Bat House Forum

[solitaryvireo]

Hi,
I'm planning to make a couple rocket boxes. I have 2 questions.
1: The plans describe making cuts into the 4x4 post. The plans don't specify how deep to make the cuts. How deep do I make them? Does it matter?

2: I read that different size spacing will attract different species of bats. The plans say to use 3/4" wood block spacers. Would using different sizes attract different species? I'm building these for western Oregon/Washington.

Thanks!

[Terry Lobdell]

Welcome! If you are referring to the cuts as being saw kerfs to roughen the surface, you can do that, but I have found that rough cut wood surfaces are all that is needed for bats to get a secure grip. If your wood surface is very smooth, then a 1/16" saw kerf will work well.

A 3/4" crevice size is about right.......both little browns and big browns will use a 3/4" crevice size. Due to slight warping that happens with most woods you may end up with the crevice spacing varying from 5/8" to 7/8". I have lots of both little and big browns in many bat boxes and the slight variation does not seem to bother them as long as the overall average is 3/4"

For spacers, half inch cpvc pipe cut to length works well to maintain the desired crevice size.

[solitaryvireo]

Thanks for the reply! The cuts I was refering to were not saw kerfs. The instructions say "cut angled notches into the post to provide more roost space" I was trying to figure out how big to make those cuts into the posts. Also I came up with a third question. The instructions (http://www.batsnorthwest.org/rocketbox_plans.pdf) say to cut the roof 5" x 7". That seems like it would be too small to overhang. Is that measurement a mistake?

[William Bagwell]

The drawing is a bit crude, and skewed at an angle to boot... Based on a standard 4X4 which really measures 3.5X3.5 the angled notches are approximately 1 inch deep at the deep end and 7 inches long. This would leave 2.5 (x3.5) inches of solid wood at the weakest point. Seems plenty strong enough to hold up a bat house to me.

[Terry Lobdell]

I don't think those notches are necessary........the larger spaces created by such notches just allows wasps to build larger nests........I have experimented a lot with different crevice sizes and from what I've seen bats get nervous about crevices larger than 7/8". I would just leave the post straight all the way to the top if I were you......

[solitaryvireo]

Thanks that's what I'll do!

[IowaNate]

I agree with Terry. The rocket house plans that you were referring to were an early attempt at this style of house which did prove successfull for bats. And leaving the post without the notches will attract less wasps.