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Recommended moisture content

Started by Small Slick, March 12, 2014, 10:15:28 PM

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Small Slick

My wife and I are going to build a cabin. This prompted me to "save money" by purchasing a sawmill. I am also saving money by sawing the flooring from red pine I got from my parents yard (that actually was free). So now that I am half done with about half the flooring (it's 2x6x12') I have to decide if I need to have it kiln dried and to what moist cont.

The reason I ask is because this will be a 3 season cabin subject to a lot of uncontrolled climate. It will be built in Wisconsin starting this spring.

I plan to have the boards center matched and screw through the tounge leaving no gaps between boards. I don't want gaps but I really don't want swelling that might buckle the floor. Same concept for the carsiding I am going to have on the ceiling.

Any info on what MC I need to dry to will be greatly appreciated.

John.

Small Slick

I am still searching for some advice on this situation.  I am milling some red pine to be used for flooring in the cabin I am going to build this spring. The boards are milled at 2 3/8x6 1/8x12'. Finished they will be 8/4 and center matched.

For a three season cabin up on piers, occupied only on weekends and subjected to Wisconsin weather what moisture content should I have the boards dried to?  I would like to maintain tight edges and wish to avoid gaps. I really don't want to get swelling and have the floor buckle.

John

Jim_Rogers

When people ask me this question I usually tell them to talk to a flooring installer and get the correct answer from them.

Most of the time, in the past, when I sold kiln dried flooring it was dried down to 8 to 12%.

Air drying in my area only brings it down to about 20%. Which I believe is too wet to install in a house.

You need to understand that even at 6" wide (or a little less as it will be smaller because of t&G) that these will move some from summer to winter if flat sawn. Quarter sawn will move even less. So you may have some seasonal movement. This is the nature of wood, and wood floors.

Good luck with your project.

Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

GeneWengert-WoodDoc

Certainly in the wintertime, the floor will be trying to get to around 12% MC (or higher if you do not have a plastic soil blanket or if moisture gets under the cabin).  Then, when you are in the house with maybe a little heat at times, then the floor will be closer to 9% MC or a bit lower.  So, you can make it tight in the winter but it will shrink in the warmer times.  Wood changes size with the changes in humidity.  Your erratic occupancy means variable MC and so variable size.  To avoid buckle, install at 12%.  Use a long tongue, if T&G flooring, so that gaps do not show light.  A finish on all sides will slow moisture changes.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

red oaks lumber

john
i would just kiln dry it ,that way your set. our climate up here is some of the most yoyo moisture throughout the year.
if you dont want to dry, sticker the wood in a very wide open area for max air flow, by fall it might be good enough to make floor but, you'll still have some rather large gaps by late winter. my views might be alittle prejudice towards k.d.we make alot of wood products for people with their wood, and alot of the feed back is i should of had you dry my wood :) just my .002
the experts think i do things wrong
over 18 million b.f. processed and 7341 happy customers i disagree

woodman58

As a flooring installer I install wood at 6 to 8% moisture. In your case it is going to be different. Why are you going so thick? Cutting at 1 1/4" is plenty thick. Floors of years past were laid directly over joist at 1" thick. They should be kiln dried, I would say to 6%. Then acclimate the flooring to the conditions of the cabin for 3 to 4 weeks before installing. I would definitely do tongue and grove.
i LOVE THE SMELL OF SAW DUST IN THE MORNING.
Timberking 2200

GeneWengert-WoodDoc

When installing an oak floor, we often use 7.0% MC target.  But with red pine that moves half as much as oak, we can be less restrictive.  Also, as red pine is softer, we can tolerate a bit of swelling easier without defect.  Finally, we know that pine machines much better at 10% MC -12% MC than drier.  So, this means are flooring should be around 10% in a normal application.  However, as you will not have heat 24/7, this adds to the final MC that the floor will have, so 12% is the likely maximum value.  One advantage of thicker flooring in this case is that it will dry and shrink less when the heat is on...that is, when the humidity is varying.  So, stay with the thicker floor.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

petefrom bearswamp

My house is floored with Sugar maple from 2 to 7" wide, Black cherry 3 to 9" wide and White pine, 12 to 16" wide.
The hardwood is kiln dried, the pine air dried.
All of the species shrink in the winter and expand to tighten the joints in summer, the wide board pine the most of course.
My house was built in 1994.
Kubota 8540 tractor, FEL bucket and forks, Farmi winch
Kubota 900 RTV
Polaris 570 Sportsman ATV
3 Huskies 1 gas Echo 1 cordless Echo vintage Homelite super xl12
57 acres of woodland

Small Slick

Thanks for all the info!

The reason the boards are so this is because of the floor truss design. My wife and looked at at ton of cabins in prep to build ours. We ended up with a hybrid design using an Amish technique where the floor joists are 48" on center. Our joists are made of four ply 2x8's laminated together. So the red pine flooring has to be thick to keep bounce out of that span. One cabin we looked at used 5/4 white pine and it did well.

The "logs" for the walls will also be 2x8 laminated timbers; kiln dried before lamination.

Someone mentioned finishing all sides of the flooring to slow moisture gain and loss. That sounds reasonable any product recommendations?

John

WoodenHead

Quote from: Small Slick on March 15, 2014, 10:29:33 AM
So the red pine flooring has to be thick to keep bounce out of that span. One cabin we looked at used 5/4 white pine and it did well.


The second floor of our log home has 1.5 inch (finished) T&G white pine flooring over top of 6 x 10" timbers.  Originally we had 6" wide planks.  There was far too much bounce as you say.  So we had that changed out for 10" wide planks.  That took the bounce out of things.   ;)  If it is a three season cabin, I would dry to around 10%.  If it was 4 season, I would suggest 6-8%.  Our floor was installed with wood that was a bit too moist.  It shrunk leaving some gaps.


Small Slick

Woodenhead,

What was the on center spacing of your floor joists?

John.

GeneWengert-WoodDoc

Any varnish will work to slow the change...spar varnish is really good, but urethane is fine..two or three coats
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

Bill Gaiche

Gene, how well would a deck sealer do on the bottom side of the wood or is it even practical. I thought since you could spray it on with a pump up sprayer it might work and be quick to put on. Thanks, bg

GeneWengert-WoodDoc

I would have to know what its vapor resistance is..it might be rather low.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

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