I am in the process of remodeling a basement. I would like to add decorative trimwork including panel wainscoting. What is the best material to choose porvided the basement is prone to high humidity in the summer and dry heat in the winter? Which material tends to shrink less? What about mdf type materials?
Re: material choices
There are several choices for the wainscot. If the wall is drywall and is smooth finish, you can just use a decorative moulding in large rectangles. If the top of your wainscot is 32", you can make a rectangle 20" high and 32" long and repeat this across the wall. Put a chair rail or any other type moulding across the top, leaving a margin of 4-5 inches from the top of your rectangles. You shouldn't have much in the way of wood movement problems with this since all the wood will be in small pieces.
Another way is to use MDF beadboard, found at HD for about $8 a sheet. It goes on well with liquid nails and a few tacks to hold it til the glue sets. Trim top and bottom of it with base and moulding and you're set. Shrinkage/expansion shouldn't be an issue.
Lastly the most expensive way is to put 1/4 inch plywood along the wall, up to about 32 inches. Then take 1x4 or 1x3 and make frames all along the wall on the face of the plywood. Finish out the inside of the frames with a moulding. Hide the joints of the plywood behind a 1x upright and leave a gap of a sixteenth or an eighth between the plywood pieces. That'll handle the expansion and no one will see the crack because it's behind the one by material.