A rotting wood garage door is usually repairable when the soft wood stops at the bottom rail and stile ends, and heads toward a rebuilt section or a new door once rot crosses the joints into a second section. Wood doors rot from the bottom up and from the joints in.
Splash soaks the lowest rail, water wicks into the end grain where the stiles stand closest to the slab, and it sits in any joint where the paint has cracked. Caught early, that is a carpentry repair. A few more winters and it reaches the parts that hold the door together.
The sections below help you decide what a rotting door needs. For hands-on repair of wood and custom doors, heavy carriage styles included, see our page on wood garage door repair.
Why wood garage doors rot in Portland
Decay fungi need wood that stays wet, and the lowest part of a garage door here is wet for much of the year.
The USDA’s Wood Handbook draws the line at 20 percent moisture content: wood kept drier than that does not begin to decay, and decay already underway stalls. The same handbook gives the moisture level that outdoor wood settles at in Portland in November as 16.8 percent, against 9.4 percent for Phoenix in January.
That leaves only a few points of margin before any direct wetting. Rain splash, a puddle against the bottom seal or a downspout emptying beside the jamb supplies the rest, and the wood at the door’s lowest edge crosses the line first.
Age adds to it. Census estimates date more than one in four of Portland’s housing units to 1939 or earlier, and a detached garage behind a house that old may still carry an early wood door, or a later one under decades of paint.
How a stile-and-rail door is built, and where it fails first
A traditional wood sectional is a frame of vertical stiles and horizontal rails holding thinner panels, and rot starts wherever end grain or an open joint meets water.
The bottom rail of the lowest section takes the most abuse. It sits closest to splash, the bottom seal or its retainer is fastened along it, and the bottom brackets that anchor the lift cables screw into it at each corner.
Next come the stile ends, where the vertical pieces meet that rail. End grain soaks up water far faster than the face of a board, so the lowest inch or two of a stile can go soft while the paint just above it still looks fine.
Panels are the third weak point. Solid wood panels float in grooves and can split, while plywood or hardboard panels can come apart in layers once water gets past the paint. A panel that has separated into layers gets replaced, not patched.
How to map the rot on your door
Probe the bottom rail, the stile ends, the hidden lowest edge and the joints above with an awl or small screwdriver and a flashlight, about fifteen minutes’ work that shows how far the rot goes.
- Start low on the outside. Press the point into the bottom rail every few inches along its length. Sound wood resists and the tip barely enters; rotten wood lets it slide in or comes away in soft fibers.
- Check the corners and stile ends. Probe where each stile meets the bottom rail, front and back, and the wood around the bottom brackets. Probe beside the bracket screws, but leave the screws themselves alone.
- Raise the door partway and look up at its lowest edge. That face is easy to miss when the door gets painted, and it often rots first, out of sight.
- Work up the joints. Probe where rails meet stiles on the lowest section, then the section above it. Rot that stops in the bottom rail is a very different job from rot climbing a stile into the next joint.
- Glance at the frame. Soft jambs, trim or header are a separate repair, and the alley garage guide deals with that side of the opening.
- Write it down. Note each soft spot, how far the point went in and how long the soft area runs. A photo of each spot with a tape measure in the frame is enough for a quote.
Repair, rebuild or replace: matching the fix to the damage
Small soft spots take epoxy, partial rail rot takes a spliced-in piece, full-rail rot takes a new rail or rebuilt section, and rot in two or more sections calls for a remade section or a new door.
| What the probe found | Usual fix | What to keep in mind |
|---|---|---|
| Small soft spots in otherwise firm wood | Epoxy consolidant, then epoxy filler, primer and paint | Lasts only if the water source is fixed too |
| Rot along part of the bottom rail, firm wood past it | Cut out the bad wood and splice in a matching piece | Seal every cut face, end grain first |
| Rot across the full bottom rail or into its joints | A new bottom rail, or a rebuilt bottom section | The bottom brackets come off, so the springs are unwound first |
| Rot in two or more sections, split or delaminated panels, a racked frame | A remade section or a new door | Weigh the cost of rebuilt sections against a new door |
Epoxy suits rot that is shallow and local: a liquid consolidant soaks in and hardens the softened fibers, and a paste filler rebuilds the shape. It fails when asked to bridge a void the size of a fist, or when the wood around it stays wet.
A splice, sometimes called a dutchman, replaces a length of rotten rail with new wood of the same species, glued and fastened in place. Done well, it holds paint like the original wood and handles larger damage than filler can.
When rot has crossed the joints of a second section, a rebuilt or replacement section is the usual route, and past that point our repair or replace guide helps weigh a new door.
Which parts of a rot repair belong to a technician
Anything that means removing the bottom brackets, the bottom rail or a whole section belongs to a technician, because the bottom brackets carry the full pull of the springs.
The lift cables climb from the bottom brackets to the cable drums at each end of the spring shaft, and the springs keep them loaded whenever the door is closed. Unscrewing a bottom bracket from a rotten rail with the springs wound can let the cable and bracket fly loose with real force.
Replacing a bottom rail or a full section means unwinding the springs, unhooking the cables, swapping the wood, then rewinding and balancing. New wood, epoxy and fresh paint also change what the door weighs, so we set the spring tension to the repaired door rather than the old one.
Lead paint on older wood doors
If the house or the door predates 1978, assume the paint may contain lead and keep the dust down whenever you scrape or sand.
That is the EPA’s own advice to do-it-yourselfers: homes built before 1978 may have lead-based paint, and when the age is unknown, treat it as if it does. The agency suggests misting surfaces before scraping or sanding, keeping any heat gun under 1,100 degrees Fahrenheit, and using power sanders only with a HEPA vacuum attachment.
Lay plastic sheeting under the door, keep kids and pets clear of the work area, and clean up with a HEPA vacuum and damp disposable cloths rather than a broom. Paint chips from an old garage door belong in a sealed bag, not the flower bed.
Keeping a repaired door from rotting again
A repaired door lasts only if its wood stays below that moisture threshold, which comes down to sealed end grain, sound paint and water moved away from the door.
- Seal new wood on every face before it goes in, end grain especially, and prime the cut edges of any splice.
- Refinish in July or August, Portland’s driest months, when the airport normals show barely half an inch of rain per month.
- Keep a bottom seal that meets the floor evenly, and replace it when it flattens or cracks; our seal and threshold service handles wood doors too.
- Point downspout outlets toward the yard rather than the apron, and fill any low spot that holds a puddle against the door.
- Keep moss, leaves and soil off the bottom rail and the jamb feet.
Mildew on a wood door is cleaned the same gentle way as on steel, covered in our rust, moss and mildew guide, and any dark stain under that growth deserves a poke with the awl.
If the probe test turns up rot in more than one section, or you would rather not choose between epoxy and a splice yourself, text a photo of each soft spot. We will put a repair price next to a replacement price, so the comparison is easy.