Basswood is commonly considered the best wood to make shutters from. It is a hardwood (comes from the linden tree) although it is relatively soft. It is also lightweight and stains or paints well.
A second choice is to use poplar. It is harder and heavier, and can sometimes have a greenish cast to it which may be an issue if staining. Poplar is more readily available though (it can be found at Lowes or Home Depot).
Finally some people will make shutters out of oak or even maple. These will result in shutters that are much heavier and more expensive, although they will wear better and possibly match other trim in your house that is oak or maple.
I buy the wood for the stiles and rails from a local hardwood supplier (MacBeath Hardwood). They have a large variety of different hardwoods for a good price, however the lumber is somewhat different than your standard Lowes or Home Depot boards. It is mostly rough sawn, with 2 sides surfaced. This means that two sides will be pretty rough wood (sometimes even bark) and the other two will be smoother, although still need sanding or to be planed. The thickness of the wood is stated in quarters of an inch… so 4/4 is said “four quarters” and refers to boards an inch thick. 6/4 and 8/4 are other common sizes.
Make sure to measure the wood and don’t assume 4/4 is truly an inch. The wood will shrink as it dries, which can sometimes cause one inch to become ¾. In this case the “actual width” would be ¾” while the “nominal width” is 1”. On that note, make sure the wood you buy has already been dried (preferably kiln dried) or you will have problems.
The quantity of wood you are buying is measured in board feet. 1 board foot = 144 cubic inches. To calculate multiply the width of the board by the length of the board by the thickness of the board (all in inches). Then divide by 144. For example: a board 5 inches wide 30 inches long and 2 inches thick will be (5 X 30 X 2) / 144 = 2.08 board feet. I pay about $2.90 per bd ft for Basswood at Macbeath.
Going into a store like this is slightly intimidating for the first time… the employees point you to a bin with randomly sized boards in it. You can choose whichever boards you want and they will cut off portions as long as there is 6 feet left to put back in the bin. I always fumble around for awhile trying to find one that is close to the size I want without too much extra, but I get there eventually.
This is a picture of a 6/4 board and two 4/4 boards I bought from MacBeath:
I buy the wood for the louvers from a place called National Balsa. They sell “sheets” of basswood which greatly reduce the labor needed to produce the louvers. I will give the details of the louvers in a later post, but I prefer to buy 3/8” thick pieces that are 3” wide and 36” long, although the length will vary for your window. The cost is slightly higher than buying rough lumber, but it makes a higher quality louver with less work. Tilt rods can be made from their “sticks” also.
These are a couple pictures of a shipment of I just received from them: