Wooden Window Sill: Repairing Of ?

[Robert11]

Hello:

Have a wooden window sill that has a few inches x a few inches missing from an outside corner. Not rotted out, this area is totally gone. Probably rotted first, then just broke off.

Hate to go to the expense of having a carpenter come in to replace the whole sill. Remember a few years back when we had one done, it was quite costly.

Was wondering if theres anything like "plastic wood" that would bond very well to the raw edge that was created, and that I can perhaps file or grind to the right shape after it sets up.

It would have to have a "mass" that would cover perhaps 4" x 4" x the thickness of the sill. Quite a "chunk," I guess.

Any thoughts on this would be most appreciated.

Thanks, B.

[hvacthruyouguys]

[Roger Taylor]

If the wood is porous, and it will be if it has any rot at all, apply several coats of fresh boiled linseed oil, several days apart, until the oil no longer soaks in immediately. This hardens the wood and makes a better base for what comes next. Then, after fully dry, sand off a fresh surface, paint the rough edge, preferably with a good acrylic fast drying primer. Then mix and apply Durham's Rock Hard Putty, an acrylic dry-mix repair compound available in the paint and filler section of any hardware store.. If the repair part is too big, you might need to build a little support piece of plywood topped with waxed paper so it will not stick, once the putty is dry. Prime and paint the repaired area, after some sanding. I use this putty for such repairs, and it works great, is easy to mix, and lasts forever.

[Kyle Boatright]

Believe it or not, Bondo (typically used in auto body repair) is excellent for this purpose. Follow the directions and apply several thin layers. One or two thick layers will crack due to the curing process...

KB

[ameijers]

Bondo is great for holes and soft spots, but lousy for sculpting shapes out of. If you make the 'ear' on a windowsill out of it, the first time somebody taps it with a rake, or leans on it, it will pop off.You need to cut/chisel away back to solid wood, and whittle a block to replace the missing stuff. Glue'n'screw with deepset screws that you can putty or plug over. Make it slightly oversize, so you can plane and sand it to a smooth transition. (Covering this joint is what Bondo or epoxy are good for,) Most of the DIY TV shows have shown this repair at least once- I expect that their websites probably have a step-by-step demo to follow. Other alternative is to saw off the front edge of windowsill, and add back a board. Ask This Old House had a segment demonstrating that. It helps if you have a similar window to copy off of- otherwise you have to copy the other side of same window, and 'flip' it all in your head. Don't forget the little groove on the bottom of the sill- very important for controlling rain runoff.

aem sends....

[Kyle Boatright]

You do have a point that unsupported bondo may chip. The way to overcome that is to drive a couple of screws into good wood, but leave the head and part of the shank sticking out. Then, you lay the bondo over the screws, which provide structural support.

KB