Flat surfaces first
Walls shed water. Floors, steps, sills and the tops of railings hold it. On most painted houses, the horizontal and walked-on surfaces are where the finish gives out first, and they're the part of an exterior bid that's easiest to underprice. This page is about them.
About the weather figures
Every weather figure here comes from NOAA's engineering weather data for the Johnstown/Cambria station, about 6 miles from Johnstown. They describe that station's record. Conditions at your address can differ, and nothing below assumes otherwise.
Freeze-thaw on a porch floor
NOAA's data for the Johnstown/Cambria station, about 6 miles from Johnstown, lists about 53 freeze-thaw cycles in an average year. On a level surface, each one works on water that has soaked into the wood or pooled in a joint.
What that looks like on a porch:
- paint lifting first along board ends and at the gaps between boards;
- grey, bare wood in the traffic path where foot wear has thinned the film;
- soft spots near the steps or under a downspout outlet, where water collects.
A paint coat can't hold on rotting or saturated wood. Boards that are soft should be replaced, and the rest should be scraped, dried and spot-primed before a floor-grade porch enamel or deck coating goes on. Ask whether the product the painter quotes is rated for foot traffic.
Steps and railings
Stair treads take the same wear as the floor, plus the scuffing of every arrival. Railings are mostly vertical, but their caps and the tops of balusters catch rain and stay wet. On many houses those caps fail before anything else on the porch. A thorough painter scrapes and primes the cap, looks for gaps where balusters meet the rails, and asks whether you want an anti-slip additive on the steps.
Sills and the bottom of trim
Window sills slope to shed water, but only if their paint film is whole. Once the film cracks, water sits in the crack and the wood darkens and softens. The bottom ends of door casings, where they meet a threshold or porch floor, fail the same way. Ask the painter to probe these spots during the estimate and say what they'll do with soft wood they find.
Rain rate and drying time
The station data also lists a 100-year rainfall rate of 2.6 inches per hour, a figure engineers use for rare storms. For painting, the useful point is simpler: a level surface coated in the afternoon can be ruined by a passing shower that would barely mark a wall. Floors and steps need a dry forecast and enough hours before the next rain for the coating to set.
For the drying side, NOAA counts about 69 hours a year with the wet-bulb temperature above 73°F and about 684 hours above 67°F at the same station. On the muggier days, porch enamels and oil-based coatings can stay tacky for longer than their labels suggest, so it helps to plan when the porch can go back into use.
Who does the carpentry
Replacing a porch board, a stair tread or a section of sill is carpentry. Some painters do it themselves, some bring in someone else, and some leave it to you. Get the answer in writing. Our deck and fence staining page covers coatings for walking surfaces in more detail.
Pennsylvania's home improvement law
The Pennsylvania Office of Attorney General says painting is on the Home Improvement Consumer Protection Act's list of home improvements. The fact card sets out who must register.
Questions for the walk-through
- Which boards, treads or sills are soft enough to replace?
- What coating will go on the porch floor and steps, and is it made for foot traffic?
- How long before we can walk on it, and what weather do you need?
- Will you prime the railing caps and baluster tops separately?