Replace a Deteriorating Windowsill
LESLIE: Bob in Ohio is looking to do some work on his windows. How can we help?
BOB: Hi. I have a rental home. It’s about built in the mid-70s. And the builder must have used some kind of a composite board in the windowsills and they’re starting to deteriorate. What … what’s involved in ripping out a windowsill and putting it in without disturbing the plaster too much?
TOM: Do you have a window trim around this? Or is it basically plaster on all … on the sides and the top and just one window sill at the bottom?
BOB: That’s correct. Plaster all around and a windowsill on the bottom.
TOM: OK. So the secret here is to do this very carefully. You probably have a piece of what’s called apron under the windowsill. And you need to remove the apron. And then, the easiest way to do this is with a reciprocating saw or saws awl because it helps to get under the windowsill and be able to cut the nails that are there to loosen it up. Because this way, you have less prying and wiggling and jiggling and less chance that you’re going to mess up that spackled edge.
So I would say, pull out … pull off the apron first, then try to free up as many nails as you can. You might want to take a utility knife and cut the edge where the jamb – the side jamb of the plaster wall – meets the window sill, so that you have sort of a clean edge for it break there and see if you can work that out.
But now, you mentioned, Bob, that these are composite window sills. If they’re composite, then I presume …
LESLIE: They wouldn’t be breaking down.
TOM: Yeah, they wouldn’t be rotting. So is it just a discoloring issue?
BOB: Oh, no, they’re coming apart. They’re … like they’re flaking apart.
TOM: Oh, OK.
BOB: Forty years of moisture, I guess, in the windows, running down onto the windowsill, laying there.
TOM: Alright, because Leslie and I are probably thinking the same thing. Why aren’t you painting them? And you’re saying they’re physically deteriorating so you have to remove them. Well, that’s the best way to do that.
Now, after you get the window sill out, if there’s repairs to be done – because inevitably, you’ll probably have a little bit of spackle repair there – make that first and then assemble the new windowsill last.
BOB: OK, and what … now, I won’t be able to get in there and nail. Would I … do I use liquid nails or something to hold it in?
TOM: No. Certainly you could get in there and nail. Basically, you slide the new windowsill in, you draw up some nails on a slight angle – sort of towards the glass, so that you catch it in a couple of different places, and then you put the apron – the new apron – back up underneath it and tack that into the jamb under the window. And you’ll be able to support it just fine.
BOB: Well, there’s got to be some plastic work, too, because the plaster is deteriorating (inaudible).
TOM: Well, you know, Bob, the three most expensive words in home improvement – “might as well.” (laughing)
BOB: Might as well, exactly. And your program is well-named, too – “Money Pit.” (laughing)
TOM: Alright, Bob. Well, hopefully, we’ve made yours a little bit less of a money pit today.