Humidity and Wood Interiors

[Melbo]

I live in the desert. I have installed wood panels inside the bus. When I drive to more humid climates I have "issues" with the wood. We have been in the bus for about 10 weeks now and I am noticing that in certain areas wood is not laying like it used to. I'm sure it is an issue with the humidity. It only seems to bother the larger or longer pieces. They bubble or don't lay as flat as they did when installed. I am going to take them out and cut them down and install them again. What is the optimal size for wood to avoid problems from warping when changing from dry to humid climates.

Looking for ideas and opinions here.

Thanks

Melbo

[viento1]

What kind of wood is it? Oak? There are scarfing techniques to stabilize things. Sounds like a floor, do you have room for expansion? is the wood curling or heaving?

[Melbo]

some is pine lattice some is oak plywood some is utility plywood --- just general wood no flooring involved. I bought the bus and it had "junk" pergo "junk" flooring that I have not addressed yet.

I used 4 by 8 sheets to cover interior walls and 8 foot strips to cover seams

The wood doesn't seem happy the way I installed it and I was looking for alternatives.

Melbo

[Runcutter]

Melbo, Rule Number One is that wood moves.  For all other Rules, refer to Rule Number One. 

So, it's a design issue to cope with movement of solid wood.  That's the reason you see frame and panel doors, the larger panel floats in mortises (grooves) in the solid frame, free to expand and contract.  Seasonal movement is across the grain (width) of the wood, it doesn't get longer or shorter lengthwise.  Other movement related to unseasoned wood includes "cupping", as solid wood tree rings try to flatten out; twisting, crooking, etc.

What it sounds like here is that you're dealing with seasonal (humidity-related) movement across the width, and perhaps cupping as the edges of the board move.  There are some wood movement calculators available on the net.  As you work on the coach, think of one of the rules I've learned.  Inside of tree is outside of project.  Thus, as the wood cups, the joints (edges) move toward the backing.  Also, always leave room for widthwise-movement, such as frame and panel construction.

If I'm reading your initial post right, it's also talking about plywood moving.  That one has me kind of baffled so far, the criss-cross lay of plywood (or other engineered wood) is intended to counteract movement, layer by layer.  Perhaps with more information, (pictures?), some of us woodworkers here may have some additional ideas for you.

Arthur

[gcyeaw]

  One issue with wood is if you put a finish on one side only. Moisture  is absorbed from the unfinished side much quicker and causes the wood to warp. Finishing both sides can reduce, but not eliminate, this problem as the moisture will be absorbed more evenly, and more slowly depending on the finish.

[Runcutter]

Great point.  A lot of quick sayings come to mind as I'm working on projects.  Outside of tree, inside of project. 

What you do to one side of the wood, you do to the other -- Gcyeaw's point.  That goes for both finishing, and veneering -- veneer both sides of the wood.  The non-show side doesn't have to be expensive veneer, but the point is to keep moisture absorbtion equal.

In hand-cutting dovetails, I don't know how many times the phrase "the tail is Busting Out" has kept me from marking tails backward.

Arthur

[bobofthenorth]

Isn't that some kind of an engineered wood panel you were using Mel?  If so I think that stuff is notorious for swelling.  With all our humidity problems over the years the solid oak and oak plywood absolutely has never been a problem for us.

[eagle19952]

FWIW, I have oak ply only and no problems in a 1997-8 conversion,
with "fabric" and formica living surfaces..

[Marcus]

I live in Florida where humidity is usually high. When bus is not occupied I leave the air on at about 86 degrees to help keep the moisture out. I have cherry wood through out including doors with no issues at all. You can't leave wood unfinished in an uncontroled envirement with out problems. Wood is what it is. But it's not hard to keep it nice with a little planning. Thanks, Marc

[skihor]

When laying sheeting in a house, (roofs or floors), it is advised to space 1/8" between all edges to allow for the expansion. Flooring needs a minimum of 1/4" from walls. A good Polyurethane construction adhesive can help on sheet goods, and as mentioned, sealing ALL sides/edges can also help. Letting your materials "acclimate" before installation along with installation temperatures not being extreme helps.
It's hard to deal with the expansion/contraction rates of dissimilar materials at best. Tyvek might also help for the walls.

Don & Sheila

[TomC]

When I first started my bus conversion, I had the bathroom door on with Kemlite on the inside, but the outside was not finished yet.  Went to the bus conversion convention in Laughlin, Nv and with the warm dry climate the door warped.  When I got back to my normal climate, the door straightened out and then I finished the door with clear urethane.  Haven't had it happen again.  As mentioned before make sure all sides of the wood is sealed and then the humidity/heat factor won't be as noticable.  Good luck, TomC

[qayqayt]

Very interesting discussion string.  The previous owners of our coach were snowbirds and the bus spent all it's winters in Arizona.  Since we purchased it three years ago we have it stored through the winter here in Vancouver BC.  Our winter climate is rainy and damp.  The first year the condensation was literally washing down the interior walls.  We put in six containers of DrizAir dessicant crystals and cracked some windows for fresh air and it helped alot (we don't have access to electricity so a dehumidifier wasn't an option) We've had panelling delaminate and every year the bathroom door which is solid wood, expands and we can't close it until early June.  Next year when it dries up, I'll try varathane on the door to see if it works.

Thanks for the ideas...

Bryan

[Melbo]

Here are a couple of pictures of the swelling / warping that I have experienced. I think that finishing the wood would make a big difference so I will make it a point to do that before I install it so it can be finished on all sides. I still think that long / big pieces of wood or plywood or even masonite will be more problematic than smaller pieces.  Thanks for all the information and help on this.

Melbo

[Mex-Busnut]

I am planning on painting all of the backsides of my ceiling panels before I install them, to help make them last longer.