I'd like your advice on wood expansion

I am making a cover from teak to cover the mantle on my fireplace. The current mantle is really ugly piece of blue stone. The teak will match a teak entertainment center I built a year ago. The mantle will be covered on all sides. The mantle is 74 1/2". This is in a vacation home in New Hampshire. It will be down to about 55 degrees in the winter and maybe 80 degrees and humid in the summer.
OK, that was the long slow windup. Here comes the pitch. How much room would you leave for expansion? The side pieces will match up to some trim where the chimney and the wall meet so I can't just make it as wide as I want.
Your advice would be greatly appreciated.
Dick Snyder
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Not enough information. Look at http://www.woodworkerssource.com/movement.php
For how to estimate
--
Alex -- Replace "nospam" with "mail" to reply by email. Checked infrequently.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 10/25/2012 3:10 PM, Dick Snyder wrote:

Relative no length expansion and or thickness expansion. The only expansion that you will notice will be in solid board widths. Leave yourself a bit of wiggle for the boards to expand and contract in width. On a 12" wide board I would suggest as much as 1/4" wiggle room. This may not be an issue if the width/edges of the board are not between two fixes surfaces. If one edge is not confined there should be no issue.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Thanks. The widest board will be 7" x 74 1/2". I was most worred about length but I do have room on width as long at I place the two end pieces, which will be at a 90 degree angle to the long boards, with screws in oversized holes so the long pieces can move.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Thu, 25 Oct 2012 18:30:48 -0400, Dick Snyder wrote:

Movement along the length is almost non-existent. Your end pieces are "breadboard ends", lots of info out there on those. Depending on the finish, 1/4" per 12" may or may not be enough.
Dewaxed shellac or oil based polyurethane do the best job at slowing water vapor from moving in or out of the wood, but nothing will stop it.
--
When fascism comes to America, it will be wrapped in the flag and
carrying a cross.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Thanks Larry. I will just be using teak oil on this project so it matches the entertainment center I made.
I think the breadboard ends idea will work well. Of course this isn't exactly a breadboard with an end piece attached to the main breadboard. My breadboard will be two pieces of teak sandwiched over a piece of bluestone. The breadboard end will be just over 3" high and will have to be attached to the top and bottom boards of the sandwich with a tongue and groove. It will will allow me to hide the mechanical fasteners on the top and bottom of the boards that will hide the existing mantle. I can cut plugs so even the screw heads won't be seen easily. I suppose I could even make teak dowels but I think screw heads hidden by plugs should work well on this project.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

On a 7-inch-wide board, you might see as much as 1/8" difference in width; thickness changes at about half the rate that width changes, so if the board is 3/4" thick, you'll need precision tools to measure the change in thickness. And the change in length is effectively zero.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Thursday, October 25, 2012 7:32:45 PM UTC-4, Doug Miller wrote:

Does that hold true for flat, quartered and rift sawn boards - or just flat/plainsawn? I haven't heard that before.
JP
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

It depends on the species, of course -- 1/8" over 7" is an average estimate for plainsawn lumber. Quartersawn should be about half that much, and riftsawn in between.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 10/25/2012 5:30 PM, Dick Snyder wrote:

Every woodworker needs to keep a copy of the following in the shop:
http://www.fs.fed.us/ccrc/topics/urban-forests/docs/physical%20properties%20and%20moisture%20relations%20of%20wood.pdf
As you will read, not only is the species of importance when selecting woods based on their reaction to moisture/seasonal changes, but also the cut off the log (quarter sawn, flat sawn, etc).
As a general rule, and for most species, if you want to reduce expansion and contraction across your board's face, try to select quarter or rift sawn stock for those areas/components which may be subject to dimensional instability due to moisture/seasonal changes.
(NOTE: these tables come in extra handy when you are faced with veneering/laminating different species of wood)
--
www.eWoodShop.com
Last update: 4/15/2010
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Thu, 25 Oct 2012 18:35:08 -0500, Swingman wrote:

20properties%20and%20moisture%20relations%20of%20wood.pdf>
Thank you - excellent reference.
--
When fascism comes to America, it will be wrapped in the flag and
carrying a cross.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Woodworkers may find this tool handy as well: http://woodshopwidget.com /
There are iOS and Android versions for $4 as well as a free web version.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.