Wood rot in St. Petersburg homes: where it hides and when to fix it

About half of St. Pete's housing was built before 1970, and Florida humidity is hard on wood. Where rot hides, how to tell it from termites, what repairs cost and how to fix it right.

By Patrick & Dylan · Florida Certified General Contractor, Lic. #CGC1541672 · October 8, 2026

St. Petersburg has a lot of older homes, and older homes have a lot of wood. Census data shows the median St. Pete home was built in 1970. About half of the city's housing units were built before then, and nearly 12,000 date to 1939 or earlier. Historic Kenwood alone, listed on the National Register in 2003, has one of the largest concentrations of bungalows in the Southeast.

Those homes have wood siding, wood windows, wood porches and wood trim, all sitting in one of the most humid climates in the country. In Tampa, average humidity at 7 a.m. is about 88% over the year. Rot starts small and quiet, and by the time paint is bubbling, the wood underneath is often soft. Catching it early keeps a small repair from turning into a big one.

Why Florida is so hard on wood

Rot is caused by fungi, and fungi need water and warmth. According to the USDA Forest Products Laboratory's Wood Handbook, serious decay happens when wood stays above its fiber saturation point, about 30% moisture. Dry wood usually sits at 20% or less. Decay slows down below about 50°F and above 95°F. In Tampa Bay, temperatures stay in that sweet spot almost all year. So any wood that stays wet, from a leak, a sprinkler or a spot where rain sits, is at risk.

Where to look

Door frames and thresholds, especially the bottom few inches of exterior door jambs
Window sills and trim, where water sits after rain
Fascia and soffit along the roof edge, especially under gutters that overflow
Siding and trim near the ground, or anywhere a sprinkler hits the house
Porch columns, railings and steps, where wood touches concrete or soil
Under sinks and around toilets, from slow leaks you can't see

Walk around your house once or twice a year, ideally after a heavy rain, and look at these spots.

How to spot rot

Press the wood with a screwdriver. Healthy wood pushes back. Rotted wood feels soft or spongy, or the tip sinks right in. Other signs:

Paint peeling or bubbling in one spot while the rest of the wall looks fine
Dark stains or a musty smell
Cracks running across the grain, or wood breaking into small cubes
Caulk joints that have pulled away and stay damp

Rot or termites?

They can look alike, and in Florida you often find both. Rot goes with moisture: the wood is soft, crumbly or stringy.

Termites leave different clues:

Subterranean termites build mud tubes up foundation walls and pack their tunnels with soil. Florida has native subterranean termites and the invasive Formosan termite. According to UF/IFAS, a Formosan colony can hold several million termites and forage up to about 330 feet. Their swarms run from early April to late June, peaking in May.
Drywood termites live inside the wood itself. Look for small piles of six-sided pellets that look like sawdust or coffee grounds, pushed out of tiny holes. Wood may sound hollow when tapped.

If you see signs of termites, have a licensed pest control company inspect and treat before repairs. Otherwise you can end up rebuilding over an active problem.

We've seen this firsthand. On a door replacement in a 1940s Crescent Lake home, we found old termite damage once the old door came out. We showed the homeowner and fixed it before closing everything back up.

What repairs typically cost

Cost guides give a starting point. Your price depends on how far the damage goes.

Repair	Typical range	Source
Window sill replacement	$155 to $405	Angi, Tampa prices, 2026
Exterior door frame repair	$355 to $860	Angi, Tampa prices, 2026
Fascia and soffit repair	$1,050 to $3,300 per job ($6 to $20 per linear foot)	HomeAdvisor, national, 2025 data

We couldn't find a reliable Florida-specific price for fascia and soffit work, so that row uses national figures.

The biggest cost factor is what's behind the trim. Rot that has reached the framing, a door's rough opening or the subfloor turns a trim job into structural work. That's the main reason not to wait.

How it should be fixed

Find the water source first. A leak, missing caulk, a clogged gutter or a sprinkler aimed at the wall. If you skip this, the rot comes back.
Cut out all the soft wood. Painting or caulking over rot only hides it. We cut back to solid wood.
Use materials that last here. Cellular PVC trim won't rot, and it costs more than wood: HomeAdvisor puts PVC at $3 to $7 per linear foot for materials versus $1 to $3 for wood. Use treated lumber where wood touches concrete, and seal every end cut. Very small soft spots can sometimes be repaired with epoxy filler.
Prime, caulk and paint so water runs off instead of soaking in.

If your home is in a historic district: St. Pete has 11 local historic districts, the newest being Mirror Lake in 2024. Check with the city's historic preservation office before changing exterior materials, like swapping wood trim for PVC.

Don't wait too long

Every rainy season gives rot more time to spread. A soft spot on a sill this year can be a rotted jamb and subfloor in two or three years. If you're not sure what you're looking at, we'll take a look as part of a free estimate.

We repair rotted trim, doors, siding, soffit, fascia and porches all over St. Petersburg and Pinellas County. See our exterior repairs page or ask for a free estimate.