Sistering moldy joists or just replace.
holy hammer
| Posted in General Discussion on
I spent two hours in a crawl space today with a highly respected engineer looking at moisture issues. The moisture content of the wood was 36%. Some joists were 100% saturated and had visible deterioration on them. There was major fungi growing on the wood. I opted for replacement of the damaged mold covered joists, but the engineer said to sister them with treated pine. It was the only thing I disagreed with in his report. I have in the past taken out anything extremely moldy.
We will probably seal off the crawl space and install a dehumidifier after the repairs to the framing. I am in Coastal SC, the humidity capital of the world.
Should we sister or replace?
Constructing in metric…
every inch of the way.
Replies
See Photos of offending joists.
Constructing in metric...
every inch of the way.
IMO, if you sister a new joist next to the old, moldy one, you're just going to accelerate the mold growth on the old wood. Trapping that moisture in there isn't going to help. I'm not sure how much a dehumidifier is going to help. It may keep more mold from starting, but unless you get the humidity down quite low, its not going to help with what's there.
Unless you run the new joist from bearing point to bearing point, at some time, when the old joist rots and falls apart, the building is going to be worse off than it is now.
Shep, The new joists will be on bearing points on each end and steps will be taken to reduce the humidity levels to achieve 16 to 18 percent moisture content of the joists. As far as the dehumidifier, we will remove the insulation,seal the crawlspace and place a dehumidifier to pull out any moisture. They call them conditioned crawlspaces around here.Constructing in metric...
every inch of the way.
I'd still be concerned about the face of the old joists sistered to the new. I don't remember at what % humidity the mold stops growing, but trapped between those 2 pieces of wood makes good growing for it if the humidity is right.
Bad mold types usually don't grow at moisture levels under 20%. I am concerned too. The engineer didn't seem too troubled by it though. That's my dilemma. I am a perfectionist and I don't want the old yucky wood left in the crawlspace. Chances of something going wrong will be greater if the old moldy wood is left. I just have to convince the homeowner of this even if it is contrary to the engineers written report. I also have to justify the increased cost.Constructing in metric...
every inch of the way.
Where you going to get special mold to wood glue? Sounds a little crazy to sister to this mess.
I would pull the floor and joists. Fix the damp floor reason. Then install new treated. You could air dry this before install to reduce some of the "new" damp.
I know this isn't the same thing but, ask the engineer if he would place his male member up against a highly contagious male member, even in a "controlled environment". Chances are it would be no. Probably even HHHHEEE, EEELLLL NO. if it were my home, I would want the bet possible solution out there. And that's probably what your clients hired your for. Tell them that the inspector says "this", but I highly recommend "this". If they agree with the inspector, it's on them IMO. But make sure they sign off on it. :)
I wouldn't want to leave any of the old moldy joists there, but have you thought about how you are going to fasten the new joists to the subfloor when all the old ones are gone?
depends why they are wet in the first place to some degree.
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
I just noticed yesterday that, along with the usual insulation blower/floor nailer/lock borer stuff, my local full-service yard rents out a mold fogger.
I don't exactly know what that is, but I can guess.
I'm wondering if a fogger might work best at the current high humidity levels, which would retard the drying of the mildewcide (or whatever agent it uses), and allow full saturation of the space.
I've used a Quat-based mildewcide before, very potent stuff, use about 1 oz/gallon. I got it at a janitorial supply house that I trust -- there was no equivalent off-the-shelf product in the stores.
But I wouldn't want to be crawling around using a garden sprayer over my head in a confine space.
So my advice to you is...
"Get Fogged!"
AitchKay
AitchKay