Field Guide Wood Inspection

[marinaman]

Does anyone know of a good field guide, with pictures, for inspection of wood structures?

I was observing a structure yesterday that has white and brown mold or fungus on the surface of 2x10 wood roof joists. I do not know exactly what this is, nor, how damaging it is.

A field guide would be helpful.

 

[bridgebuster]

I found this US Navy publication in my files; perhaps it will be of use to you.

 

[MacGruber22]

Sounds like maybe the roof is not being vented too well.

One in the hand is worth two in the bush.

 

[KootK]

Link. From the good folks at the forest products lab.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[marinaman]

Thanks guys. I appreciate it.

I've attached a photo as to what I'm looking at. I'm looking at a roof area that's only about 15' x 10' at the top of a bell tower. The joist were once subject to a lot of moisture, but now, the roof leaks have been stopped and the wood has dried back out. I took several moisture measurements and found the moisture content between 10% and 12%. The wood was hard.....it was not spongy.

I'm thinking that most of this decay is surface only. I'm thinking that the decay stopped when the moisture exposure was stopped. This structure is more than 125 years old, so I am not wanting to modify much of it if I can help it. I'm thinking that I may have them clean off the fungi/mold, coat the wood in an anti microbial, and then just have the owner monitor it over time.

 

[dhengr]

Marinaman:
Well..., you are trying to determine if there is significant decay, right, surface or otherwise? And, you can see some fungus and mold on the joist and floor board surfaces, caused by moisture. I’d take an ice pick or a thin screw driver and pick around a little to make sure that the wood is solid on its interior. I would particularly look at the bearing points of the joists for significant deterioration. Has there been any relative movement (particularly vert. movement) btwn. the joists and the blocking btwn. the joists? That is, settlement of the joists due to bearing loads and rot, w.r.t. the lightly loaded blocking. You might look at the deflection of the joists with a string or some such, to see that this is not excessive. You might also have mold removal done, or just do something as simple as spraying the wood a few times with some chlorine bleach, or some such, to settle the mold down a bit. If you’ve stopped the roof leakage, you’ve probably pretty much solved the problem. And, you might also consider venting that attic space in some way so there isn’t a humidity build-up in the future. Churches aren’t usually likely to be too humid, but there might still be some heat and moisture vapor movement up into that space from below. Do something to minimize that moisture/heat movement. You might have to heat tape that roof drain.

 

[OldBldgGuy]

Read the US Forest Service Wood as an Engineering Material handbook (google will find it for you). Wood loses significant strength before it loses significant hardness. An awl is a handy tool to find really bad material when it doesn't look bad, but if you can see evidence of mold, fungus, or decay you can pretty well rest assured that there is a big problem. Unless the members were well oversized to start with, replace them.