Remodelers aren't called upon to build as many foundations as new home builders, but it's still a skill at which they need to be proficient. Any foundation remodelers dig for an addition, shore up for a house, or reinforce in order to add on to a house must, obviously, be properly built and be watertight.
Proper drainage at the footer is key to a successful foundation. The best place to put drainpipe is along the footer, so that rising water can be carried away before it has a chance to climb and increase hydrostatic pressure against the wall. Remember to lay the pipe in a way that resists dips and sags that collect silt and eventually clog the drain. A few years ago, I discovered Form-A-Drain, a product manufactured from PVC material. Several rows of slits puncture the 12-foot rectangular sections, allowing water to enter. Couplings, corners, steel grade stakes, and drainage outlets create a complete drainage system. But Form-A-Drain's unique feature is that it doubles as a footer form: Set the forms; pour the concrete. Not only do you have the footer for a foundation but you also have a properly located drainage system. Form-A-Drain also can vent radon gas.
You'll pay more for Form-A-Drain than the 2x's used to form the typical footer along with perforated round drainage pipe, but this cost can be offset with reduced labor costs: One product does two jobs. Don't forget to cover the drainpipe with washed stone and with a filter fabric to keep silt from clogging the drain.
Directing the Water
Sometimes getting roof runoff water down to the drainpipe can be challenging, particularly when soils surrounding the foundation have a high clay content or where there's an exceptionally high seasonal water table. You'll want to create a drainage layer at the foundation wall surface to encourage water to go down to the perimeter drain.
Todd LaBarge, a Dennisport, Mass., contractor, accomplishes this using Sure-Drain, a flexible plastic sheet with dimples and an attached filter fabric. Hold the dimpled sheet against the foundation while backfilling to maintain the sheet's effectiveness.
If you want to incorporate insulation into your drainage mat, Koch Waterproofing offers the Tuff-N-Dri system -- an Owens Corning fiberglass foundation board adhered to a spray-applied waterproofing membrane. Koch rounds out its system with DrainStar, a rigid polymer with egg-crate shaped cones and an attached filter fabric, which the manufacturer claims replaces traditional drainpipe and gravel systems.
Whichever system you decide on, you can ease the pain of an expensive callback by installing a proper drain.
--Lee McGinley, CR, a Big 50 remodeler, has written for the Journal of Light Construction. He lives in Addison, Vt.