Integrity of water soaked wood structure 2

[Brunelwannabe]

Wood members can get wet and still be useable but what level of soaking (and some drying) is reasonable? This is particularly relevant in the wake of Hurricane Charley.

 

[epr]

Brunelwannabe,
First of all, that's an interesting handle. Are you an afficionado of engineering history?

In response to your question, when lumber is used in a wet state, the allowable stresses are slightly less per the NDS (Table 4.2 in NDS), which means that if the lumber is not heavily loaded at the time it becomes saturated, it may be no big deal.

When the lumber dries, the allowable stress is generally back to the original, unless it had become damaged while wet. But the wood may suffer some distortion due to the wetting and drying process, so be prepared.

However, this fact is not applicable to glued members, such as plywood, glulams, PSL, LSL, I-joists, etc., as the saturated condition may deteriorate the properties of the adhesive and may render it considerably weaker, swelled in volume (likely unevenly), and possibly unusable.

An interesting fact that you might appreciate: In some older, wood-framed buildings where some of the lumber has developed a "set" due to long term, high-stress conditions, the wood can be saturated repeatedly, and jacked after each wetting, and the "set" can sometimes be reduced to reasonable levels, such that structural renovations can be accomplished more appropriately. (Of course, this is an entirely different discussion.)

 

[boo1]

EPR has a good post. But be carefull of OSB sheathing strength loss from flooding. Damage due to differential swelling can reduce the sheathing strength.

This is the link to the Plywood Association, who should be quite familiar with your problem.

http://www.apawood.org/