Exterior painting and siding

Ottawa gives you about five months to paint the outside of a house, and the quality of the result is decided almost entirely by what happens before the first coat. A bad exterior job looks fine in September and is peeling by the second spring.

Step one: assess the substrate. Wood siding, engineered wood, stucco, aluminium, vinyl, brick and fibre cement all behave differently and take different products. The painter should be looking for failed caulking, rot at the bottom of trim boards and around window sills, open joints where water gets behind, and any area where the existing paint is lifting rather than chalking. Rot is a carpentry repair, not a painting one, and it needs to be settled before a price is final.

Step two: washing. The whole surface is washed to remove dirt, pollen, chalked paint and any mildew, usually with a low-pressure wash and a cleaning solution rather than a high-pressure blast, which drives water behind siding and gouges soft wood. The house then has to dry, which in practice means a day or more of decent weather before anything goes on.

Step three: scraping, sanding and repair. Lifting paint is scraped back to a sound edge and feathered so the transition does not telegraph through. Failed caulking is cut out and replaced with an exterior-grade sealant at every joint between materials. Bare wood is spot-primed the same day it is exposed, because overnight moisture in bare wood causes the next round of peeling.

Step four: priming and finish coats. Bare wood, knots, tannin-prone species such as cedar and bare metal each need the right primer, and there is no universal one. Two finish coats is standard for a colour change or a heavily scraped surface. Application is usually spray-and-back-brush on siding and brush-and-roll on trim.

The Ottawa season, and why it is short. Most exterior latex needs surface and air temperatures above roughly 10 degrees Celsius during application and while it cures overnight, and some products need above 5 degrees. In practice that means mid-May to early October here, with the reliable window narrower than that at both ends. Painting in September is fine. Painting in the last week of October, when the overnight temperature dips below the product minimum after a warm afternoon, is how a coat fails to coalesce and starts shedding the following year. The other constraint is dew. A north-facing wall in late September can stay damp until eleven in the morning, which cuts the working day.

How long it takes. A typical two-storey Ottawa house with wood or engineered-wood siding is five to ten working days with a crew of two or three, spread over a longer calendar period because of weather. Trim, soffit and fascia only, with the siding left alone, is two to four days. Add days for extensive scraping, for a three-storey, or for anything that needs staging rather than ladders.

What it costs in Ottawa in 2026. Indicative ranges. Trim, soffits, fascia and doors only, on an average two-storey, commonly runs $3,500 to $7,000. A full exterior including wood siding is usually $8,000 to $20,000. Stucco tends to sit at the upper end because of the surface area and the amount of material a textured face drinks. What moves the number: how much scraping, whether staging is needed, the number of colours, access around the house, and whether rot repair is in scope. Insist that carpentry repairs are quoted as a separate line with an hourly rate and an allowance, because nobody can see behind a trim board until it comes off.

What makes an Ottawa house different. The freeze-thaw cycle here is punishing. Water gets into a hairline gap in the caulking in November, freezes, widens the gap, and does it again perhaps forty times over a winter. That is why caulking rather than paint is the part of an exterior job that fails first, and why replacing it properly is worth paying for. South and west elevations take the ultraviolet load and fade first, so a house often needs those two sides done a cycle earlier than the others. Much of the city also sits on Champlain Sea clay, which shrinks and swells seasonally (NRC, Geotechnical properties of Leda clay in the Ottawa area), and that movement shows up as recurring cracks where a porch, a garage or an addition meets the main house. Paint will not hold those closed. A flexible sealant will, for a while.

Product rules you are paying for. Canada regulates the volatile organic compound content of architectural coatings under SOR/2009-264, which sets limits across 53 categories, generally between 100 and 800 grams per litre depending on category, and binds manufacturers, importers and sellers rather than the painter (Environment and Climate Change Canada, VOC Concentration Limits for Architectural Coatings Regulations). The practical effect for you is that the high-solvent exterior oils of the past are gone from the shelf, and modern waterborne exterior products need their prep and their temperature window respected to perform. That is another reason the schedule matters here.

Who should do the work. There is no painter's licence in Ontario, so the credential to ask for is not a licence. Ask for proof of liability insurance, a WSIB clearance certificate (WSIB, Expanded Compulsory Coverage in Construction), and, because exterior work happens at height, confirmation that the crew has working-at-heights training and proper fall protection rather than a ladder and optimism. If carpentry repair is included, ask who is doing it.

What to ask before you hire. What washing method and what pressure. How much scraping is included, and what if there is more. All the caulking replaced, or spot repairs. Which primer on bare wood, and is it same-day. Two coats or one. What is your lowest application temperature. What voids the warranty. Is rot repair priced or an allowance.