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Corrsion of Fasteners in Treated Wood
By Edward Robinson | June 11, 2008
Table of contents for Look At This!
- Look at This Brick
- Corrsion of Fasteners in Treated Wood
- Creative Structural Repair
Corrosion of steel structural connectors such as hangar straps or nails can be a significant issue when using treated wood for structural members. The use of treated lumber is common in crawlspaces, decks, and equipment supports in my area.
Recently I have seen significant corrosion at connectors and their nails in construction using treated lumber. In some cases corrosion could be observed which appeared significant even where galvanized connectors were used where construction was relatively new. This is concerning because if the corrosion progresses and causes failure of the connectors then failure of the structure could follow.
Some manufacture of connectors recommend the use of stainless steel components when a structure is constructed of a corrosive treated lumber and is in a high moisture area such as a crawlspace or wet service application such as a deck. This recommendation does not have to be followed if the engineer of record for the design of the structure does not specify the connectors, but the engineer takes responsibility for that decision and can be questioned on it if you have concern. If you have a question on whether the correct connectors have been used you should always check with the engineer of record or the engineering department of the connector manufacturer to determine which connectors were specified or required.
Another consideration is how a structure is constructed. I have seen cases where structure at a raised floor system or condensing unit support platform rely on the strength of the fasteners for support. The concern for ultimate failure of a structure can be reduced if interference loading, such as lapped or notched members, is used between members rather than relying on the fasteners. When evaluating such structures such concerns should be considered.
I would encourage you to spend some time on reviewing the latest materials on the subject of corrosion resistance in structural applications for wood materials. The literature seems to change periodically as the methods of protecting lumber change and the methods of protecting metal connectors are found.
Some good Resources for review are:
http://www.strongtie.com/productuse/ptwoodfaqs.html
And Downloadable Document(s) at:
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