Monday, September 25, 2006

Layman's Guide to Fixing Wood Rot

To a house made of wood, wood rot is like like rust on a boat- cancer. It can lurk silently, unnoticed for years, slowly eating away sills, joists, windows, siding...
We found our wood rot when we began painting the house. The scraping process is unforgiving to wood rot- the slightest touch of a scraper to rotten wood sends it crumbling. Luckily, we didn't find much rot in the siding. The window sills and trim boards were another story.

Fixing wood rot isn't hard, but it does take an understanding of important chemical products. And when you go to paint an old house, it is likely that you will find some. (DON'T just paint over it!)
Sean, the carpenter in the house, knew what to do when he saw the rot. Here's my "layman's guide":
Tools you will need:
* Wood Hardener or "Penetrant"
* Epoxy Filler
(see description and recommendation of brands below)
* Rubber gloves
* Disposible containers for mixing products
* Putty knife
* Sandpaper/ Sander
* Paint to finish
Products that restore rotted, severely damaged wood components are especially valuable for parts that cannot be replaced because of size, shape or other reasons. They are also helpful for parts that are particularly difficult to replace- like window sills.
Here's the chemical lingo:

The penetrant:
Reinforces, rebuilds, water- and insect-proofs wood by hardening after penetrating. Halts rot in windowsills, frames, structural and decorative parts, furniture, boats, columns, floors.

Epoxy fillers:
Like a structural adhesive putty and wood replacement compound. They are a high-strength no-shrink adhesive paste to fill, repair and replace wood and other materials in structures, walls, floors, furniture, sculptures. They are unaffected by water and insects.

Wood Rot Products:
Abatron's LiquidWood and WoodEpox
Advanced Repair Technology Inc.
Rot Doctor's Penetrating Epoxy and FILL-IT™ Epoxy Filler

The steps:

1) First, why is there rot in the first place? Check for the obvious - roof and plumbing leaks, and missing or punctured flashing. Look for stains and drip tracks caused by ice dams. Are eaves wide enough to prevent water from cascading down sidewall's? Are gutters poorly maintained or missing? Do finish grades slope towards or away from the foundation? Are foundation cracks admitting water? Is untreated wood in direct contact with concrete, masonry, or soil? Finding and treating the source of the rot is as important as fixing the structure.

2) Find out how bad the rot is. Take a scraper or knife and gently tap the rot until you get to solid wood. It's important to know how much rot you have and make sure you have an area appropriate for fixing. What's appropriate? When you take a look at the prices of the epoxies and penetrants, you'll get a sense of that! ;) (Our pics also give you an idea). If it's a really big section of rot, you will probably need to replace, rather than repair. If it is rot on a serious structural piece if the house (Joists, for instance), also consider replacement. If replacement is necessary and only part of a board is rotted, you can also cut and replace only that portion of the board to save materials and money.

3) Once you have the rot cleared away, you will need to apply the wood hardener, or penetrant, to all the remaining wood to stop the rot. Read the instructions of the product carefully. This needs to absorb and set, usually for about a day.

4) After you have hardened the wood, you are ready to apply the epoxy. Again, read the instructions for the epoxy you choose. This is where the mixing comes in, as most of them come in two parts and need to be mixed to harden. Use gloves! Apply the epoxy and work it into the shape of the wooden structure you are fixing. It's a little like working with playdough...

5) Let the epoxy dry- also about a day- before sanding. Sand it into the final shape, and it is ready for painting.

Voila! New wood. (Sort of.)


Wood Rot Resources (Highly Recommended!):
Restoring wood with epoxy
Wood rot repair


1 comment:

Susan said...

Sean,
You missed the easiest product!! Using Git Rot means you don't have to remove roted wood fibers. They actually help the two part epoxy to saturate the wood with capillary action!!!!! It can be sanded and painted after treatment too. Very easy to work with. I found it on the Internet, I think Boat Life makes it.

Susan