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handyman on call

Do-it-yourself window sill replacements

Q. My house was built in 1953. It was a ranch, until we enlarged it in 1996 to a Colonial. I just noticed that the sill in my original picture window has started to rot and the sills in the upstairs are spongy and rotting. I saw an episode on “This Old House” years ago where they cut the sills in half and replaced them, but I can’t remember how they replaced them. Help!


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A. I too have written and talked about replacing sills, probably before the “This Old Housers” did. Not to hit them too hard, but they probably used $1,000 or more worth of tools.

 Here is how it is done, with a minimum of tools, and mainly instinctive talent. Raise the window and remove the storm, then remove the inside sill, exposing the sill along its full length. Cut it in half laterally, so you have two halves about the same size. Then pry out with a pinch bar, or other prying device, each piece. You will have to worry them out, one by one, because they are usually nailed to the upright jambs. Work slowly and evenly. Each piece will yield, if you are careful. Save the pieces to use as a template for the new sill.

 You will find lots of nails left dangling, so cut them off. You may be able to find a replacement sill at an independent lumber store; I think Brosco sells them. If you can’t find a standard sill, you can make one out of a pressure-treated 2x10 or 2x12. It has to be as wide as the original sill. Cut the new sill to match the old, then put it in place.

 But it must slope as much as the old one did. This slant will help prevent future decay. To make it slant, put in a long piece of slat or lath under the inner side. This sill should butt up under the sloping ends of the jamb. Before you do that, saw a kerf (groove) on the underside of the sill, about an inch from the outer edge of the sill along its full width. This will prevent water dripping over the edge from percolating further up and causing decay. I have replaced several sills, so I know this technique works well, especially with pressure-treated wood, which can be primed and painted or given two coats of a stain.

 There is a reason your sills rotted. Check the tops of each window to see if there is a window flashing over the top casing. Such a flashing is an aluminum cover folded into an L shape; one ell is slipped under wall shingles, the other part covers the casing and folds over its edge — usually folded at the ends. As simple as this is, it keeps water out. The upstairs part, built in 1966, might have used caulking only, which will not work. If there is no flashing, put it in.

Q. Some years ago you helped us solve a problem caused by woodpeckers attacking our shingles. While your advice to hang aluminum pie plates made the house look [festive], it worked. Now on to a different problem: Yesterday we awoke to a stench from the basement which drifted up to the kitchen. We’re convinced something died but we can’t find the evidence. Who should we call?


A. There are three specialists on animals, stenches, and corpses, any one can be helpful. Call an exterminator, odor locater, or disposer of dead animals. They are in the Yellow Pages under various designations. Dead critters, even mice, can stink for weeks.

Peter Hotton is also in the g section on Thursdays. He is available 1-6 p.m. Tuesdays to answer questions . Call 617-929-2930. Hotton ( also chats online 2-3 p.m. Thursdays on
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