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Re: Wood Beam Repairs

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Antonio S. "Tony" Luisoni wrote:


>Existing (30 years) Balcony, DFL 4x12 beams (exposed,  with redwood spaced
>1x6's) , cantileverded (with back spans into the building). Front prtopn of
>beams have severe dry-rot damage.
>
>Suggested repair: Cut offf infected portion at a 45 deg angle, add new
piece
>of 4x12 glued to existing, add 2x12 both sides (full cantilever length) and
>staggered bolts.

>[Bruce  Pooley response  - this repair is appropriate except that I think
you should attached the 4x12 wood filler pieces using nails or screws.
Galvanized nails or "deck" screws would be preferrable. Gluing would require
additional labor and chances are that it will not bond satisfactorily.]



Questions: a) What kind of glue should be used (4x12 to 4x12) ?

[ Bruce Pooley response - I recommend not to use glue (epoxy) since it
requres additional labor and cost and does not add to the intergrity of the
repair.]


b) How can I prevent the added 4x12 and 2x12's from future
dry-rot ?

[Bruce Pooley response - use pressure preservatively treated wood. I would
recommend Southern Pine with CCA treatment or other waterborne treatment.
They are available at most lumber yards or home centers such as Home Depot.
Southern Pine accepts treatment much better than Douglas Fir. A  Southern
Pine 2x12 will probably be fully penetrated and therefore not subject to
interior decay such as may be the case with Douglas Fir that has only
minimal penetration. (I recently rebuilt a deck on my home and used SP 2x12
for beams and 2x10 joists.) Cut the ends of the 4x12 and the added 2x12's
back at a 45 degree angle to prevent absorption of rainfall in the end grain
of the 2x12's.]


c) Do exposed Parallams or Microlams resist dry-rot ?

[Bruce Pooley response - my understanding is that Parallam (R) and Microllam
(TM) are not recommended for exterior use where they are subject to direct
rainfall. You may want to contact Trus Joist MacMillan (Chino CA office
phone 909-627-7331) or other manufacturers of parallel strand lumber (PSL)
and laminated veneer lumber (LVL) such as Georgia Pacific or Louisanna
Pacific. LVL and PSL are not typically pressure treated. If you use a "paint
on" preservative, a yearly maintenance schedule will need to be implemented
to prevent future decay of the wood members.]


Bruce Pooley, P.E.
Timber Design
3448 South Newland Court
Lakewood, CO 80227
phone 303-989-8701