Just to follow up on what Dave said -- his kilt was made from 13 oz cloth. Most of the box pleated kilts I make are from 16 oz cloth, which is what I prefer to work with and works out really great for an all-weather year-round kilt.

Some tartans are available in a regimental weight (18 oz) cloth -- those are:
Black Watch, Cameron of Erracht, Forbes, Gordon, Mackenzie, Stewart Hunting, and Royal Stewart.

Also, you may want to consider a heavy weight Harris Tweed cloth for a kilt. As I state on my web site, I don't have a wholesale supplier for Harris Tweed yet, but I do link to several places where you can purchase the cloth yourself on line, and then you can send it to me and I'll be happy to make the kilt from it.
http://kilts.albanach.org/tartans.html

Aye,
Matt