Have some wooden window sills with some decent size (rotted out) holes
in them on the outside portions.
a. One Contractor wants to cut them off, flush, on outside and just
screw in a new sill piece. Says that replacing the complete whole sill
as a single piece is a "big job".
Is this just screwing in a wooden replacement piece for the outside a
good approach ? Or,...?
b. If I try to plug up and fill the holes myself, sand smooth, and then
re-paint them, what product should I use ?
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Wood rot is like an infection. You can fill in the holes, but the rot
will continue to eat the remaining wood. There may be treatments
available that will kill or neutralize the rot. I've read that diluted
ethylene glycol, used in some auto antifreeze, is effective.
The contractor is probably right about replacing the entire sill being a
big job. His suggestion is somewhat equivalent to your idea of filling
in the holes, but may be the easiest approach unless the rot extends
deeper than you think.
When I had a similar problem with a seldom used door, one carpenter
recommended digging out the rot and using Minwax "High Performance Wood
Filler". It appears to be a kind of epoxy, and must be mixed with a
liquid hardener before use. (Another suggestion was to use Bondo.)
In my case I waited too long, and the bottom of the door fell off! I
opted to replace the entire door as part of a major renovation.
I've done all the methods you list, depending on
the situation. Replacing the sill is a big job, as it's
under the window, and usually part of the window.
So that means removing interior and exterior trim
as part of the job.
If the rotted spots are contained you can clean
them out and fill with Bondo automotive filler. Then
prime with linseed oil primer and repaint. (Water
base paints will not hold up on sills. If you use water
base trim paint you can still at least use a good oil
If the rot is on the outside it's often feasible to
cut off the outer 1-2 inches and replace it. You
just need to match the pitch and size of the existing
wood. Also, use fir. Pine will rot quickly in that usage.
And be sure the joint is good. You don't want water
getting in there.
If the sill is very bad, and your finances are limited,
and you don't care much about appearance with that
particular window, another option is to do what you can
with the sill and perhaps soak it with linseed oil to
protect it in the future, then put a piece of sheet
aluminum over it so that no more water gets in. Ugly,
but it works.
The final option would be to replace the sill(s). In that
case you'd want to do it when you're repainting either
inside or outside, if possible.
| Have some wooden window sills with some decent size (rotted out) holes
| in them on the outside portions.
| a. One Contractor wants to cut them off, flush, on outside and just
| screw in a new sill piece. Says that replacing the complete whole sill
| as a single piece is a "big job".
| Is this just screwing in a wooden replacement piece for the outside a
| good approach ? Or,...?
| b. If I try to plug up and fill the holes myself, sand smooth, and then
| re-paint them, what product should I use ?
| This email is free from viruses and malware because avast! Antivirus
protection is active.
first remove ALL the loose and soft stuff, then use dry rot liquid
compound. It seeps into the soft wood and cures pretty hard on its own.
Then use the epoxy compound to fill out flush, be sure to sand as soon as
possible gets HARDER with time.
I actually reconstituted missing corners freom some antique windows. where
there was nothing left but the paint surface.
I prolonged the life of my windows pulling rotten sills and replacing
with pressure treated lumber. Got over 30 years with most of my windows.
Eventually had to replace all my windows and did not use wood.
Don't tell people stuff like that because it only creates worry and
confusion, especially if they're new to home ownership and don't know
who or what to believe.
As long as water isn't getting into the wood, the wood rot should
stop and the wood rot fungus (latin name: Serpula Lacrymans) will go
dormant for a few years and then die. So, even if you covered that
whole window with a shower curtain from the outside to keep it dry, the
wood rot would stop.
