Exterior painting is significantly more demanding than interior painting — and significantly more consequential when done poorly. A badly executed exterior paint job doesn’t just look bad: it can trap moisture behind the paint film, accelerating rot in wood substrates and causing mildew problems that spread into the wall assembly. In your country, where exterior surfaces face harsh freeze-thaw cycles, UV exposure, and temperature swings of 60°C or more across the year, preparation and product quality determine whether an exterior paint job lasts 3 years or 12.
“Exterior painting is mostly preparation. A professional exterior job on a wood-sided home involves power washing, drying time, scraping every loose edge, sanding transitions, spot-priming bare wood, caulking all the gaps, and then — only then — applying the finish coat. The painting itself is maybe 30% of the time. The rest is prep. A contractor who skips the prep can still make it look good on day one. You won’t know the difference until the second winter.”
— Carlos Mendez, certified painting contractor and member of the Painting and Decorating Contractors of America with 17 years of experience in residential interior and exterior painting across the Greater Toronto Area
Table of Contents
Questions About Surface Preparation
Will surfaces be power washed before painting?
Power washing removes dirt, chalk, mildew, and poorly adhered paint — all of which prevent new paint from bonding properly. Ask whether power washing is included, what pressure and technique will be used, and how long surfaces will be allowed to dry before painting begins (typically 24–48 hours minimum).
What a good answer looks like: Power washing included as standard, with a minimum drying period before paint application.
How will loose and peeling paint be addressed?
Painting over loosely adhered paint guarantees it will peel — with the new paint layer on top. All loose, bubbling, and peeling paint must be scraped and sanded before painting begins. Ask specifically how loose paint is being addressed and whether the crew will be hand-scraping or using heat guns or chemical strippers where needed.
What a good answer looks like: Full scraping of all loose paint, with sanding at edges to feather transitions.
How will bare wood be primed?
Any areas where paint has been removed down to bare wood must be primed before finish paint is applied. Paint applied directly to bare wood without primer will fail much faster. Ask specifically how bare wood areas will be primed and what primer product is being used.
What a good answer looks like: A specific oil-based or alkyd primer for bare wood, applied before finish coats.
Will caulking be replaced at trim, windows, and joints?
Gaps in caulking at window frames, door frames, trim joints, and siding transitions are water infiltration points. Before painting, these gaps should be filled with an exterior-grade paintable caulk. Ask whether recaulking is included in the quote and where.
What a good answer looks like: Recaulking of all gaps at trim, windows, and doors as standard — specified in the quote.
How will mildew be treated?
In shaded or damp areas, mildew on exterior surfaces must be treated with a mildewcide solution before painting. Paint applied over active mildew will fail quickly and the mildew will bleed through. Ask whether mildew treatment is part of the prep process.
Questions About Exterior Paint Products
What exterior paint product are you using?
Ask for the specific brand and product line. Quality exterior paint products for Canadian climates include Benjamin Moore Aura Exterior, Sherwin-Williams Emerald Exterior, and comparable premium lines. Ask what the product’s expected durability is and whether it carries a manufacturer’s durability warranty.
Is this product appropriate for my siding material?
Different siding materials require different products or application approaches:
Wood siding: Requires primer on bare areas, 100% acrylic latex finish. May benefit from oil-based primer on heavily weathered surfaces.
Fibre cement: Requires compatible primer and paint. James Hardie and other manufacturers have approved product lists — ask whether the proposed paint is on that list.
Vinyl siding: Not all paints adhere well to vinyl, and paint that’s too dark can cause vinyl to absorb excessive heat and warp. Ask whether the product is formulated for vinyl and whether the color chosen is within the safe lightness range for vinyl.
Stucco: Requires a breathable exterior paint that allows moisture vapor to pass through. Ask whether the product is appropriate for stucco and what masonry primer is being used.
What a good answer looks like: A specific product recommended for your siding material, with a clear explanation of why it’s appropriate.
Questions About Weather and Timing
What temperature and weather conditions do you require before painting?
Most exterior paints have minimum application temperature requirements — typically 10°C for latex paints, some allowing down to 4°C with extended dry times. Paint should not be applied in direct summer sun (which causes flash-drying and blistering), in high humidity or rain, or when surfaces are wet.
Ask specifically: what are the temperature and weather requirements for the product being used, and how does the contractor manage weather delays?
What a good answer looks like: Specific temperature minimums cited from the product’s technical data sheet, with a clear policy for weather delays.
What time of year is best for exterior painting?
In most regions, the exterior painting season runs from late May through September — avoiding the extremes of summer heat and the cold of late fall. Early morning application in summer avoids painting in direct afternoon sun. Ask whether the proposed schedule aligns with optimal conditions for the product and your climate.
How long before rain can fall on freshly painted surfaces?
Ask specifically how long each coat of paint needs before rain can fall on it without damage. This varies by product — most modern exterior latex paints are rain-safe within 1–4 hours of application.
Questions About Lead Paint
If my home was built before 1978, how will you handle potential lead paint?
Homes built before 1978 may have lead-based paint on exterior surfaces. Sanding or scraping lead paint creates hazardous dust. Ask whether the contractor has assessed the risk of lead paint and what precautions they take — including use of HEPA vacuums, wet scraping methods, and proper disposal of debris.
What a good answer looks like: A protocol for lead paint that includes testing if unknown, and proper precautions if lead is present.
Related Questions
- Questions to Ask a Painter Before You Hire One
- Questions to Ask a Painter About Paint Products
- Questions to Ask When Getting a Painting Quote
- How Much Does It Cost to Paint a House ?
- How Do I Know If My Home Needs to Be Repainted?
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