Subject: house sill beam repair
Date: Thu, 11 Jul 2002
Questions about amounts and types of product:
Problem is 6' section of sill beam in 100 yr old house -
bought house with localized carpenter ant problem and earth up onto
siding in same spot (surprise). This is same spot where some
mysterious work had been done involving removal of a few inches
of sill beam outer surface. Last year killed ants and
changed grading so that foundation is exposed - therefore
the wood is now pest-free and dry. Have access to outside
and most of top of beam, but access to inside of beam would
2 ft section is seriously rotted - only top few inches
of a 6 x 6" is intact and the rest is dry one-inch chunks
of wood falling out. Problem tapers away until only the
bottom 1 inch is rotten and flaky. Ant tunnels do not
appear extensive in this area. Structurally, we have one
stud of a two-story house sitting on almost nothing -but
there's no indication of movement, so far.
Plan is to buy CPES, L&L resin, and some epoxy filler. Will
get syringe kit and sawdust.
Since you have good access to the top and will therefore be able to
drill 3/8" (or larger) access holes, I don't think you will need the
syringe kit. CPES can be applied easily to these areas with a turkey
baster, and so can the Layup & Laminating Resin by popping off the bulb
and pouring in the mixed resin.
Will use pressure treated wood
as dutchman fill in the large area.
Well, okay, if you want...but it is our personal opinion that untreated
wood doused with CPES (after cutting and trimming) produces a more
permanent rot-protected dutchman. The quality of pressure treated wood
varies considerably...some is okay and some is not. The petro-based
chemistry used in some of the pressure-treated wood will interfere
somewhat with the penetration of CPES.
How much quantity of products?
For the CPES, I would estimate two of the 2-quart units of CPES, unless
you plan to spray other undamaged areas of the beam for future
protection, in which case we would suggest the 2-gallon unit.
The amount of the Layup & Laminating Resin you will need is more
problematic, since you can't really know how much there is to fill
inside the beam, or how much you may lose through leakage. I would
suggest at least two of the 2-quart L&L units, and, again, to be sure
you may want to order the 2-gallon unit of the resin. I can't imagine
that you would use more than 2 gallons. You will also be using the L&L
Resin mixed with sawdust into a putty mix for closing access holes and
for the possible fill of any remaining gaps/cracks/holes. This will
serve the same purpose as our Fill-It Epoxy Filler and save you having
to buy three items.
Use lacquer-thinner for cleanup and equipment flushing.
How many drill holes per square foot (as seen from the top?)
- do I use these for both CPES and L& L?
We would suggest staggered holes drilled every 4-5 inches. More are okay
if you think they would help. Drilling can be to approximately 1/2 way
through the timber, or, all the way until soft wood is encountered. And
yes, they would be used for the introduction of both the CPES and the
L&L resin. However, the CPES should be generously brush/spray applied to
all accessible surfaces as well, allowing the wood to absorb all that it will.
Since the bottom of the sill beam is rotted, you're going to quickly
start to lose CPES into the ground. However, it will also penetrate
horizontally into the deteriorated wood. So, we suggest doing a deep
flood of the drilled holes initially, that is, filling them completely
several times in a row to allow lateral migration of the CPES into the
bad wood before the excess is lost into the ground. Losing the CPES into
the ground isn't going to do any harm, though, since it will impregnate
the dirt with epoxy and make it very unattractive to insects, fungi and bacteria.
Website suggests wrapping in kitchen wrap to prevent L&L
from flowing out -yet the worse parts are underneath - how
can I wrap that?
You are going to wait for at least several days (or longer) after the
application of the CPES before you begin infusion of the L&L Resin, and
to some extent the CPES will help seal off the ground. We'd suggest
making the first infusion of the L&L Resin a fairly light one, so that
it drops down and builds a bottom layer. This will cure hard in 24 hours
and should then provide a base for the application of the rest of the resin.
When you wrap the sides of the beam with the kitchen-wrap and pour in
the resin, you should see within 10-15 minutes some indication that the
resin is flowing to the sides. If not, then you can assume you are
losing resin somewhere. If the inside of the beam has cracks/holes or is
porous, then that would be a place for resin leakage.
An slight alternative here, if you suspect that you might lose resin on
the inside of the beam, is to make your first L&L Resin application one
that has the fine sawdust mixed in with it to add bulk. The mix should
be pourable, and allowed to settle down, cure (24 hours), and then you
can proceed with the rest of the fill. These are conditions we often
face in marine reconstruction, so one has to be intuitive -- kind of
like a dentist drilling into a bad tooth.
If the weather is hot during this process the L&L Resin will tend to
cure much more quickly. We suggest mixing the resin at 70's temperatures
and getting it into the wood as quickly as possible. In hot weather we
often pour early in the morning when temperatures are a little cooler.
Can I spray CPES with cheapo plastic spray bottles that
are disposed of afterwards?
Yes, as long as the bottles are intended for insecticides, that is, from
the garden-area of the local home store.
We're architect & engineer and are aware that we need to
stabilize this, but will be looking for practical cost-
effective ways for this test project.
Good analysis! Good questions! It's a kind of tedious process, but the
result is a VERY hard and structurally sound repair. Once done, the
repair will be virtually indestructible.
Come on back if you have additional questions.