Selectionwhere the building will be locatedIf the building fill base was all granular material, surface determines much of what needs to be done to controlwater in the diversion will infiltrate the fill base under the surface water. building which can result in significant subsurface water 2.Site Preparationproper site preparation has a significantproblems.However, the source of the water is infiltrated impact on effectiveness of surface water control. surfacewaterratherthanasubsurfacewatersource. 3.Site Drainagedetails need to be addressed so surfaceIf the building example shown in Figure 1 had a basement water drains off and way from building on finished site. with the floor below the elevation of the bottom of the surface water diversion and all the fill material was all 4.Exterior wall and roof system selectionthe selectedgranular, a good chance exists that the basement could roof and wall system along with flashing transitions musthavemoistureproblemsduringwetweatherperiods.be selected to ensure precipitation does not penetrate exterior of building. Surface Water Diversion Figure 15.Construction processattention to detail during the construction process must be done to ensure aFinal Grade created withwell-designed wall and roof system is effective. granular fill materialInitial GradeThe proposed site of a new building needs to be evaluated to determine not only how surface water will drainSoil fill with similaraway from the site but also how much water potentiallyNot to scalesoil profile lines water permeability aswill drain onto the site.For example, a site may haveamplified to illustrate point soil at siteexcellent drainage away from the site but is located where a lot of surface water from up the hill will drain toFigure1.Thisillustrateshowlowpermeabilityfill the proposed site.In this example, the proposed building siteshouldbeplacedtoensurethatinfiltratedsurface is probably located in a drainage path for a large watershedwaterdoesnotcollectunderthenewbuildingbase.area.If so, can the proposed building site be moved some so that it is no longer located in the significant drainageThe roof and exterior wall materials protect a building path?A second example of potentially poor site selectionfrom precipitation of all kinds and types.Proper selection is a proposed building site located in hole or depressedof materials and design of transitions between different continued on page: 21 continued on page: 22 FRAME BUILDER - NOV2023 / 21'