Window sill repair / replace

[Pat Barry]

I need some advice on the best way to proceed with repairs in order to fix a rot issue that is present on the outside window sill for a large picture window with two side casement windows. As you can see in the photo's, there is significant rot. I would like to repair this and would like some direction on the best approach. Note - I have seen some you tube videos with epoxy fill and others where they completely cut away / chisel out the old sill and then fit in a replacement. I am leaning toward that method since the damage looks extensive. I am hoping that I don't have to pull this window out in order to make a good fix since it is large and heavy and I am usually just working there (at my cabin) by myself. The vertical moldings look OK. I plan to pull the two casement windows out, strip them down, repair them, prime and paint them and reinstall. Alsoo, for what its worth, this window faces pretty much due south with full sun exposure
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[Lloyd McKinlay]

Take a look at the Abatron line of wood restoration products. My experience is the repairs are permanent.

[Greg R Bradley]

One thing to remember as you fix it:

Some old houses built to last forever slope the sill at 30 degrees to flow the water away from the window and so the water doesn't ever sit.

Production houses, which is about all that is built post WWII, slope their sills at 5 degrees. That worked OK for the period they needed to last as long as they were built out of all heartwood lumber.

Second Growth Lumber forced them to go to 10 degrees and now 15 degrees.

Slope it whatever works OK and extend the lip past the siding as much as you can. Build a lip at the bottom outside edge so that you make a "drip edge".

If you decide to replace the wood, use Boral to eliminate water effects completely.

www.boralamerica.com (http://www.boralamerica.com)

[Rod Sheridan]

I did that at my Mo's house.

It was a bow window, I make new sills out of cedar on the shaper. replaced them one section at a time, caulked and painted.

I think it was a 20 degree slope.

Worker great............Rod.

[Peter Quinn]

IME you can take back almost anything with abetron wood epox and some penetrating epoxy to consolidate the funk that is left. It's hard to assess the damage from the photos, but a lot of time the sill is the one part if rather replace than repair. It's the second easiest way in for water, probably the hardest working part of the window, and it's tough to dry it out enough to effect a proper repair in place, so you may wind up pulling the window....and at that point why not just replace the sill anyway. Some sills can be fixed in place if you have access from inside, may involve pulling off some wall board to cut the old nails and attach the new sill, some times it's really more practical to pull the whole unit, and nobody ever wants to hear that, but if the sill is only half attached to the jamb legs, you leave a nice place for water to get in, the whole thing keeps moving around, caulk breaks, 8 years later you are making another sill....you have to assess the site conditions to determine what approach is best for your situation. I've seen them made of cedar, Spanish cedar, white oak, mahogany, and urethane. If it's getting painted the plastic can be a very final solution, might involve laminating two pieces to make thickness.