How do I keep painted wood window frames from cracking and peeling through multiple NB winters without repainting every two years?

The key to long-lasting painted window frames in New Brunswick is using 100% acrylic latex paint over properly prepared surfaces, combined with annual caulking maintenance and moisture control. Most window frame paint failure happens because rigid oil-based paints can't flex with NB's 100+ freeze-thaw cycles per year, or because moisture gets behind the paint through failed caulk joints.

Choose the Right Paint System

Window frames take the worst beating of any exterior surface in NB — they're fully exposed to weather, experience constant thermal expansion and contraction, and are prime spots for moisture infiltration. Use a premium 100% acrylic latex exterior paint (Benjamin Moore Aura Exterior, Sherwin-Williams Duration Exterior, or Dulux Diamond Exterior) in satin or semi-gloss sheen. These paints remain flexible at low temperatures and can handle the expansion and contraction without cracking. Avoid oil-based or alkyd paints on window frames — they become brittle in cold weather and crack under freeze-thaw stress.

Always use a high-quality bonding primer on bare wood or previously painted surfaces that are chalky or glossy. For windows with multiple paint layers or staining issues, use a stain-blocking primer like Zinsser Cover Stain or Benjamin Moore Fresh Start.

Surface Preparation is Critical

Scrape all loose and peeling paint down to solid, well-adhered coating or bare wood. Sand glossy surfaces to provide tooth for the new paint. Fill nail holes and small gaps with exterior wood filler, and sand smooth once dry. The most important step: remove all old caulk from around the window frame where it meets the siding, trim, and sill. Old, cracked caulk is the number one cause of moisture infiltration that leads to paint failure from behind.

Clean the frames thoroughly with TSP or a degreasing cleaner to remove dirt, oxidation, and any mildew. Rinse well and allow to dry completely — wood moisture content should be below 15% before painting.

Moisture Control and Caulking

After priming and painting, apply a high-quality exterior acrylic caulk (like DAP Dynaflex 230 or Tremco Dymonic) to all joints where the window frame meets siding, trim, brick, or stone. This flexible caulk moves with thermal expansion and keeps water out. Plan to inspect and touch up caulking annually — this 30-minute maintenance task in late fall can add 2-3 years to your paint job.

Check that your windows have proper flashing and that water drains away from the sill. Standing water on window sills soaks into the wood and pushes paint off from behind. If you have older windows without drip caps or proper flashing, consider having these installed by a carpenter before repainting.

Timing and Application in NB Climate

Paint window frames during NB's prime exterior season (June through early September) when humidity is manageable and temperatures are consistently above 15°C. Avoid painting in direct hot sun — the rapid drying can cause brush marks and poor adhesion. Early morning or late afternoon application works best.

Apply thin, even coats rather than trying to cover in one heavy coat. Two thin coats of quality paint will outlast one thick coat by years. Allow the recommended recoat time between coats — in NB's humid summers, this might be 4-6 hours instead of the 2-4 hours listed on the can.

When to Call a Professional

If your windows are original to a pre-1978 home, they likely have lead paint. Window frames were commonly painted with lead-based paint because of its durability. Never sand, scrape, or disturb suspected lead paint yourself — hire a professional with lead-safe work practices, especially if you have children in the home. Professional painters also have the spray equipment to achieve the smoothest possible finish on window frames, which helps water run off rather than pooling in brush marks.

With proper preparation, quality materials, and annual caulk maintenance, you should get 5-7 years from a professional window frame paint job in NB's climate, and 4-5 years from a careful DIY job.