You can kill the wood rot fungus by simply removing any rotted wood
and painting wood end cut preservative onto what's left. Wood end cut
preservative contains the active ingredient copper naphthalene. It is
the copper in copper naphthalene that is a natural biocide. There are
other natural biocides including zinc, boron and arsenic. Zinc oxide,
for example is used as the white pigment in many EXTERIOR paints because
the zinc naturally keeps any shaded areas on the side of a house free of
mold growth. The zinc kills the mold spores before they have a chance
to grow and affect the appearance of the paint. Boron based wood
preservatives are popular in log homes and for protecting telephone
poles because the borates are highly soluble in water and gradually
penetrate throughout the entire cross section of the wood logs or
If you paint copper naphthalene onto the surface of wood that is in
the process of rotting, the copper will kill all of the wood rot fungus
it comes into contact with. The copper will also prevent the wood rot
fungus from growing in any wood that has copper naphthalene in it.
You can buy end cut preservatives for wood which will typically
contain about 12 percent copper naphthelene. That percentage goes up to
about 24% if you buy an end cut preservative for the wood used for
pressure treated wood foundations for houses. Since that wood will be
underground all the time, it needs more protection. You can also go to
any feed lot, horse stables or veteranarian and buy a copper naphthalene
based treatment for a condition known as "Thrush" in horse hooves.
Thrush is caused by a fungal infection, and the copper in copper
naphthalene kills that kind of fungus too. Thrush treatment for horse
hooves will typically be 37.5 percent copper naphthalene, which is much
higher than you can get in any wood end cut preservative.
Also, if you have some end cut preservative available to you, you
can build up the copper naphthalene content in the wood by applying
multiple coats. The trick is to allow sufficient time for the solvent
thinners in the end cut preservative to evaporate from the wood before
applying another coat. Each time the wood dries out and you paint more
end cut preservative on, you increase the amount of copper naphthalene
remaining in the wood, thereby providing greater and greater protection
against wood rot taking hold in that wood again.
You should also know that wood absorbs liquids and allows them to
evaporate from the wood 15 times as fast at the end grain of the wood
than across the wood grain. So, whenever treating any wood with end cut
preservative or wood deck sealer, it's most important to apply plenty of
product to the end grain at the ends of the boards.
If it were me, I would be inclined to replace the whole window with a
new PVC window. That way, you don't have to worry about wood rot at
all. That will give you a maintenance free window so that you only have
to check that the caulk is in good condiiton. Also, it adds to the
value of your house because any potential buyers is going to benefit
from that window having been replaced with PVC.
Regardless of what you do, caulk your repaired or replaced window with a
caulk known as Kop-R-Lastic. Any place listed under Caulk and Caulking
Supplies listed in your yellow pages phone directory will be able to
order Kop-R-Lastic for you. Kop-R-Lastic is a synthetic rubber caulk
whose cohesive strength is even higher than it's adhesive strength,
which means it sticks to itself even better than it sticks to common
building materials. That means, if you ever need to replace the caulk
around your window, you simply get one end of the Kop-R-Lastic loose and
it pulls of the window like a rubber rope. I own a small apartment
block with 66 windows, and I won't use anything but Kop-R-Lastic on
them. Also, it's best to opt for the clear Kop-R-Lastic instead of any
coloured Kop-R-Lastic because the colour comes from tiny coloured
particles (called "pigments") that are added to the clear Kop-R-Lastic
caulk, and those pigments lessen both the cohesive and adhesive strength
of the cured caulk. Kop-R-Lastic is now manufactured in the USA under
licence from the Koppers Company of Australia by the Henry Company of
I had three rotted window sills replace prior to having the house painted.
Same fellow did the replacement. He did it from the outside--didn't touch
or damage anything on the inside; that is, didn't remove the inside trim and
didn't remove the window sill. Used a sawsall (????), went along underneath
the sill cutting all the nails. Slipped in the replacement and nailed in
place without disturbing the sill. I didn't think it could be done but he
did it without a problem. Not wanting to disturb the inside finish I
initially suggested going the route of cutting flush and screwing on a
replacement piece. He scoffed at the idea and said let's do it the right
way. Came out great!
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