This article was provided by Greg Truman of Urban Contracting "Defining the Art of Excavating"
www.urbancontracting.ca 250 215 8006
Preparing your yard for the new Renovation.Left alone, water is one of the most powerful forces in nature. Properly collected, controlled and directed water becomes manageable and predictable. Preparing your yard for that new addition is one of the most critical steps in assuring your investment doesn’t wash away or at the very least settle, shift and crack. A sound foundation is the cornerstone of your project. Companies like Flywheel Building Solutions may be involved in the preconstruction and final finish stages to assist homeowners with all the aspects of the project assuring that any details large or small are being properly reviewed and completed as per the local building codes. Excavating contractors like Urban Contracting or your building contractor are also excellent sources to help you design and properly complete your project. If you’re the kind of homeowner that likes to get involved and assume the roll of the General Contractor here are some steps you should follow;
The first consideration before you start excavating, for the new addition, is reviewing the general layout of your slope around the property and to assess the type of ground conditions or geology of your property. Controlling water runoff or ground water starts with understanding the slope of your property and where you are going to direct the excess water from the new structure. Mother Nature over millions of years has shaped the landscape as we see it today. When we remove the earths natural ability to absorb water in the native soil and replace it with hundreds of square feet of roof we must direct and control the potential deluge of water to locations that are designed to adequately absorb and disperse the water. We do this by directing the water into pipes that flow to drywells or some form of seepage bed located 3 meters or more from your buildings foundation. The Okanagan Valley offers diverse geological soil conditions. Ground conditions will vary from property to property, homeowners can be faced with; bedrock, silt, clay, hardpan, sand, gravel or a combination of all the above. When assessing the degree of slope required to control your surface water the homeowner must consider the size and type of drywells required based on your geological conditions. As an example, a property with a gravel base would require substantially less area to direct and absorb the water V.S. a property with bedrock or hardpan conditions. Again, if you not sure it’s best to consult your contractor, engineer or building inspector for the location and size of the collection system.
Ask yourself these questions; What impact will the new addition have on your existing yard? Will I need to relocate irrigation lines or small plants and shrubs? Is my septic system or drain field in the excavated area? If so, does the septic system still meet the Ministry of Health’s setbacks or usage guidelines? What is the location of your domestic water line? Am I on a community sewer system, Is the pipe near or under the new addition? Do I have an underground or overhead electrical connection, if so, where is it located? What impact will the new roof runoff have on your existing drywell or water collection system? What are my ground conditions? And finally, what will happen with the surface ground water after your addition is complete?
Once you have assessed your property its time to redesign and redirect your surface and ground water to a proper location. It is very important that the foundation for your new addition be kept dry and is capable of dealing with any unexpected water from either underground or surface water. Ground water or surface water that is able to penetrate your footings will over time cause serious damage. Your building will settle and drop creating instability and noticeable damage. To solve the issue, homeowners have the option of using a 4 inch plastic perforated product called “Big O” or a more ridged perforated 4 inch PVC type pipe. The perforated pipe, that allows water to enter quickly, is carefully laid next to the entire length footings and completely covered over by the locally approved drain rock and a filter cloth used to create a barrier between the soil and the clean drain rock to help prevent silt-out or contamination. The pipe is gently sloped along the foundation until it reaches the drywell located at a specific distance from the building.
So, you have completed the required perimeter drainage system and now its time to backfill your new addition. It is recommended that the surface slope of the property be a minimum of 2% from the building allowing surface water to naturally flow away from the building. Some regions or cites have adopted slopes of 7-8% or more. It is also advised the material being used to backfill your structure be compacted by mechanical means. Poor compaction of the surrounding excavation will allow the lose ground to settle and cause low spots allowing water to pool. This pooled water will naturally drain down the side of the concrete wall further settling the un-compacted ground. If not corrected, pooled areas will cause damage to the footings, sidewalks or driveway as the ground continues to settle. Once again, depending on ground conditions and the potential volume of water from the surrounding area, the homeowner should consult their local inspectors or building department for recommended guide lines or suggested slopes. If your land is properly sloped away from the building the perimeter drainage system my never see any water.
The single most neglected item that will cause serious damage to your building and surrounding structures are the roof drains. Remember, you have redirected hundreds or thousands of square feet of land that was previously able to absorb the water naturally and now have it focused to your new roof. If you don’t control or redirect the water to a new location you are allowing high concentrations of water to be distributed to just a few down spouts. If your property is not sloped correctly the water will very quickly find the path of least resistance. This path, leads directly to your footings, under your newly poured sidewalk or freshly paved driveway. We have all visited someone’s home and seen the sidewalk slabs that are misaligned, the retaining wall that looks like it may fall over any day or the driveway that has cracked, shifted or sunk. This damage could be from poor compaction during construction but most likely is from misguided surface water.
The installation of a three or four inch solid PVC piping system connected to all the down spouts on the building is ideal to control and manage any roof water. The PVC pipe is normally run along the side of the building approximately six to twelve inches below the surface. In addition, any large surface areas like your driveway, decks, pool, grass and patios should also be collected and directed to the same drywell or a series of drywells depending on the layout of your property. This new system should not be connected to your perimeter drainage system that was installed for the footings. Find an area away from the building suitable to support the potently large volumes that may occur from rapid runoff in the spring or heavy rainfalls throughout the years.
Now that you have controlled the water in your yard is time to reinstall the irrigation, any additional plants or that new patch that is required to complete your landscaping. Any irrigation located near the building should be monitored and operated manually every few months to assure it has not been compromised. Be aware that newly excavated areas can often settle causing a break in the irrigation system. Although you have just designed the property to deal with surface and underground water a failed irrigation system can cause serous damage to your property.
As a quick recap, I always recommend to my customers that it’s important to control any potential water that may find its way to your footings by installing a proper drainage system, compact your excavation and control your surface ground water by sloping your property to the recommended building code in your area. Control and capture any roof or manmade surface area, including large patches of grass that are not able to naturally absorbed water like the original native soil. If you follow these basic steps you will ad years of value to your home.
Greg Truman
Urban Contracting
www.urbancontracting.ca
info@urbancontracting.ca
Kelowna 250-215-8006
Penticton 250-492-1147
Toll Free 877-290-8006
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