Quantcast Evidence of Decay - mo111_10048

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4.1.3 CHECKS AND SPLITS.  Because glued-laminated arches are made
up of relatively thin members that have been individually dried, checks and splits
are much less common than in the larger timbers used in trusses. They would
usually be limited to one lamination so their effects would be minimal. Where
they do occur, the guidelines presented in section 3.1.2 would apply.
4.1.4 SPECIAL CONNECTOR PROBLEMS.  Tightness of connectors
should be visually observed as discussed under procedures. Also look for any
sign of movement of the connector relative to the wood member. Such move-
ment would result in splitting or crushing of the wood by the connector and would
require a rating of 40 (Fig. 3-5D). Connectors exposed to rain. condensation,
or other wetting may provide entry for water into associated wood and create
a decay hazard. Any decay in the connector area would rate 40, or lower if
displacement of the arch relative to the connector had occurred.
4.1.5 EVIDENCE OF DECAY.  The same general principles of decay
apply to glued-laminated arches as discussed in section 3.1.4 for trusses. One
difference is that arches often extend outside the building with the ends beyond
the roof line and resting on concrete abutments. These ends are not only exposed
to rain but also the drying effects of the sun which can produce deep checks
that are traps to catch water. Such checks as well as delaminations are especially
susceptible to decay unless the wood is preservative treated.
Follow the procedures listed under section 2.2 to examine for decay. Special
attention should be given to three areas: (1) The arch end region immediately
at or above the base connection. This is the most susceptible area for decay
because of water entrapment behind the metal collar and wetting of the end grain.
(2) The exterior exposure just outside of where the arch penetrates the building
wall. The concentration of water running off the roof as well as the joints at
the wall interface around the arch has a high potential for trapping water. (3)
The crown of the arch where two segments join. Although thus area is protected
by the roof. any deflection may cause water ponding on the roof. Also. indoor
water vapor may condense at or above the arch, particularly in high-humidity
buildings such as those with swimming pools.
4-2





 


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