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Coatings

Written for Canada. Plans are metric, but many crews and suppliers work in feet and inches, so this site gives both: millimetres and metres, with feet and inches beside them. Codes are the National Building Code of Canada 2020 (NBC 2020) Part 9 as your province adopts it. A number marked Confirm has not been checked against every province, so check it with your own authority before you act on it.

Reviewed by a working tradesman with 17+ years in the field.

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Coatings are quick and cover irregular surfaces, but their performance depends on the thickness you actually apply.

I am a:

Tap your level and the boxes below open to the advice for you. Remembered on this device.

What it isLiquid products brushed, rolled or sprayed onto the wall, as dampproofing or as a layer over a membrane.
Your jobPrepare the wall, apply the coats and thickness the maker specifies, and seal the footing joint.
The hard ruleA dampproofing coating is not a waterproofing system. Where water pressure is expected, get a designed system.
The checkA wet-film gauge reading and a dated photo for each coat, before backfill.

By the end you can

  • Choose between coating types for the exposure.
  • Prepare a wall and apply coats at the thickness the maker specifies.
  • Check wet film thickness with a gauge.
  • Check that the coating works with the mat, membrane and insulation that touch it.
Stop and read

Read the safety data sheet for every coating and primer (WHMIS). Many are solvent-based and give off vapours that are harmful in closed or low areas such as a deep excavation. Use the gloves, eye protection, respirator and ventilation the sheet calls for, and keep ignition sources away from solvent products.

You are working in a hole beside a tall wall. Treat any excavation 1.2 m (4 ft) or deeper as a trench, and follow the Trench Safety page and your provincial OHS regulator.

The big idea

Coatings are quick and cover irregular surfaces, but how well they work depends on the thickness you actually put on. They can be the dampproofing itself, or a layer over a membrane or bare concrete.

Part 9 requires the outside of a below-ground wall to be dampproofed where the exterior ground is higher than the inside ground level (9.13.2.1). It lists the accepted materials, and a bituminous application has to follow CAN/CGSB-37.3-M (9.13.2.3). I read this in the Vancouver Building Bylaw 2014, so check your province's edition.

Types of coating

  • Asphalt-based (bituminous) coatings: the traditional dampproofing. Low cost, but they do not bridge cracks, and the number of coats matters.
  • Polymer-modified coatings: more flexible, with better adhesion.
  • Rubberized and elastomeric coatings: bridge small cracks and move with the wall.
  • Spray or roll-on: spray is fast over large areas, and roll-on suits small areas and repairs.
Dampproofing or waterproofing coating?

A coating sold for dampproofing is not a waterproofing system. Check the product data for the exposure it is rated for, its required film thickness, and whether it is accepted under Section 9.13 as adopted in your province and by your inspector. A building-science article says asphaltic coatings cannot block water under pressure.

Surface preparation

  • Clean the wall of dirt, dust, form oil and loose material.
  • Seal the form-tie holes (9.13.2.4). Patch cracks, holes and voids.
  • Let the concrete cure as the maker requires. One maker's sheet allows spray on poured concrete as soon as the forms are off, so the rule is product-specific.
  • Apply any primer first, and let it dry.

Application

  1. Mark the height Mark the grade line and the coating height with a chalk line.
  2. Seal the joint first Put a heavy bead of sealant, or extra coating, over the footing-to-wall joint, so it is thick and continuous.
  3. Coat evenly Coat from the footing up to the grade line, in the number of coats and the thickness the maker specifies. Thin coats are the most common failure.
  4. Check thickness Press the wet-film gauge into the wet coating in several places, and photograph each reading.
  5. Let it cure Let each coat cure before the next, and before the drainage mat or backfill. Cure times vary a lot by product, so follow the label.
  6. Protect it Protect fresh coatings from rain, and from backfill damage once buried.

Thickness and quantity

Wet film thickness is dry film thickness divided by the volume solids of the product. A product specified at 15 mil (0.38 mm) dry and 60 percent solids needs 15 ÷ 0.60 = 25 mil (0.64 mm) wet. The 60 percent is made up. Use the number on your data sheet.

One maker's data sheet for an asphalt emulsion gives 60 to 65 ft² per US gallon for 15 mil dry. Applied to a 930 ft² (86.4 m²) wall, that is about 14 to 16 US gallons (54 to 59 L). Add margin for waste. That is one product, so use your own product's coverage rate.

Compatibility

  • Check that the coating works with the membrane, drainage mat and any insulation or adhesive that touches it.
  • Solvent-based products can attack foam insulation and some membranes. The data sheet I read did not address foam, so ask the maker.
  • Follow the maker's recommended combinations.

Common mistakes

  • Coating a wet or dirty wall
  • Too thin
  • Skipping the joint
  • Not letting it cure
  • Damage from backfill
  • Using a dampproofing coating where water pressure is expected
Pro note

Measure the wet film thickness. If you cannot show the thickness, you cannot say the wall is protected.

