i will be installing a new deck on the flatbed shortly, and am using oak planking. 1 1/2 inch X 5 inch X 8 ft
i am getting rough cut green wood from a local saw mill.
my question is, what will the shrinkage be on the 5 inch wide plank?

i kind of need the truck now, so would like to put the deck on green and let it shrink as it ages, but if it is going to be any more than around 1/16 inch shrinkage i am going to have to let the wood age/dry out befire installing it because the deck can not have any noticeable gaps in it.

 

hi Tom,,,,hope this can help you Measuring/Monitoring Moisture Levels

 

Tom,

"Oak" is a very generic term.
There are 16 species listed for North America.
For trees in your area preference is white oak over red.
There is a large difference in radial v/ tangential shrinkage.
You want your wood quarter sawn.

Being a wood geek, I'm sitting here opening the U.S. Forestry Service handbook 'Wood as an Engineering Material'

A lot will depend on the current moisture level.
Ask the sawmill what kind of oak and how wet it is right now.

I will assume an equilibrium moisture level suitable for NJ.... Unless you REALLY ARE in the exclusion zone.

 

Maybe the mill has a kiln to dry it, or has a connection to one?
1 1/2" oak is going to take years to thoroughly dry out.

And I'm talking about 12% EMC average for the area between Philadelphia and NYC , not bone dry wood used for furniture.
Northern Red oak is between 70-80% water when green
White Oak is 60-70%, but it has closed cells, so it absorbs and gives up water much more slowly.

Both Red and White Oak shrink about 4% radially, but White Oak shrinks only 8.6% tangentially where Red Oak is shown to shrink nearly 11% oven dry.

4% is 1/25, so you would expect a 5" wide quartersawn plank to shrink 0.20" (about 13/64)

 

^ ditto on quartersawn white oak. You can tell by the grain once you know what to look for. Oak warps badly otherwise.

 

99 .9% of our oak here is white oak, so i am assuming it is going to be white oak.
outdoor storage, and it is cut to order.
average turnover at the mill is 60 days, so it will be green. there is no kiln anywhere around here.
and i do not know the difference between radial or tangient.
the 1 1/2 is not the worry, the 5 inch is.
this is going to be the deck of a flatbed dump rack body, so it has to be tight.
i ordered 15 pieces for a total of 75 inches deck and have to fit it in 74 1/4 inch space.

a few guys on facebook said to expect around 1/4 inch shrinkage in the 5 inch side, so tuesday i am going to call and have them add another plank to the order.
then when it is cut i will just stick it in the rafters of one of the equipment shed on a friends farn to dry out until next spring.
in the mean time i will just cover the existing deck with 2 sheets of 1/2 marine plywood.
the existing deck is still serviceable, but it is showing signs of severe dry rot in a few places. i just want to replace it before it falls apart.

the plan for the oak is to sand the top side smooth and treat the complete boards with something like tongue oil before installing, then reapply once a year or so. i figure doing this will make it last forever.

 

Tom,
You already said what the truck is.
Radial means from the core to the bark.
If the plank is cut that way it will shrink and twist much less than if it is just sliced off the top of the log.
Yeah... about 1/4" shrinkage. My # is fifty thousandths less.

What are you carrying in this bed?

A NON-drying oil would stand up to wear better and not peel like a Tung oil finish can.
Much easier to re-apply too, since there's no sanding needed between coats.

Be sure to saturate the hell out of the end grain before bolting the planks down into the deck.
It will be hard to apply more oil where it needs it the most otherwise.

 

Just have the mill cut the 15 planks 5 1/4" wide!
And if they will only plain saw, try to get your planks from the center of the log where the grain is perpendicular to the surface.
They know what to do. They do this all day, every day...

Then you might have a little left to joint them straight after they warp while drying.
Get an extra. You are sure to have at least one unusable piece given the way you intend to dry it.

 

Look at this link.
Sawn Lumber - Quarter Sawn vs Plain Sawn vs Rift Sawn

Notice how the growth rings of the quarter sawn log are mostly perpendicular to the face of the board/plank?
This makes for a more stable and long wearing surface.

(not to mention the beautiful ray fleck you will get from a quartersawn white oak plank)

 

Your quarter sawn will shrink less. If it were me, I'd not install wet. If this is not a showpiece just use PT SYP (pressure treated southern yellow pine).

 

The modern red pressure treating chemicals eat steel, and the old green stuff is loaded with arsenic, so neither is a really good choice.
If you can get a hold of several old windows, you can build a quick and dirty solar kiln that will have them dry by the end of the summer.

 

so would it be better to leave it banded to let it dry?
i am open to suggestions here, as you all have probably figured out, i really don't know enough about wood.
and if tongue oil in sot good, what would suggest to coat it with?
on the equipment trailers, we treat the oak with used engine oil.
i would rather not do that with this truck though.
it is going to be used to move whatever.
from furniture to sand and stone. the reason for going with oak is it costs almost the same as SYP, and it will last forever
the SYP boards only last 8-10 years up here.

 

Don't use iron/steel banding.
It will leave black chemical stains that are impossible to remove due to the tannic acid in the oak .
Plastic banding is okay.

The planks should be stickered. (small pieces of wood crosswise in the stack to allow air to reach all sides of the planks)
The stickers should be aligned with each other so the weight of the wet wood won't cause the boards beneath to bow.
Maybe within a foot from each end and every couple of feet in the middle for those 1 1/2" planks 8' long.
Paint common yellow glue -like Titebond- on the ends of the rough planks to slow evaporation and hopefully prevent checking (cracks originating at the ends of the boards)
Band the stack in a few places at the stickers to restrain wood movement while it drys, if you choose.

The guys at your sawmill should know all this...

Drying Wood at Home | The Wood Database

 

This too:

http://www.irionlumber.com/uploads/W...20Aug%2008.pdf

 

yea, they band with plastic strapping. i don't remember if they put the sticks between the planks though. i doubt it because most decking wood is used rite away.

so if i was to seal the ends and build a cabinet in the back yard out of plywood say 4X4X10 with a fan on one end and a vent on the other and let it sit banded in the sun over the summer, it would help it reach the proper moisture level for this area?