Rotten floor joists in crawl space - how much is too much

I recently bought a house that had significant moisture control problems in the crawl space [no vapor barrier! ] 70% of the floor joists and some of the support beams will have to be replaced due to significant rot caused by wood fungus and the high humidity condition.
However, some of the floor joists (2x10'sx 15' on 16" centers) have only about an inch or less of rot along the bottom - the rest of the wood is sound. If I treat those joists (with Borate, e.g.) can I save them? Will it pass inspection when I want to sell this thing? Or will an inspector say that they need to be replaced or sistered?

thanks........russ

 

Welcome to the forums! Remember your 2x10's have become 2x8's and their span has been reduced from 17'4" to 13'2", so they are undersized for your 15' span. Replacing or sistering is the only answer I can give, not being able to see the entire picture.

 

What did your inspector say before you bought the place?

 

I bought the place knowing the problems. No inspector used. However, Chandler brought up a good point. My 2x10's with 1-inch of rot or less have become 2 x 9's. If the max span for a 2x10 is 17'4" and the max span for a 2x8 is 13'2, then it would seem that the max span for a 2x9 would be around 15' (if we assume linear interpolation). Some of the spans are 13' 7" and some are 14' 7", so for the 13'7", I should be safe, but the 14' 7" are a toss-up. Ideally, I would like to replace all the joists, but there are reasonable guidelines that should be available to define what's good and what's bad. Thanks for the comments.

 

Have you ever tried to fix a "minor" rust problem only to find the metal damage far more extensive than it appeared? Wood rot is just like that.