Replies

1. 
   Stray | Sep 26, 2006 10:48pm | #1

   Hi Housemom,

   I've done this on many different windows.  My process has been to use a sawzall with a bimetal blade and cut the sill out.  Plenty of hammer and chisle time as well. 

   Sometimes it's easiest to first make 2 cuts, essentially chopping the sill into 3rds.  Remove the middle section as carefully as possible so as to preserve it as a cross section with which to fabricate the new sill.  Then remove the end peices as gingerly as possible to avoid damaging the jambs and apron, sliding the blade between adjacent framing/casment members to cut the nails and free it up.

   If its a window of any history/significance, fab a new sill on the table saw with a blank of some rot-resistant wood (cedar, white oak, etc...) if it's a stain-grade application, match the species of wood on the remaining frame.

   If historical significance isn't of any concern, you could mill the new sill out of a composite material (ie Trex, or other brand) to give you a rot-proof sill.  Mike Smith does this, and I've used his tip before with good results.  It takes paint well.  The way you talk about the 100yr old windows, I doubt you'd want to do this though.

   It takes patience and attention to detail to fit in the new sill.  Make sure you fabricate the old sill as closely as possible to the old, including bevels, kerf under the exterior lip for shedding water, etc...

   If the rot is very localized and not too pervasive, you can chisle it back to good wood and just rebuild the sill with an epoxy product instead.

   Can you post a photo?

   Ithaca, NY  "10 square miles, surrounded by reality"

1. 
   housemom | Sep 27, 2006 12:37am | #2

   Here are a few pictures I have heard of the epoxy-is it hard to work with?

   thanks again

   
1. 
   NickNukeEm | Sep 27, 2006 01:26am | #3

   I've repaired worse using a two part epoxy, but you won't know the extent of the damage until excavating out all of the rot.  You could use a chisel, as suggested, but I found that a rotary rasp chucked in a die grinder works best; it's fast and precise (or at least fairly accurate.)

   Once the rot is completely removed, you need to decide if it's worth it to proceed with epoxy, or replacement.  Generally, if the excavated area does not penetrate the sill, and is not too large, I will use the epoxy.  Prior to mixing the epoxy, I fabricate 'dams' or 'forms' out of plywood that I screw to the sill once the epoxy is down as a make-shift form to keep the epoxy in place and form it to the shape of the sill, thus preventing a lot of sanding later.  Wax paper is used between the forms and epoxy to prevent the epoxy from sticking to the plywood.

   Prior to applying the epoxy (Minwax makes a good two-parter, though I buy Bondo by the gallon) I usually screw in a few screws into the excavated area to give a little 'tooth' to the epoxy.  Also, Minwax makes a hardener which should be applied to all areas to be epoxied.  It might take several hours for the hardener to cure enough to be coated.

   Mix and apply your epoxy (I usually apply it in about 1/2" coats,) lay wax paper over it, and screw down your forms.  Wear a mask and sand it smooth using a power sander.  Apply primer and paint as soon as practical.

   Of course, by the time you do all of that, it might be easier to just replace it, depending on if you need to fab a sill or can buy a reasonable facsimile.

    "I am the master of my fate, I am the captain of my soul."  Invictus, by Henley.

2. 
   BryanSayer | Sep 27, 2006 01:43am | #4

   Nick gives good instructions for using epoxy, but I suggest Abatron epoxy over Bondo. It is designed for exterior wood use, and I believe you can apply the epoxy right over the consolidant without waiting for it to set up. I haven't tried the Minwax products.

3. 
   reinvent | Sep 27, 2006 01:57am | #5

   They sell the wood restoration as a kit w/ the liquid epox and epoxy paste together.

   http://www.abatron.com

   
   

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   Edited 9/26/2006 7:00 pm ET by reinvent