Back To The Family Handyman
Del.icio.us
Digg
Reddit
Facebook
StumbleUpon
TwitThis
Painting siding
A Board That Won’t Hold Paint
Sometimes a piece of wood siding or trim peels while neighboring boards don’t, even though they all get the same sun and moisture exposure. In a case like this, the board itself is usually the problem.
Some boards won’t hold paint because of “mill glaze,” a glossy or waxy surface left when the board was planed at the mill. Cure this problem by sanding glazed areas. Grain pattern can cause a more common and difficult problem. Dark bands of grain (called “latewood”) are less porous and stable than the lighter bands of wood, so paint doesn’t stick to them very well. This isn’t a problem when those dark bands are narrow and uniform. But when they’re wide, paint soon loses its grip. In fact, you can sometimes see a board’s grain pattern right through the paint as cracks and peeling develop along the latewood grain lines.
A board with tight, straight grain holds paint well. Wide bands of darker “latewood” lead to peeling. Regardless of grain, look out for “mill glaze,” a wood surface that looks glossy and paint won’t stick to.
If you have a few bad boards on your house, you can delay peeling by sanding thoroughly with 60-grit paper before priming. That roughens the dark bands so they hold paint better. But the only long-term cure for a bad board is replacement. Before you get started, measure the width and thickness of your siding. Keep in mind that about an inch of the board’s face is covered by the board above. Buy matching siding at a lumberyard; most home centers don’t carry it. Expect to pay 50¢ to $1 per foot.
To remove a bad piece of siding, you have to pull out two rows of nails: the ones in the bad board itself, and those in the board directly above. Siding is thin and splits easily, so the tricky part of this job is pulling nails without damaging surrounding boards. A cat’s paw ($5 at home centers and hardware stores) is the best tool for digging out nails if damage to the surrounding wood doesn’t matter .
To get at the nails in the board above, shove a flat pry bar up under it and gently pry the board outward. In most cases, this will pop up the nailhead, so you can pull it with your hammer claw. If you run into a stubborn nail that won’t move easily, don’t use brute force and risk splitting the good board. Instead, slip a hacksaw blade behind the siding and cut the nail.You can’t get the new board in unless you pull the remaining shank of the cut nail.
Before you install the new board, lightly sand it with 80-grit paper. If you come across shiny, glazed areas, sand them thoroughly. Then prime the backside and the ends. Also prime the ends of adjoining boards. This step pays off by slowing the moisture penetration that can lead to peeling at the joints. If the new siding is redwood or cedar, buy a special “stain-blocking” primer. Both of these woods contain natural chemicals (tannins) that can bleed through paint, causing brownish stains. A stain-blocking primer will seal in the tannins.
Nail the new board into place with 8d galvanized nails. Use a nail set to countersink the nailheads slightly below the wood’s surface. Countersinking nails helps to keep the heads from protruding as the wood shrinks and swells. After you prime the sunken nailheads, keep an eye on them for a few minutes; primer may drip out of the craters and leave runs on your siding. When the primer is dry, fill the craters with caulk. Also caulk the ends of the board, where it meets trim or the next piece of siding. Finish the job with two coats of acrylic paint.
Advertisement 
