Our Cypress Bat Houses are made out of 3/4" thick Cypress except the top back which is made out of 3/4" Plywood for mounting. The outside measurements of the Bat House is 30" X 16" X 5" wide for a 3 chamber house and has 1/4"dividers with 1" spaces for the Bats. All interior surfaces are rough cut on our saw mill to help the Bat cling to the wood surfaces. All exterior cypress wood is shiplaped to help keep the inside space dry and shed any rainwater. There is a standard 1/4" ventilation slot at the bottom and all wood joints are screwed with Epoxy coasted screws for a long lasting quality built Bat House. They come in 3,4 and 5 bay chambers.. All our Bat Houses are made from American Cypress and built by Hives and More, Saints Johns, Florida.