by Larry Clay
I met with homeowners this week whose home had water coming into their basement. They were stressed from the potential costs and inconvenience to their life. Remediation after the fact would be exorbitant.
This home was typical of many homes where the builder’s only goal was to pass inspection, build to code and make money. Building to code is the lowest level of construction you can legally build in Canada. This is a minimum standard.
8 Steps to Success
Below are eight procedures completed on the exterior of a home to prevent water from entering the basement. Ideally, this is done during construction.
- The footings must be placed on a healthy bed of free draining crushed rock. This allows for ground water to make its way to the drainage piping around the perimeter of the foundation. Secondly, it keeps water from wicking up to the concrete foundation.
- Use superior PVC perforated drainage pipes. They cost a little more but in the event of a blockage, they can be snaked and cleaned. Big O drainage piping should never be used. In fact, some municipalities have banned the use of Big O drainage piping.
- The foundation is sprayed with a dampproofing asphalt. A thicker water proofing spray is better. A superseal drainage mat is placed over the asphalt spray. Backfill material will butt up to the drainage mat. In the event water gets past the dimpled membrane mat it will flow freely down to the drainage pipes.
- For builders, it is cheapest to backfill with the native material from the site. This is often unsuitable material. Material that is not free draining will not allow water to flow down to the drainpipes sitting at the bottom of the foundation. Often we need to import free draining material like crushed rock or gravel.
- Lot grading must take water away from the house.
- Gutter downpipes should never deposit water at the foundation. You may run the downpipes into solid PVC pipes and take the rainwater into the city storm if allowed by your city. Alternatively, you may run the downpipes into a large rock pit located away from the foundation. If site conditions allow, you may be able to run down pipes into a ditch or gulley if slope allows.
- Driveways and sidewalks must not guide water towards the house. In the event the house is lower than the road, trench drains must be installed to transfer water away from the house.
- Landscaping must not impede the flow of water away from the house.
Doing It Right From The Start
While a house is under construction, there are a number of upgrades that will potentially save thousands of dollars in the event of a wet basement. Penny wise, pound-foolish. Most of us cannot afford the maintenance and remediation costs of a poorly built house. Smart and strategic spending on the construction of your house will ensure a healthy, efficient and solid home built for the generations.