| Whether you have a small crack or a large
crack in any structural framing component, you have a problem. The
larger the crack of course, the larger the problem.
In the picture above, the crack is hardly noticeable. The darker spot on
the wood is actually a small knot in the roofer rafter and this one
isn't very big. Just like the size of the crack, usually the larger than
knot, the larger the problem can be.
This crack was caused from excessive structural weight directly above
this roofer rafter. The builder or engineer should have called out for a
larger sized roofer rafter, for example: I would've installed 3 - 2 x 6
roof rafters and nailed them together.
There are a few different things that can cause small cracks and one of
them is old lumber, as lumber ages, the moisture from the wood will
start to evaporate, causing the lumber to shrink.
If you live in extreme climates, where temperatures fluctuate from hot
to cold, for example: during the day, temperatures are reaching well
over 100° and in the evening, they're dropping below 40°, these
temperature differences can cause the wood to contract during the day
and absorb moisture in the evening, causing them to expand.
Over time you will have small and large cracks in your
wood. Small cracks can also be caused by excessive weight over an
individual framing member and lumber defects.
Home Repair Tip: Install another 2 x 6 roof rafter
along each side of the cracked and damaged rafter. Make sure that you
nail the three rafters together, using 16-D nails and stagger nailing
them every 16 inches.
This is only a recommendation, you should contact a licensed building
professional to evaluate a situation like this.
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