Shrinkage Western Red Cedar

[Heart Wood]

I'm planning my very first full scribe log shell project to begin this spring here in NW Indiana and would like to know how much  shrinkage to expect from Western Red Cedar logs. Log will be approx. 18 inches at butt end and about 10- 12 inches at top. Moisture content will be about 20% when I start notching.  Log shell will be 32 x 40-0 Has anyone used Western Red Cedar or know some thing about how much it might shrink? The height will be 9-0 feet.

Thank,
Heart Wood

[catspa]

Hey, HW.

About 6 years ago I was on a crew that built a 24x32 cabin out of WRC logs in far western WA. It took the owner almost a year to select and buy the logs, because a lot of WRC trees here either curve or have excessive butt flare. But anyway, he got 'em, and they varied from about 12" to 22". Being the finish carpenter, I was assigned to floating window and door frames, which I slotted into the stack.

I allowed for 5" of headspace, and the first two years took up about 3" of it. The next three years took about another inch, and I noticed about 6 months ago that they were about 1/4" lower. So I feel pretty good about my initial 5" guess, and I think it's settled most of what it's going to.

HTH, Parker

[jfl]

Hi,

I can't give any practical figures, but you can compute the shrinkage from data of chapter 3 of:

http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/fplgtr113.htm

jf

[SwampDonkey]

Western red cedar has a green specific gravity G_g = 0.31 , Vol shrinkage V_sh%= 6.8 %, radial shrinkage R_sh% = 2.4 %. You say MC = 20 % when you get them.

Need to find fibre saturation point (FSP).

FSP = V_sh%
          G_g
      =  6.8 %
          0.31
      =  22 % (rounded)

Now calculate partial tangential shrinkage from 20 % to 12 % MC or for the situation where your timbers will be used. Might not be as dry at 12 %.

20→12
R_sh = 2.4 % * (20 % -12 %)
         22 %
      = 0.87 %

Assume 14 " for middle diameter of log.

Shrinkage of 14" log = 14" - 2*(14" x 0.87%)
                                                   100
                                = 14" - 1/4" shrinkage
                                = 13 and 3/4"

9 feet = 108"

108" / 14" x 0.25" = 2" shrinkage in the stack. As a general rule however I think 1/16 per 2" is allowed for. So that is close to 1/2" for a 14" log, so the stack will shrink 3.5"-4", might be some settling in the building occurring as well. Depends on how tight the logs fit together in the stack. Wood doesn't air dry uniformly either.

catspa, how high was your walls? Sounds like a good allowance.

[catspa]

Yeah, my stack was about 9-1/2 feet. Tried for about half an hour to insert a pic, finally gave up, but the end logs run out 10 feet or so long to support the porch roof.

Parker

[Jim_Rogers]

Tried for about half an hour to insert a pic, finally gave up.......

There are plenty of instructions here on the forum about how to insert pictures into your posts.
First of all you have to create a gallery here on this forum and upload them to it, then you can insert them into your posts...

And by the way, welcome to the forum.....

Jim Rogers

[Jeff]

Note: To post photo you need to have a recent version of Java on your computer. Most all computers have java installed You can download or upgrade java here:
http://java.com/en/
UPLOADING

1: Open post box, under post box you will see this text and a link:

Upload or insert Photo?
Click on Java Uploader (re-sizes for you)

2. Click on Java Uploader (re-sizes for you) to open a new window.

Wait until the page completely loads. If you have any trouble with the page completely loading, you need to update java.

3. Choose an album or create and choose an album at this time.

4 . Browse to your photo on your computer and select it.  If your photo needs to be rotated, you can do it at this point. Repeat if you have more then one photo.

5.Select upload. A re sized photo will be uploaded to your selected album.

6. At this point you can re title and describe and add key words to help search for your photo later on if you would like. if you change the title, click on the"apply modifications" button to set the changes.

ADDING PHOTO TO POST

7. Click on the thumbnail image to go to the full size image. Underneath the photo in the file information box, click on the link that says
"Click here to copy this photo code directly to your Forestry Forum post window"
This will add the code to your post box.  You can now go ahead and make your post.

Alternate method of adding new photos or previously uploaded photos to post if number 7 fails to add the code.

8: If the code does not appear in, just below the link that says Click here to copy this photo code directly to your Forestry Forum post window, you will see a text box with the actual code you need. Select, copy and paste that code in your postbox.

[Heart Wood]

Thanks Catspa I'm glad you have experience with WRC. Your calculations were good. I'll keep info. for future use.


Heart Wood

[Stephen1]

Welcome to the Forum! The rule of thumb for shrinkage is 3\4" per foot of stacked  log wall height. you can expect your walls will shrink for 5-7 years. http://www.logassociation.org/ Here is a link to the ILBA website. There was a nice lists of log building do's & don'ts when I built mine. Good luck and do not forget the pictures. :D