Moisture, fungus, and weakened floor
Due to a water problem under our home, (which I’m beginning the landscaping fixes for now) there is a lot of fungus growing on the joists and plywood flooring under there. The previous homeowner laid new 3/4 ply over the old floor in a couple of areas of the house for reinforcement. A vapor barrier was also laid under the house. I suspect, however, that I need to do more than that to fix it right. I’m unlikely to try to tackle this myself, but would like to know what to expect of a contractor. What will likely need to be done to repair this damage? If the old subfloor needs to come out, how would they handle the parts that are beneath load bearing walls?
Where is the house located Russ?
*It's totally impossible to tell what's needed without being there; I've seen fungus and mold on sound wood and on totally rotten wood.Consider hiring a home inspector for a survey of the dimensions of the project. Some will give you a rough estimate of $ amounts, many won't, but can give you a good idea of the extent of the work needed. This will give you a basis for evaluating bids from contravtors.Watch out for the low bid.Bob
*Russ, sounds like a mess. Fungus on the joists? Are we talking fungal growth or mold and mildew? Do all the joists need to be replaced, or just some. Are you talking about replacing all the subfloor (and finished) floor? Do you have alot of mechanicals running through or under the joists? Crawl space (or full basement)? When was the house built? Dimension lumber(or engineered). Block or poured foundation /how thick? Joists sitting on foundation or on a 2x plate? If I were dong the job I would put in a temporary support wall or beam a foot or so offset from the existing beam(or wall) and allow the cantilevering joists to support the wall above while I replaced the joists on the other half of the house. Then do the same on the other side. I've made some assumptions about your construction in my answer, but this would be my first approach.Before you do anything, figure out how you are going to mitigate your moisture problem. The poly is a good Idea, if it isn't full of holes. Consider insulating the walls (1-1/2" thermax) taping the seams and taping the poly to the thermax, and then dumping some heat in there. Do you have humidity problems in th erest of the house? What part of the country are you in?
It is fungal growth, not just mold or mildew. The house is located in North Florida, a very humid, warm climate. The 2x joists rest on a block foundation. I've begun landscaping to mitigate the moisture problem which is caused mainly by a slope that drains into the foundation vents. I'm working to slope away from the house at least six feet from the foundation.
The house is fairly small, 1300 sq ft, and about half of the house is affected by the problem.
I know exactly what you have. I have done a bunch of these. If the subfloor is gone you have to take out finished floor and work it from the top. Haul in some fill while the floor is open and cover with poly. Open some more vents too. This is a different climate and humidity level than the cold frozen north.
Last one I did cost $30,000 and the owner said he would have paid more since an architect and a G.C each said it could not be fixed.
*Fungi can be a very serious problem relative to wood strength -- a 5% loss of weight can result in a 90% reduction in bending strength (MOE/MOR).Bleach is an effective biocide to kill the yeasties (molds, mildews and surface fungi). A borate application may also prevent re-occurance or another biocide like copper napthanate. You could spray these solutions on with a hand pump sprayer but you will need sufficient personal protection (skin, eyes, inhilation) especially regarding copper napthanate.Hopefully it is only a mold or mildew and that you are not picking mushrooms (fungal fruiting bodies) off the joists. If you are really concerned, you might find a local college or university (biology department) that will identify scrapings from the joists. Definitely increase ventilation and air circulation (ie a fan controlled by a humidistat). You may also want to determine the moisture content of the wood -- if it is less than 20% you likely do not have a fungal problem and it more likely related to surface growths of molds or mildew, which while looking horrific, do little structural damage. What ever you do don't panic yet -- I sense that edge in your "voice" -- and therein don't do anything rash. Identification by a qualified mycologist of the infecting organism(s) is definitely the first step. That procedure could cost you several hundreds of dollars but compared to $30,000 and the chaos of construction, it is a very small cost.Stanley
*Stanley,<>How does that loss of strength translate into hardness? I.e., can I poke it with my screwdriver and get some idea of damage/strength loss?MOE = Modulus of Elasticity?MOR = ??Any good sources for more info on this subject? On the Web?ThxBob
I read the haiku thread in the tavern, and this sprung to mind:
playful spring rain
flowing beneath cozy house
lightens my wallet
Due to a water problem under our home, (which I'm beginning the landscaping fixes for now) there is a lot of fungus growing on the joists and plywood flooring under there. The previous homeowner laid new 3/4 ply over the old floor in a couple of areas of the house for reinforcement. A vapor barrier was also laid under the house. I suspect, however, that I need to do more than that to fix it right. I'm unlikely to try to tackle this myself, but would like to know what to expect of a contractor. What will likely need to be done to repair this damage? If the old subfloor needs to come out, how would they handle the parts that are beneath load bearing walls?
MOE is the Modulus of Elasticity -- that is the elastic limit of the wood. Loads below this point are recoverable; beyond that point permanent damage (non-recoverable) occurs.
MOR is Modulus of Rupture -- The strength of the wood in bending.
Decayed wood is more brash -- The Dean of Wood Decay is a true gentleman by the name to Ted Scheffer who was still working, doing research and publishing papers (and occasionally riding his bicycle to work) at OSU at age 92. He (and only he) could use an ice pick to determine the brashness and therein determine if decay was present. For us mere mortals, that testing would be impossible.
I can think of no singular reference source that covers this -- it is likely spread out in hundreds/thousands of books, journal articles and papers.
It is reasonable to assume that hardness is likewise affected but with the variability of wood properties (especially density), a 5% loss in weight is more than likely within the normal range of weight/density. As such I would not consider it to be a reliable test.
I return to my original recommendations -- get the organism(s) identified by a mycologist. Make some MC determinations of the joists and subflooring. My first GUESS, based on the information provided, is that these are molds and mildews and not fungi.
PS The haiku reminds me of a very bad joke -- Why is there so much water in watermelon? Because it is planted in the spring.