Weather note

Cold slows curing, and some products have a minimum application temperature, so check the label. Hot sun can skin the surface before it cures. Rain washes uncured coatings off.

What the inspector looks at

Coverage, thickness, the footing joint, and protection before backfill.

✅ Check yourselfTap a question
A product is spec'd at 15 mil (0.38 mm) dry film and is 60 percent solids by volume. What wet film thickness do you check with the gauge?
Wet film = dry film ÷ solids = 15 ÷ 0.60 = 25 mil (0.64 mm). The 60 percent is made up. Use the figure on your product's data sheet.
One maker's sheet gives 60 to 65 ft² per US gallon for 15 mil dry. How much for a 930 ft² (86.4 m²) wall?
930 ÷ 65 = 14.3 gal and 930 ÷ 60 = 15.5 gal, so about 14 to 16 US gallons (54 to 59 L). That is one product's figure. Use your own product's data sheet and add a margin for waste.
What is the difference between a dampproofing coating and a waterproofing system?
Dampproofing resists moisture from damp soil. Waterproofing resists water under pressure. A coating sold for dampproofing does not stop pressure, so where pressure is expected you need a designed waterproofing system.
Where does Part 9 say dampproofing goes on a poured concrete wall?
Over the concrete below ground level (9.13.2.5), after the form-tie holes are sealed (9.13.2.4).
Why is the footing-to-wall joint treated separately?
It is where water runs along at footing level. Seal it with sealant and extra coating, so the joint is thick and continuous.
The label says it dries in 2 hours, but rain is forecast tonight. What do you do?
Do not rely on a quick label time. Stop if rain will reach an uncured coat, because rain washes uncured coatings off. Check the label's own rain and temperature limits.
🧰 Gear for this stepMust-haveRent itNice to have
  • Must-haveLayout and measuring: tape measure and chalk line to mark the grade line and coating height
  • Must-haveSurface prep:
  • Must-haveApplying (hand tools):
  • Rent itApplying (sprayer): an airless sprayer for large areas
  • Must-haveMixing and checking:
  • Must-haveRecords: a phone or camera for dated photos of each coat
  • Must-havePPE: hard hat (CSA Z94.1), eye protection (CSA Z94.3), green-triangle boots (CSA Z195), chemical-resistant gloves, coveralls, and a respirator (CSA Z94.4) with cartridges matched to the safety data sheet
👷 Who can do thisTap your level
Home DIY
A capable owner can brush or roll a dampproofing coating on a shallow, dry, clean wall by following the label. Treat 1.2 m (4 ft) as a no-entry line, do not judge sloping or shoring yourself, and do not dig beside an existing foundation. Do not work in a closed or low area with solvent vapours. Hire a pro where water pressure is expected, because a dampproofing coating will not stop it.
Laborer or helper
Help with prep, cleanup and moving product as directed. Never enter an excavation 1.2 m (4 ft) or deeper, and stay out of closed or low areas with solvent vapours. Read the safety data sheet before you handle any product.
1st-year apprentice
Under supervision, prep the wall, mix and apply coats, and measure wet film thickness. Learn first the maker's coat count, cure times and temperature limits, and how to read the safety data sheet.
Apprentice, 2nd to 4th year
Prep the wall, mix and apply coats, and measure wet film thickness under supervision. Learn the coat count and cure times. Stay out of closed areas with vapours. Tell your journeyperson if the wall is wet or rain is coming.
Journeyperson
You own the choice of coating for the exposure, the thickness and the joint detail, and compatibility with membranes, mat and foam insulation. Stop-work triggers: the wall is wet or frosted, the temperature is outside the label limit, or rain is forecast before the coat cures.
Lead hand or foreman
Check the wall, temperature and forecast before the first coat. Enforce the stop-work triggers: wet or frosted wall, temperature outside the label limit, or rain before cure. Verify wet film readings, respirator fit and ventilation. Keep the 1.2 m (4 ft) no-entry line.
Contractor or business owner
Price by coats and area, and record wet and dry film checks with photos. Insure and train for solvent products (WHMIS, respirator fit). Subcontract where the design is waterproofing. Thin coats are the common failure, so record the wet film checks. Ask your lawyer or insurer who carries the liability.
Starting a new business
Learn the label limits and WHMIS before you quote coatings. Subcontract the job where the design is waterproofing. Record wet and dry film checks. Confirm respirator, WHMIS and excavation rules with your provincial regulator, and liability with your insurer and lawyer.
By Province:

The technique is the same across Canada. What changes is the code edition, which coatings are accepted, and when the inspector wants to see them. I read Section 9.13 as printed in the Vancouver Building Bylaw 2014, so check the clause numbers against your province's edition and ask your local building department which inspection stage covers dampproofing.

See Canada by Province for the full comparison.

Sources:

Last reviewed October 2026. General information, not engineering or legal advice.

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