Heat is a scheduling problem, not just a comfort one
Most advice about weather and paint is about cold. In Reading, the figure worth starting with is the hot one. NOAA's climate normals for the Reading Spaatz Field station count 23.8 days a year reaching 90°F or more, along with 1,055.8 cooling degree days a year. Those are the station's 1991-2020 normals, not readings from your block, but they tell you the summer calendar will include stretches when painting in full sun is a poor idea.
What a hot wall does to fresh paint
Paint needs a little time wet on the surface to level out and bond. A wall baking in afternoon sun can take that time away.
- Lap marks. When the paint dries almost as fast as it's rolled, the edge of one pass is already set when the next overlaps it, and the overlap shows as a stripe.
- Poor flow. Brush marks that would normally level out stay in the film.
- Blistering. Dark colors and dark siding in direct sun can get hot enough that solvent or moisture trapped under a fresh film pushes it up in small bubbles.
- Weak bond on bare spots. Primer on hot, dry wood can soak in too fast to do its job.
Most exterior paint labels give a maximum surface temperature as well as a minimum. Ask the painter what the product they're quoting allows.
How good crews work around the heat
The usual fix is to follow the shade. A crew starts on the west side in the morning, moves around the house as the sun does, and leaves the east side for afternoon. On the hottest days some crews stop by early afternoon, or switch to prep work such as scraping, caulking and masking, and come back to the coating when the walls cool.
None of that is a delay to be annoyed about. A painter who tells you they'd rather not roll the south wall at two o'clock in July is protecting the finish you're paying for. See our exterior painting page for the full order of a house repaint.
Inside, heat matters too
Summer interior work has its own wrinkle. With windows shut and air conditioning running, rooms stay cool, but paint still needs fresh air to dry and to clear its smell. With windows open on a hot, damp day, the coat dries slowly and stays soft longer. Ask how the crew plans to ventilate and how long before furniture goes back.
Older paint and the federal rule
If the house was built before 1978, the layers on its walls and trim may include lead-based paint. The U.S. EPA's Renovation, Repair and Painting Rule says anyone paid to do work that disturbs paint in homes, childcare facilities and preschools built before 1978 must hold RRP certification, firms included, even sole proprietorships, and their workers must be trained in lead-safe work practices. Scraping and sanding are exactly the kinds of work that disturb paint.
It's reasonable to ask the painter whether their firm holds RRP certification, and how they'll contain dust and chips on your job. We don't check that for you.
Pennsylvania's home improvement law
Pennsylvania's Office of Attorney General says the Home Improvement Consumer Protection Act's list of home improvements includes painting; the fact card below gives the registration rule as that office states it.
Before you sign
- Which walls will you paint at which time of day, and why?
- What are the minimum and maximum surface temperatures on your products?
- What happens to the schedule during a heat wave?
- How will you keep dust and chips contained if the old paint is disturbed?
- How many coats go on each surface, and with what?
For more on comparing proposals, read our pricing guide.