BENCHMARK

I had called as defective on a 48 yr old house. In my state Indiana wood floor joists 48 year old are Douglas Fir which is much slower to gain moisture out of the air. I don't think that very many inspectors know that wood gains moisture based on several criteria: relative humidity as opposed to humidity, species and percent of sapwood as opposed to heartwood. Southern Yellow Pine has been the species predominately used here for the last 35 years. It is highly absorbant and is primnarily sapwood which absorbs more readily than heartwood; way more! For these reasons Doug Fir, & older woods which often contain much higher percentages of heartwood can often handle humidity conditions that would rot yellow pine. These woods also change dimension less so movements from humidity changes tend to affect structures & floorings of these woods much less. 100% coverage is optimal not necessary in most situations. Several other people down the thread have affirmed this logical statement. I don't know where you got your specs on a vapor barrier but in some ways thery are understated & others over the top. Keep things in perspective & call it a ground moisture barrier. I inspected a house last spring which had just had a 'perfect' ground moisture barrier system installed a couple of weeks before I got there. The barrier was 10 mil & extended up the foundation walls to the top where it was fixed with a treated wood strip. By the end of the summer (an especially dry one) the walls in the house were cracking over the tops of interior doors & interior walls were 'wrinkling' the drywall tape where they met the exterior walls. These clients thought the house was falling in and almost called their attorney before me. (I may not be out of the woods yet) When I looked in the crawl, I found everything nice & dry, in fact the Yellow Pine floor joists were around 7% RH. They outer perimeter joists, covered on the inside of the crawl by fiberglass batts have a moisture content of 15%. I did not write down the moisture contents during my inspection, because they were inside the normal range & the moisture system looked 'perfect'! It is my opinoon that the whole floor structure, beams included, underwent a straight line drying which dramatically changed their dimension; with the outer perimeter joists drying less & changing dimension less. I installed crack monitors on most the the interior cracks & on two tight cracks in the foundation that were noted in the original report. Nothing has moved since October. I think the event is over but my clients are not so sure and they have a bunch of cosmetic repairs to make. The bottom line here is when there are yellow pine or other sap wood species floor structures in a crawl which has been very wet for an extended period; drying this crawl down is very likely to result in differential downward movement as the wood structures dry & shrink. This is more at the beams! It's making a lot of sense to me!

Permanent Wood Foundations (PWF) have been around for about 30 years. I have often heard inspectors say that they are only good for about 30 years if they are done correctly. The Southern Pine Council's guide though calls them permanent and gives no other longevity expectation. They do recommend coating exposed wood surfaces with pentrating sealers or stains. The thing is nothing is made perfectly all the time, installed correctly all the time or maintained regularly. I'd like to know if there is a guide to defects unique to PWFs. What kinds of defects are you folks seeing? Does anybody ever see decay or termite (WDI) infestation in bonifide PWFs? Does anyone pull a little soil away to expose surfaces just below grade? Let's get a thread going on this.

Thanks Jim! I really appreciate your time. My strong suite is structures. Call or write me if you ever want to 'bounce' something off of me. (812) 384-8914 benchmarkhs@sbcglobal.net

Mike: Obviously, I'm not being clear! I know that subpanels need to be grounded/bonded & that neutrals need to be isolated from grounding/bonding. Just reading the words "Article 250 – Grounding and Bonding Section 250.54 Supplementary Grounding Electrodes" does not clearly tell me that this is also the reference for or discussion of the requirement to isolate grounds & neutrals. Maybe it is but I couldn't tell. I'm sorry for bothering you. Please accept my humble apology and my gratitude for your generous wisdom.

Thanks Scott & Mike! I used the search engine to look for sub-panel grounding neutral & did get there that way. However, I don't see the code reference numbers in that email. Further enlightenmentis need, I'm afraid. I do appreciate all the volunteering of time that yo all put into this forum. Mark

Can someone give me the NEC reference numbers to the requirement for having a separate grounding conductor to a sub panel & the proper ground & neutral separation of the sub panel. Thanks a Million! Mark

I inspected a home with a rear venting gas fireplace, Friday. The vent comes out in a screened porch. It's more than 4 feet from the patio door. Can anyone cite what technically is wrong with this besides general stupidity?