Should I encapsulate the crawl space?

Not as an answer to water that is arriving through the wall. Sealing a space that is still taking on groundwater traps the problem rather than solving it. Deal with grading and drainage first, then decide about the ground cover on its own merits — which is also the order the Code puts them in.

There is standing water under my house right now. Is that an emergency?

It is urgent rather than an emergency, unless it is near electrical equipment or a heating appliance, in which case stay out and call for the power to be dealt with first. Otherwise photograph it while it is there — that photo is worth more to a contractor than any description you can give in March.

My crawl space smells musty but looks dry. What is that?

Usually evaporation from ground that is covered poorly or not at all, sometimes combined with vents that no longer breathe. That is a ground cover and ventilation question rather than a drainage one, which is why it is worth separating the two before you buy anything.

Does a crawl space house need a different kind of perimeter drain?

No. The Code sends crawl space drainage back to the same section that governs every other foundation drain in the province, so pipe size, depth below the slab or ground cover, stone, and where the water is allowed to go are all the same.

My crawl space is wet. Is that the perimeter drain, and what is actually required down there?

Wet crawl space, or just a damp one?

Direct answer · reviewed 2026-09-22

There are two different problems under a house and they get sold as one. Water arriving — standing water, a wet patch after a storm, damp along one wall — is a drainage problem, and the Code says so directly: Section 9.18 sends crawl space drainage straight back to the same section that governs a basement drain. Moisture leaving the soil is a different thing. Bare or badly covered ground evaporates water into the space all year, and no amount of drain work will stop that, because the water was never arriving from outside. Before you buy either fix, find out which one you have. It is usually visible, and the test costs nothing.

Conditions and exceptions

Standing water after rain, or a wet band along one elevation, points at drainage. Uniformly damp ground with dry walls usually does not.
The two can and often do occur together on an older Greater Victoria house.
What the Code asks for down there changes completely depending on whether the space counts as heated, which is a technical definition rather than a question of whether it feels warm.

Drain problem assessment

Local evidence

Every figure below is quoted from the source shown or is our labelled estimate. Verified dates are the day we last checked the source; a figure whose check is overdue is withheld rather than shown.

What the Code requires about water getting into a crawl space: Except where it can be shown to be unnecessary, the ingress of water into a crawl space shall be controlled by grading or drainage; Grading is listed first and is the cheaper of the two · The same 'unless shown to be unnecessary' wording appears in the foundation drainage requirement; Province of British Columbia (BC Codes) · quoted · verified 2026-09-22
Is a crawl space drain a different system from a basement drain?: No — the Code sends crawl spaces back to the same section: drainage of foundation walls shall conform to Article 9.14.2.1, and drains shall conform to Section 9.14; So pipe size, depth, stone cover and discharge rules are identical to a basement house · Drainage of the ground cover itself is sent to Subsection 9.16.3 instead; Province of British Columbia (BC Codes) · quoted · verified 2026-09-22
Ground cover required in an unheated crawl space: Not less than 50 mm of asphalt, 100 mm of 15 MPa Portland cement concrete, Type S roll roofing, or 0.10 mm polyethylene, with sheet joints lapped at least 100 mm and weighted down; Four materials, all equally acceptable under the Code; Province of British Columbia (BC Codes) · quoted · verified 2026-09-22
Ground cover required in a heated crawl space: Polyethylene sheet of not less than 0.15 mm installed as part of an air barrier system, with joints lapped at least 300 mm, sealed and weighted or covered with 50 mm of concrete, the perimeter sealed to the foundation wall and every penetration sealed against air leakage; A crawl space counts as heated if it is a hot air plenum, carries unsealed heating ducts, or is not separated from heated space (Article 9.18.1.3) · This is a markedly more demanding spec than the unheated one, and it is the one most often done to a lower standard; Province of British Columbia (BC Codes) · quoted · verified 2026-09-22
Ventilation required in an unheated crawl space: Where it is ventilated naturally, not less than 0.1 square metres of unobstructed vent area for every 50 square metres of floor area, uniformly distributed on opposite sides of the building; Vents must also be designed to keep out snow, rain and insects · Blocked or buried vents are common on older Greater Victoria houses where garden beds have risen over the years; Province of British Columbia (BC Codes) · quoted · verified 2026-09-22

Telling arriving water from leaving water

The Code's own sentence about this is short and worth reading before anyone quotes you anything. Except where it can be shown to be unnecessary, the ingress of water into a crawl space shall be controlled by grading or drainage Grading comes first in that sentence for a reason: on a lot of Greater Victoria lots the ground has slowly risen against the house over decades of garden beds and mulch, and the cheapest fix is to take it back down.

And when the water is arriving rather than evaporating, there is no separate crawl space drainage system to learn about. No — the Code sends crawl spaces back to the same section: drainage of foundation walls shall conform to Article 9.14.2.1, and drains shall conform to Section 9.14 So everything on this site about pipe, stone, depth and discharge applies to your house exactly as it would to a basement.

