Seacoast is a full service inspection company. We offer home inspections, residential and commercial thermal imaging ( Infrared ) , Blower door testing, Energy Audits, and Property Condition Assessments based on ASTM 2018-08. Our home inspections are performed by MA licesensed home inspectors. We serve most of New England and perform home inspections in MA, ME, and NH.
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Terry's Tips are personal observations based on my experience and seeing the cause and effects of things. There may be many ways to address different problems and all opinions are welcome. I am always open to suggestions and certainly want you to correct me on any mistakes that might be written.
If you look and listen to your house, it will talk to you. Are you listening?
Here we see a galvanic reation taking place which is causing the corrosion. The large headed nails appear to be electroplated roofing nails instead of the hot dip galvinized 10d nails used on the joist. You can clearly see the performance difference. Roofing nails do not provide the proper shear strength to be used in joist hangers anyway. This is a safety concern on both fronts and replacement is needed.
With today's ACQ lumber it is highly recommended to only use hot dip galvinized  fasteners or better yet stainless steel.
Resources: http://www.safestronghome.com/deck/02.asp
Galvanic reaction on joist hangers