BC rain makes roof drainage a design-and-maintenance question, not merely a gutter accessory. Coordinate the water path while the roof is already being replaced.
Follow the water from ridge to grade
Rain first has to move across the roof covering, through valleys and around penetrations, into gutters or drains, then through downspouts and away from the building. A problem at any step can look like “a roof leak” even when the roofing material itself is not the only issue.
During reroofing, ask the contractor to identify obvious drainage bottlenecks: undersized or poorly located outlets, damaged gutters, dead valleys, roof areas dumping onto lower roofs and downspouts discharging where water can erode soil or collect beside the building.
The BC Building Code addresses roof drains and downspouts
The 2024 BC Building Code includes roof-drain provisions and states that where downspouts are provided and are not connected to a sewer, extensions are required to carry rainwater away in a way that prevents soil erosion. Local requirements and existing drainage systems can still vary.
That code language is not a substitute for a site-specific drainage plan. It is a reminder that the water path continues after the roof edge.
Valleys and low-slope transitions deserve their own scope
Valleys can carry a large amount of water during intense rain. Ask what underlayment, flashing or membrane detail the roofing system uses there, especially where several roof planes converge.
The same applies where a steeper roof meets a lower-slope porch or addition. The correct product may change as slope changes; a contractor should not automatically carry a steep-slope shingle system onto a section where the manufacturer does not permit it.
Decide whether gutter work is part of the roofing contract
Some roofers replace gutters; others do not. If gutters are staying, ask how they are protected and whether drip edge or eave work requires temporary removal. If they are being replaced, confirm size, outlets, downspout locations, leaf protection and discharge points.
A coordinated plan can prevent the common outcome where a new roof is installed but the old drainage problem remains untouched.
Sequence gutter work so the new roof is not damaged
If gutters are being replaced too, ask whether they come off before the roof, after the roof, or in coordinated sections. Eave metal, drip edge and gutter hangers can interact, and one crew should not have to undo another crew’s new work without a plan. The written estimate should identify which contractor owns each part of the edge detail.
After completion, walk the perimeter during or after a meaningful rain if it is safe to do so. Look for overflowing corners, water shooting past valleys, downspouts discharging against the foundation, or areas where the new roof changed how water reaches the gutter. Small drainage corrections are easier to address while the project is still fresh.
Questions to carry into the contractor conversation
- What part of the existing roof are you assuming can stay?
- Which conditions can change the price after tear-off?
- Which manufacturer details or code requirements affect this specific roof?
- Who is responsible for related work that is outside the roofing crew’s scope?
- How are unexpected changes documented and approved before extra work proceeds?
Those questions are intentionally broader than “what brand do you install?” They make the written scope easier to compare and reduce the chance that two estimates are pricing different jobs.
What HomeSelect can and cannot do
HomeSelect can help you organize the project, use a broad planning calculator and—where current coverage exists—seek one local contractor match. It does not inspect the roof, issue permits, design structural work, adjust insurance claims or guarantee a contractor’s estimate or workmanship.
Use the guide to prepare for a better conversation, then rely on the professionals responsible for the actual property to confirm the details that require inspection, design or regulatory interpretation.
Sources and verification
Official sources checked September 15, 2026. Codes, municipal requirements, product instructions and site conditions can change what applies to a specific project.
Use this with the BC roof planner
HomeSelect’s calculator is a broad planning tool, not a roofing quote. Use it to establish a range before deciding whether you want one local contractor conversation.