Seasonal Wood Rot Inspection Guide for St. Louis Homeowners
A season-by-season maintenance calendar to help you catch wood rot early and protect your home year-round. St. Louis's climate is uniquely harsh on exterior wood — here's when to check and what to look for.
Published: March 2026
St. Louis homes face a year-round assault on exterior wood. Winter freeze-thaw cycles crack seals and let water in. Summer humidity accelerates fungal growth. Spring storms dump heavy rain against already-compromised surfaces. And fall leaves trap moisture against wood.
The difference between a $300 repair and a $3,000 replacement is often just timing. Regular seasonal inspections catch problems when they're small, saving you significant money and preventing structural damage. Here's exactly what to check and when.
When your inspection reveals damage you can't handle yourself, find a wood rot specialist in St. Louis through the Wood Rot Experts network—matched to your specific repair, whether it's a deck, window sill, or fascia board.
Spring (March - May)
The Critical Inspection Window
Spring is the most important inspection time in St. Louis. Winter damage is now visible, and you have a window to make repairs before summer humidity accelerates any existing rot.
Deck
- Check all deck boards for soft spots, especially around fasteners
- Inspect joists and beams from below — probe with screwdriver
- Look for posts sitting in standing water or soil contact
- Check railing connections for wobble or soft wood
- Examine ledger board connection to house
Windows
- Test all window sills with screwdriver — especially south and west facing
- Check drip caps above windows for cracking or separation
- Look for paint failure around frame corners
- Open and close all windows — sticking suggests swelling from moisture
Doors
- Probe threshold and jamb bases — the most common rot location
- Check kick plate area for soft spots
- Look for gaps between door frame and masonry
- Test weather stripping seals
Siding
- Inspect bottom courses within 6 inches of ground level
- Check behind downspout terminations for splash damage
- Look for lifted, cupped, or buckled boards
- Examine corner boards and trim joints
Roof Line
- Inspect fascia boards from the ground with binoculars
- Look for paint peeling on soffits — indicates trapped moisture
- Check rake boards on gable ends
- Look for staining or discoloration below gutters
Summer (June - August)
Monitor and Protect
St. Louis summers bring 70-80% humidity that accelerates rot in compromised wood. This season is about monitoring known weak points and maintaining protective coatings.
Deck
- Check for trapped moisture between deck boards (feel for dampness morning vs afternoon)
- Ensure proper ventilation beneath the deck
- Watch for mushrooms or fungal growth on wood — a sign of active rot
- Re-apply sealer to any bare or worn spots before fall
Drainage
- Verify gutters are clear and draining away from the house
- Check that downspout extensions direct water at least 4 feet from foundation
- Look for pooling water around deck posts or foundation wood
- Ensure sprinklers don't hit wood siding or trim directly
Ventilation
- Confirm soffit vents are not blocked by insulation or debris
- Check attic temperature — excessive heat indicates poor ventilation which traps moisture
- Ensure crawl space (if applicable) has adequate air flow
Fall (September - November)
Seal and Prepare
Fall is your last chance to seal and protect wood before freeze-thaw season. Any repairs should be completed before the first hard freeze, typically late November in St. Louis.
Caulk and Seals
- Re-caulk all wood-to-masonry junctions (window frames, door frames)
- Seal any cracks in paint or finish coats
- Check and replace weather stripping on doors
- Seal end grain on exposed lumber (decks, trim cuts)
Gutters
- Clean gutters and downspouts — blocked gutters overflow onto fascia
- Repair any leaking gutter seams
- Ensure gutter slope is correct (no standing water)
- Install gutter guards if leaves are a recurring issue
Ground Contact
- Clear mulch, leaves, and debris from around foundation wood
- Cut back vegetation touching siding or trim
- Ensure 6+ inch gap between soil and any wood
- Verify that grade slopes away from house
Winter (December - February)
Watch and Document
Active repairs aren't practical in St. Louis winters, but you can identify problems to address in spring. Freeze-thaw cycles will reveal weak points in paint and seals.
Visual Monitoring
- Look for ice forming in cracks or joints on exterior wood — water is getting in
- Watch for icicles forming from soffits or fascia — indicates ice dam or moisture issue
- Note any new paint bubbling or peeling after freeze-thaw cycles
- Document damage locations with photos for spring repair planning
Interior Signs
- Check for condensation on interior window surfaces — indicates seal failure
- Look for water stains on walls/ceilings near exterior wood junctions
- Feel for drafts around door and window frames
When to Call a Specialist
Not every finding requires professional repair. Here's how to gauge severity.
Monitor (Low)
- Minor paint peeling in small areas
- Hairline cracks in caulk joints
- Surface discoloration without softness
- Slight mildew on wood surfaces
Action: Address during regular maintenance
Schedule Repair (Medium)
- Soft spots found with screwdriver test
- Visible rot in non-structural wood
- Paint bubbling or extensive peeling
- Wood feels spongy but still has shape
Action: Get a specialist assessment within 1-2 months
Act Now (High)
- Structural wood is soft or crumbling
- Deck feels bouncy or unstable underfoot
- Wood is breaking apart or missing chunks
- Active water intrusion around rotted areas
Action: Get a specialist assessment ASAP
Found something during your inspection?
Describe what you found and we'll match you with a vetted local specialist for a free assessment. Catching it early saves money.
Get Matched With a SpecialistFrequently Asked Questions
When is the best time to inspect for wood rot in St. Louis?
Early spring (March-April) is the best time for a thorough inspection. Winter freeze-thaw cycles will have revealed new damage, and you can address repairs before summer humidity accelerates any existing rot. A secondary check in late fall before the first freeze is also recommended.
How often should I inspect my home for wood rot?
In St. Louis's climate, inspect exterior wood at least twice per year — once in early spring and once in late fall. High-risk areas like decks, north-facing siding, and ground-level wood should be checked quarterly. After any major storm or extended wet period, do a targeted check.
What are the first signs of wood rot?
The earliest signs include paint that's peeling, bubbling, or cracking in isolated spots; wood that feels soft when pressed with a fingernail; discoloration or darkening of the wood; and a musty smell near wood surfaces. The screwdriver test is the most reliable — if a flathead sinks easily into the wood, you have rot.
Stop Wood Rot Before It Spreads
Wood rot doesn't improve on its own — it only gets worse and more expensive. Get matched with a vetted local specialist and discover how much you can save with expert repair.
Serving all of Greater St. Louis including Clayton, Webster Groves, Kirkwood, Ballwin, Chesterfield, and surrounding areas