Drainage Solutions
Effective drainage is key to a dry crawlspace. We design systems that move water away from your home before it can cause damage.
Drainage problems in crawlspaces have two distinct origins: water that arrives from outside (surface runoff, failed exterior drainage, high water table) and water that condenses from the air inside the crawlspace onto cooler surfaces. The solutions for each are different, and correctly diagnosing which problem you have — or which combination — is the critical first step. Applying interior drainage solutions to an exterior water problem provides partial relief at best; addressing the exterior source is far more effective and usually less disruptive.
Exterior drainage improvements include grading the soil around the foundation so the ground slopes away from the house at a minimum of six inches over the first ten horizontal feet, extending downspout leaders far enough from the foundation (ideally into underground drains that outlet well away from the home), and where necessary, installing French drain systems in the yard to intercept groundwater before it reaches the foundation. Clay-heavy soils common throughout Surrey and Delta hold water at the surface and channel it laterally toward the lowest point — often a foundation wall — rather than allowing it to percolate downward. This is a manageable problem with the right grading and drainage, but it requires understanding the site-specific water flow patterns.
Interior drainage systems — perimeter drain tile installed inside the crawlspace along the base of the stem wall — are the right solution when exterior work is impractical (due to finished landscaping, hardscaping, or very tight site conditions) or when the primary issue is groundwater rising from below rather than surface water entering through the wall. Interior drain tile channels water to a sump pit where a pump removes it. This approach does not stop water from entering the foundation, but it manages it effectively once it does.
Downspout management is an area homeowners frequently underestimate. A typical residential roof sheds enormous volumes of water during a moderate Fraser Valley rain event, and all of it is concentrated at four to six downspout outlets. If those outlets discharge into splash blocks immediately adjacent to the foundation — or worse, into clogged or broken underground leaders that overflow next to the footing — they become the primary driver of crawlspace water intrusion. Extending downspouts and routing them to proper outlets is one of the highest-return drainage improvements available.
A complete drainage assessment from our team covers the exterior grading and drainage outlet conditions, the condition of gutters and downspout leaders, any visible water staining or efflorescence on the interior stem walls (which indicates where water is entering), the current drainage infrastructure inside the crawlspace, and the soil conditions and water table depth during the wet season. From there we design a system that addresses the actual water pathways specific to your property.