Repairing Water Damage and Wood Rot in Doors

Doors have a high rate of wood rot due to backsplash from landing immediately below Door thresholds, kick plates and surrounding trim are susceptible to wood rot. When water splashes up from the landing just below the door and gets into the cracks, and the wood doesn’t dry out, wood rot happens.

All exterior doors must have a landing in compliance with building code safety requirements. Typically there are only 8 inches between the landing and the door threshold, setting the stage for water to splash up and hit the house. Water run-off from the roof makes the problem worse by adding to the amount of water hitting the landing. That means even more water will splash back up against the door and house.

Frequent Wood Rot Victim – Front Doors

Because front doors are not used much, water problems can go undetected for some time. The wood rot around the front door pictured here was found when the homeowner started to touch up the paint on the door trim. After a few pokes at the trim, the severity of the problem was obvious. Time to call in a handyman.

In this case, the homeowner was taking care of her home by painting the door and window trim. Unfortunately, improper installation of the flashing during construction was the source of the problem. Since the house was only 5 years old, this first-time homeowner had not been focused on home maintenance compounding the damage.

The extensive wood rot on this front door required the following repairs:

  • Siding removed and sheathing (plywood layer behind the siding) replaced.
  • New front door, threshold and kick plate installed. Wood rot under door’s bottom weatherstripping made the door unusable.
  • Used Azek, a composite with no wood content, for door trim to avoid future problems.

You may not realize that exterior paint is the first line of defense against water damage. When wood is not properly sealed by caulking and painting, it absorbs water creating an environment where nasty organisms eat the wood. The damage starts as fungi break down the wood fibers and decomposition sets in.

The human eye may not be capable of seeing this damage for some time. Water can find a path up the kick plate under the door, and reach the threshold. It may also penetrate the vertical wood trim and door jambs which sit on top of and touch the threshold.

Another Common Wood Rot Victim – Sliding Patio Doors

Sliding patio doors that open onto a deck or patio very often have wood rot problemsSliding patio doors typically open onto decks creating a splash back situation somewhat similar to front doors (described above). However, the wood rot problem with patio doors is frequently due to improper installation of the ledger board which attaches the deck to the house.

Flashing must be properly installed to prevent water from getting behind the ledger board used to attach the deck to the house.  If water collects, you’ve created an environment for fungi. And the trapped moisture can seep behind the siding and sheathing on the house where the deck will hide the damage, sometimes for years.

This newly retired homeowner lived in his home for 20 years and was unaware of any major problems. When reviewing DIY repairs to make before listing his house for sale, he was shocked to find the damage shown in the photo. Instead of making repairs himself, he needed a handyman. The extensive repairs included replacing structural wood, insulation, plywood sheathing and siding about 8 ft back from the patio door. The door had to be re-framed, and the threshold and rotted deck boards had to be replaced.

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