Moisture Control

Question: 

What are the health hazards of black fungus on Douglas-Fir lumber?

Question: 

I am looking for some information regarding black surface mold on lumber. Does it alter the integrity of the lumber stress values? I have a client who wants to use “all dry” lumber for his construction but I do not know if this is really necessary.

Question: 

I would like to know if there is an age restriction on wood trusses. How long after production are they safe to use? The trusses in question are at least three to four months old. Are they still safe to use? They have not been covered the entire time and are showing signs of age.

Question: 

Is lag bolting the bottom chord of a truss to the top plate of a wall a proper fix to correct truss arching, assuming the attic is properly vented?

Drywall cracking and ridging are typical problems seen in ceilings and walls of homes. Sometimes, both of these issues appear at the same location, with cracking appearing in wetter months and ridging in drier months. This problem has become more widespread as homeowners insist on larger rooms and open floor plans that have large clear span areas. This Research Report evaluates local environment changes that play a significant role in every gypsum ridging and cracking case.

A truss designer who recognizes conditions that require a reduction in lumber or plate design properties can help ensure trusses perform as the building designer intends.

  • Standard metal connector plates are suitable for use in lumber with moisture content of 19 percent or less and in building applications with no exposure to corrosive substances.
  • Connector plates used in trusses exposed to high humidity or caustic chemicals may need to be treated to prevent corrosion.
  • A variety of protective coatings can be applied to truss places in situations where special protection is necessary.