Henry Asks:
Any idea about the useful life of 1/2″ steel bolts holding a pressure treated bottom plate of an exterior deck to the top of a concrete wall? Some of the bolts will never get wet – they are under a deep porch – some may get a little wet – this is the pacific northwest. If it is not critical I’m inclined not to rip the whole deck apart and replace them. Simpson’s info seems to indicate that half inch or greater has a long enough life. But Simpson’s main job is to sell their products and avoid liability so I’m not sure that I entirely trust their opinions. I’d rather have the opinion of someone with experience and no bias.
Thanks for your help!
Henry
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Thought you might find this Simpson article on corrosion useful.
Thanks for your email Henry,
First off, did you originally build the deck yourself, and do you know for sure that they are “Steel,”-meaning Stainless Steel? Stainless Steel bolts would be the recommended type for a coastal area such as yours today. Even though the bolts are protected from direct weather, moisture from rain, fog or windy conditions can affect hardware on an open porch.
Their are so many different types of bolts that it is hard for me to determine. Were these half inch bolts set in wet concrete, like an anchor bolt-typical with this type of construction or perhaps a wedge type bolt that was drilled in hardened concrete then bolted in place later on?
In typical framing situations, a PT bottom plate or sill is secured to a concrete foundation with steel-non-stainless steel anchor bolts that were set in wet concrete. These type of fasteners are approved for residential use in that the bolts are protected from weather by the exterior wall surfaces.
I am assuming that your deck is probably a two story affair. Deck hardware is particular vulnerable to moisture. These days, any deck hardware prone to moisture or salt, especially in coastal areas should be stainless steel. This goes for bolts, joist hangars, nails, screws etc.
You asked for an unbiased opinion, but that I can not give. I have been a long time user of Simpson Strong tie products for decades. They are the premier manufacturer of such products and have along and outstanding reputation in residential and commercial construction fields. They are always ahead of the curve in research and development and test their products extensively.
If you know for sure what type of Simpson bolts you have, you can also look up the ASTM requirements. For an independent look, see http://www.astm.org/. (All fasteners have an ASTM specification).
Assuming again, that your deck is raised or a two story affair, it would behoove you, to contact your local building department. Certain areas of the country have stricter requirements than others. I am also concerned that your attachment may also require some type of lateral support-meaning that you would not want the plate to lift and roll in case of earthquake or severe weather. In those cases, additional lateral support may be required. Though you may have stainless steel bolts holding down the plate, are your other fasteners stainless steel as well?
Whether a bolt or hanger, if you can see one, you can get the ASTM stamp off of it, then look up the hardware on ASTM or Simpson for more details.
About the only unbiased thing I can tell you, is that we always use 1/2″ diameter bolts for securing deck supports. In my area, galvanized bolts are sufficient. We have not had any issues with a 1/2″ bolt in our area, but have with 3/8″ and smaller.
Thanks for our question, Henry
Posted by Vinman | May 14, 2011, 11:22 PM