Expert: Daniel Humphrey - 3/29/2010

Question
QUESTION: Hello, I am building a camp and using Eastern White Pine Timber 8x12 for the ridge beam and 6x8 roof rafters. I'm looking for the steps on how to proceed after the timbers are milled. I was told to have the timber kiln-dried for 3 weeks then planed and put oil on them, and also told to just plane them and dry in place (green). These are for appearance and I am trying to minimze as much checking as possible., also I'm using an 8x8 post to hold up the ridge beam in the center any recommendations on a bracket I could secure to the floor to put the post in. Thank You, Dick

ANSWER: Dick,

To minimize checking, seal all the end grain right away. If the end grain is not visible, you can use any kind of paint. I get "mistake" paint from the local hardware store for almost nothing. If it is going to be visible, coat the ends with whatever your final finish will be.

If you're living in a place like I live, you probably will not have access to a kiln, and the best you can do is let them air dry naturally after they have been put up.

I have had excellent results with the following procedure:
1. Coat all end grain.
2. Plane or belt sand visible surfaces with 80 grit.
3. Finish sand with 80-100 grit random orbital.
4. Seal with lacquer-based sanding sealer. I recommend Cabot's.
5. Sand again lightly with 100 grit after sanding sealer is dry.

6. You may do finish joinery and place the timbers any time after the sanding sealer is cured.
7. Clean up timbers in structure.
8. Coat with urethane. Water-based urethane is recommended, and you'll need at least three coats for outdoors. If you need the golden appearance, use an oil-based urethane or add a bit of amber pigment to the water-based urethane.

This treatment is generally good for about three years before some touch up is needed. Other log-home products have longer lifespans, and they can be applied over the urethane. Just the (unsanded) sanding sealer is good for a couple of months out in the weather.

You can do a variety of things to secure the post to the floor:

A. If on cement slab, drill a 1" hole and epoxy in a rebar pin that will go into the center of the post, and use a Simpson stand-off post base to keep the end grain off the concrete. http://www.strongtie.com/products/connectors/CPS-PBV_APG.asp
B. If you are pouring the concrete, embed a regular post base bracket. Use CBSQ for floors prone to flooding. http://www.strongtie.com/products/connectors/CBSQ.asp
C. On a wooden floor, I usually cut a pocket for a stub tenon. I provide solid reinforcement beneath. If uplift is possible, I use a floor bracket such as ABU88. http://www.strongtie.com/products/connectors/AB-ABA-ABE-ABU.asp

Hope this helps.

Daniel

---------- FOLLOW-UP ----------

QUESTION: Daniel, I have a place that will kiln-dry and a place to plane what are your thoughts about kilning.(Is it a waste of money? and does it kill all insect larvie and help minimize checking), also I'm looking to use Simpsons ccq88sds2.5 on top of the 8x8 post to support the (2)8x12 ridge beams(your thoughts). Thanks Again, Dick

ANSWER: Dear Dick,

The kiln drying will definitely kill larvae. Some pieces will check in the kiln, but the wood will be stabile afterwards and plane better. Personally, I would not make a special effort to kiln dry unless the client wanted absolutely no checking.   And then, I would put in a few more timbers so that I could select the ones that came out the best. One in four of our timbers up here will change dramatically during the drying.

That bracket might look good painted black. I do not use brackets for wood-to-wood connections, but rather make housed mortise on the beam and and a tenon on the post. Take a look at the joint and see if it appeals to you. If you want to try it, I can locate some instructions for you.

http://www.kennebectimberframing.com/images/joinery/Housed-Mortise-Tenon-with-re

Daniel

---------- FOLLOW-UP ----------

QUESTION: My (2) 8x12 ridge beams butt together and sit on 8x8 support post. Thinking of having both beams sit on one post. Thanks Dick

Answer
Dick,

Do you mean that they butt end to end, meeting over a post?

If that is correct, then yes, resting on the same post is the best.

I normally scarf those pieces together and offset the joint a few feet from the post, just to take some of the bending stress away from the joint. But without a scarf joint, you must support both ends with the post.

Here is an example of one kind of tabled scarf I favor, which keeps the timbers from twisting away when they shrink. I also glue these joints:

http://www.finehomebuilding.com/CMS/uploadedimages/Images/Homebuilding/Departmen

A simple lap scarf is better than just butting the ends together, and I recommend that at minimum.

Make sure you strap or spline those 8x12s very securely together if you do not scarf them.

The spline I'm talking about is made of 1-1/8" plywood, 6" x 24" and sits in a groove on top of each beam. Glue in place.

A metal 1/4" strap can also be inset, as a plywood spline, and bolted in. Or it can rest above and/or below the beam.



Daniel