Replies

1. 
   terrylee86 | Dec 01, 2006 02:16am | #1

   I don't think moisture content is an issue for your application.  The two woods you mentioned are not very rot resistant, but you say they will be protected by the porch and not get rained on very often.  You don't need to set them out side to gain moisture.  Build the benches accounting for expansion and contraction of extreme enviornments and put a good primer and exterior house paint on them and you will have years of service.  If you are planning on a clear finish I would choose other woods. ( teak, ipea, even white oak or cedar)

1. 
   DHAM | Dec 02, 2006 12:09am | #2

   The kiln dried wood will absorb moisture from the environment and will re-equilibrate somewhere between 12 and 18% depending on the season.  Therefore, the wood will swell.  Say the wood is KD at 7% now.  You need to calculate the amount of expansion that will occur as the wood moves from 7% to say 18 or 20%.  Then, incorporate this amount of expansion into your design.  The other option is to sticker the wood that will be used under a roof, but exposed to the outside air like an open shed or porch and let it gather some moisture and equilibrate before building the projects.

1. 
   terrylee86 | Dec 02, 2006 12:45am | #3

   I agree with you in concept,but unless you keep your lumber in a moisture controlled environment ( dehumidification, heated, air conditioned) it will reabsorb moisture to equalize to the surrounding environment.  I have never bought any lumber that has been out of the kiln for longer than a month that is 7% in Michigan.  I have a Wagner moisture meter(#220) and I test all my lumber at the dealer and in the winter it is lower and in the summer it is higher.

1. 
   DHAM | Dec 02, 2006 03:33am | #4

   I think that you were right on the mark in your post when you said to base the design on the lower and higher extremes. If the benches are to be brought inside sometimes and left out sometimes and they are well finished, they will not likely change moisture too fast, but over time, depending on how long they reside in or out, they will see the full swing of equilibrium M%'s from 7 or so inside in the winter to maybe 18 outside in the summer. Using a shrinkage calculator, you can determine the maximum amount the wood will shrink and swell and allow for that amount of movement plus a little extra for insurance. On a bench, it should not be too tough to design for that.

2. 
   thebige | Dec 02, 2006 08:11pm | #5

   Hello again, Thank-You all for all your help. I kind of thought somewhere around 12% or so.

3. 
   81treehouse | Dec 03, 2006 07:24am | #6

   Titebond III

    

   A bad day woodworking is better than a good day working -- yes, I'm retired!