I have a couple of 2"x12"-15' facia boards. They get a lot of sun in summer
and rain in winter. The wood has split in cracks as wide as 1/4". Since the
boards were developing dry rot in the cracks I treated them with
borax/antifreeze. Then I caulked them with flexible spackle compound.
Trouble is, due to the constant expansion and contraction of the wood, the
caulking is forced out of the cracks. I thought of applying some Bondo (or
similar epoxy) to the cracks or to the entire boards.
Will this work or will the Bondo pop out, too? Can I use some semi-liquid
bondo and paint it on?
The boards are difficult (expensive) to replace because they are tied in
with the roof tiles.
I've used automotive type Bondo with good effect on lots of outdoor wood
cracks. It isn't all that great at water resistance, so you have to make
sure it's well painted.
Depending on the applicatin, sometimes I'm able to insert a few screws
or nails "inside" the cavity I'm filling so that the Bondo can grab onto
them and keep from popping out if it's adhesion to the wood isn't too good.
I've always used just the automotive Bondo, 'cause it's easy to buy at
local auto parts stores, but Bondo makes an s-load of home repair
products, some of which might be better for your application. See:
Give it a try.
I can't find the post now, but I recently read that because Bondo
hardens to a solid, you may have popping out due to the wood expanding
and contracting around it. Some sort of flexible epoxy product was
recommended. If I find it I'll post back. Maybe someone else has the
name of it....
Siding professionals I've heard from always recommend against using
Bondo. You need something flexible that will move with the expansion
and contraction of the wood.
Prime first so the caulking (or flexible filler) has something to stick
to, then apply the caulking/flexible filler.
Here's a link for the Boracare wood preservative story and recipe:
I personally find that mixing with boiling water is sufficient to hold
solution if you will apply right away. Boiling with a candy thermometer
results in a superior batch with long shelf life.
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