Go under during a heavy storm, not on a dry day in July. The difference between the two problems is only visible while it is raining.
Look for where it is wet rather than how wet it is. A band along one wall is drainage; even dampness everywhere is usually the ground.
Check whether the ground cover is intact, lapped and weighted, or pushed aside by whoever last crawled through.
Find the vents from outside and check that soil, decking or a garden bed has not buried them.
Only then decide whether you are buying drainage work, ground cover, or both.

What has to be on the ground

The Code sets two quite different standards, and the one that applies to you depends on a definition rather than on how the space feels. A crawl space counts as heated if it is used as a hot air plenum, if it carries heating ducts that are not sealed and insulated, or if it is not separated from the heated space above.

For an unheated space: Not less than 50 mm of asphalt, 100 mm of 15 MPa Portland cement concrete, Type S roll roofing, or 0.10 mm polyethylene, with sheet joints lapped at least 100 mm and weighted down

For a heated one the bar is much higher. Polyethylene sheet of not less than 0.15 mm installed as part of an air barrier system, with joints lapped at least 300 mm, sealed and weighted or covered with 50 mm of concrete, the perimeter sealed to the foundation wall and every penetration sealed against air leakage

That second spec is the one most often met loosely. Sheet laid down and left unsealed at the perimeter, lapped a hand's width instead of 300 mm, cut around a post and never taped — each of those is a small thing, and together they are the difference between a vapour barrier and a tarp.

Heated and unheated crawl spaces are held to different standards
	Unheated	Heated
Ground cover	Asphalt, concrete, roll roofing or 0.10 mm poly	0.15 mm poly, part of an air barrier system
Joint laps	At least 100 mm, weighted down	At least 300 mm, sealed and weighted or covered in concrete
Perimeter	Not specified	Sealed to the foundation wall
Penetrations	Not specified	Sealed against air leakage
Ventilation	Natural or mechanical, to the outside	Sent to Section 9.32 instead

Vents, and why yours may have disappeared

For an unheated crawl space ventilated naturally, the Code puts a number on it. Where it is ventilated naturally, not less than 0.1 square metres of unobstructed vent area for every 50 square metres of floor area, uniformly distributed on opposite sides of the building

On a house built in the fifties or sixties, the vents were almost certainly right when it was built. What changed is the outside: a deck went over them, a bed was built up against the wall, a previous owner stuffed them with insulation one cold winter and nobody took it out. Walking the perimeter and counting the vents you can actually see is a five-minute job and is a common explanation for a crawl space that has become damp without anything obviously breaking.

Two things a contractor cannot simply assert

Both of these come from Appeal Board decisions, which are how disputes between homeowners and building officials actually get settled in this province.

The first is about materials. No — the Appeal Board held that polyethylene ground cover is acceptable in a crawl space and that the choice of which permitted material to use belongs to the owner or builder, not the building official The Board overturned a municipality that had a standing policy of accepting only concrete. If someone tells you poly is not allowed here, that is a preference being described as a rule.

The second is about the drain itself, and it cuts the other way — against homeowners being told their whole system is defective. Not necessarily — the Appeal Board found it is not necessary for the drain pipe to be at the bottom of the wall or at the level of the footing, provided it is below the level of the floor slab On a stepped Greater Victoria lot, where one section of wall runs deeper than the rest, a pipe that is not down at footing level along that section is not automatically wrong.

Questions homeowners ask

Should I encapsulate the crawl space?: Not as an answer to water that is arriving through the wall. Sealing a space that is still taking on groundwater traps the problem rather than solving it. Deal with grading and drainage first, then decide about the ground cover on its own merits — which is also the order the Code puts them in.
There is standing water under my house right now. Is that an emergency?: It is urgent rather than an emergency, unless it is near electrical equipment or a heating appliance, in which case stay out and call for the power to be dealt with first. Otherwise photograph it while it is there — that photo is worth more to a contractor than any description you can give in March.
My crawl space smells musty but looks dry. What is that?: Usually evaporation from ground that is covered poorly or not at all, sometimes combined with vents that no longer breathe. That is a ground cover and ventilation question rather than a drainage one, which is why it is worth separating the two before you buy anything.
Does a crawl space house need a different kind of perimeter drain?: No. The Code sends crawl space drainage back to the same section that governs every other foundation drain in the province, so pipe size, depth below the slab or ground cover, stone, and where the water is allowed to go are all the same.

Your next step

The tool asks what you saw and when, which is what separates arriving water from evaporation.

Work out which of the two problems you have

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Sources

British Columbia Building Code 2018, Division B, Section 9.18 — Crawl Spaces — Province of British Columbia (BC Codes), accessed 2026-09-22
British Columbia Building Code 2018, Division B, Section 9.14 — Drainage — Province of British Columbia (BC Codes), accessed 2026-09-22
BCAB #1373 — Ground cover in a crawl space (16 December 1994) — Building Code Appeal Board, Province of British Columbia, accessed 2026-09-22
BCAB #1345 — Location of foundation perimeter drain pipe (18 April 1994) — Building Code Appeal Board, Province of British Columbia, accessed 2026-09-22

Code and municipal requirements are quoted from the sources above; price ranges are what named local companies publish, and the companies that publish them sell the work. Nothing here is a diagnosis of a particular house: only a camera in your own drain can tell you what is wrong with it. Report a correction.