Steam and wood
Steam and wood
(OP)
I have a damage investigation I am investigating and part of the damage was due to a broken water line, part due to a broken water heater. The water heater put steam throughout the whole three story house over a 6 to 8 hour period before the leak was discovered. Apparently, condensed water was dripping off the exposed beams and walls, and the temperature in the house reached somewhere between 100 to 130 degrees F due to the steam.
My question is how long would you expect wood members to have to be exposed to the steam to induce significant swelling in the sections. Obvious damage was done to some members with additional spaces between the cardecking on the ceiling after it dried. Just trying to justify the physics here.
I am thinking that the cardeck expanded, closing most of any existing gaps, but when it dried, it did not reposition itself either back to the original position, or uniformly, opening up intermittent gaps between the members.
Anybody seen anything like this before?
My question is how long would you expect wood members to have to be exposed to the steam to induce significant swelling in the sections. Obvious damage was done to some members with additional spaces between the cardecking on the ceiling after it dried. Just trying to justify the physics here.
I am thinking that the cardeck expanded, closing most of any existing gaps, but when it dried, it did not reposition itself either back to the original position, or uniformly, opening up intermittent gaps between the members.
Anybody seen anything like this before?
Mike McCann, PE, SE (WA)






RE: Steam and wood
Back in the day when aircraft were made of wood (World War I or Howard Hughes' 1947 "Spruce Goose" - actually Birch) wood had to be steamed under pressure to raise the boiling point. Conditions such as 212+ degrees F, 20 PSI, for 12 or more hours were typical.
Even today the manufacture of plywood may use steam under similar conditions.
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RE: Steam and wood
Gaps will tend to open up due to drying. Most probably between installation and equilibrium some time after.
As-manufactured decking may be up to 19% MC, surfaced dry. In a dry environment maybe down to 5-10%.
Gaps may be non-uniform due to warping of the boards or restraint by the fasteners.
I don't think a short term air moisture would have time to penetrate the wood and cause volumetric change in the time stated.
I had gaps in my workbench open up to 1/4". I built it of cedar decking salvaged from a paper mill roof, where the moisture content could have been in excess of 30%!
RE: Steam and wood
RE: Steam and wood
Mike McCann, PE, SE (WA)