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The Daily Fix

Today's Wood Products are Easy for Mold to Eat

Official Fine Homebuilding Post, editor

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As wood goes through the refining process, susceptibility to mold increases.

As wood goes through the refining process, susceptibility to mold increases.

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by Joseph Lstiburek

Refining wood makes the mold nutrients more accessible to mold. As we go through this refining process, we also switch to tree species that are high in sapwood content and make them more susceptible to mold.


Solid lumber

Even young, violent mold with a bad attitude can’t get the sugar from old-growth timber-frame structures. That’s because most of the lumber is heartwood cut from species like Douglas fir, white pine, and white oak. Mold can live on a sapwood surface, but it doesn’t like the heartwood that’s common in old buildings.

Sheathing

Rather than cutting the tree into 3⁄4-in.-thick boards for sheathing, we now peel the tree and smash the layers together under heat and pressure. This heat and pressure caramelizes the wood sugars into mold candy, or plywood. We also flake the mold candy and put the flakes in a vat to make oriented strand board. OSB is the Spam of mold food. Because we peel and flake the tree, we can use smaller trees that are faster-growing and contain mostly sapwood. If you’re mold with the choice between 2x4s and OSB, which are you going to choose? OSB, every time.

Particleboard and MDF

We take those candy fibers, and we grind them down to make sawdust. Then we add nitrogen to make particleboard (the nitrogen is like Cajun seasoning for fungi). We make furniture, cabinets, flooring, and underlayment from this. If you’re mold with the choice between OSB and MDF, which are you going to choose? MDF, every time.

Paper-faced drywall

Finally, we grind the sawdust and reconstitute it to make nature’s most perfect mold food: paper. Old mold with no teeth can eat paper. We glue the paper on both sides of drywall and wrap the insides of buildings with it. On commercial buildings, we wrap the outside, too. Even the dumbest of the three little pigs didn’t build his house with paper. Sometimes we color it green to fool the mold and put it in the shower. We glue tile to the paper, and we hose it down with hot water twice a day. Unless you’re mold, repeat after me: paper, water, bad.

Read the complete article... The Mold Explosion: Why Now? Today's houses make it easier for mold to thrive. The cure is quick cleanup and smarter choices in materials. by Joseph Lstiburek

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