Single Plank Bat Box

I've been meaning to make a bat box for a while, when this contest popped up I thought it would make a great project and one I could do with just hand tools.

I took the basic plans from this RSPB website, it's a fairly simple one plank build.
I'm lucky enough to live near a very good timber merchant, they carry a large array of rough-sawn wood. I bought 2 x 4000 mm lengths of 150 mm wide x 22 mm thick, the plan is to make one of these bat boxes using only hand tools for this contest then knock out 3 or 4 more using all the tools in my shop.

The only powered tool used in the making of this project was my car to get the wood.

Supplies

1 length of untreated rough-sawn wood 150 mm wide x 1100 mm long x 22 mm thick.
Hand saw
Hand drill
Screwdriver
Tape measure
Square
Sanding block
Stanley knife
6 mm wood chisel
Wood glue
20+ #8 x 50 mm screws
Wood filler
Wood primer
Finish paint

Step 1: 5 Simple Cuts

Making the pieces for the box is fairly simple if you start with a piece of the correct width.

Following the plan from the RSPB layout, the first cut is the trickiest, start by marking out both sides down the length. When making the cuts try to make sure they are as upright (90º) as possible as this will help you get better joints.

Because this is rough-sawn timber after all the parts were cut I sanded down all the edges.

Step 2: Making the Landing Strip

To make the entrance easier for the bats to enter I cut a tiny bat ladder in the backboard.

To do this I scored two lines a few mm deep across the board, I then chiselled this out.

This again was given a quick rub over with the sanding block.

Step 3: Making the Lid

The next step is to make the lid.

I clamped all the parts minus the lid together, then laid the lid won the side outside the backboard this allowed me to mark the angle I needed to plane.

Using a recently sharpened block plane I was able to put the angle on the lid making sure I stuck to the marked angle.
I left the front face of the lid without the angle because this would allow rain water to spill off the front.

Following the same method as cutting the bat ladder I added a lid width slot in the backboard, the lid can be wedged in to this slot to add to the waterproof and draft proof nature of the box.

Step 4: Hand Drill

My first issue was, I don't own a hand drill nor did any of my neighbours.

Good news... my dad had one on his boat... Bad news... It was on his boat, covered in rusty gunk and unused for years, this thing hardly turned so my first hour was spent stripping it, cleaning and giving it a grease.

I really missed my powered drill at this stage, manually drilling holes is a time-consuming task.

With all that said, I used a combo drill and countersink bit to make the 20 fixing holes through the sides and lid.
To make sure I got the fixing holes centred in the receiving piece I marked the wood width by tracing along an off cut.

Step 5: Assembly

The assembly of the box is a simple task.

The only bit that requires some precision is getting the sides in their correct position. Apply plenty of wood glue to the side of the backboard where the side will contact. Line up the top of the side with the bottom of the slot cut for the top, screw in to place. Repeat for the other side.

Apply glue to the front piece and screw it in to place between the sides.

It might be overkill but I decided to scuff up the inside back wall and inner lid, this was aid the grip for the bats.

Glue the lid stop in at the front of the box, make sure you align the top edge of the stop with the top edge of the sides.

Glue and screw the top in to place making sure you put glue the slot cut in to the back board and position the top in the slot.

Step 6: Fill and Sand

Using wood filler I filled all the screw holes and joint gaps.
Leaving it overnight to harden the following day I sanded it all flat.

Before painting it, I drilled 3 mounting holes, two in the top and one underneath in the bat ladder.

Step 7: Undercoat

Being as this is going to be mounted outside in the always beautiful British weather 😉 I decided to paint the box.

I did some research to make sure it was OK (from a bat point of view) to paint the box, most of the information i found was that so long as the inside remains unpainted it's fine to paint.

I masked off the entrance slot with some Frogtape and gave the box two coats of exterior undercoat.

Step 8: Final Coat

Once the undercoat had dried I gave the box it's final spray coat of black satin finish.

I hope this Instructable has given you some ideas and inspiration to make your own bat box. These amazing little creatures need all the help we can give them.
Don't forget the tiny Pipistrelles are the commonest British bats, weighing around 5 grams
(same as a 20p piece). A single pipistrelle can eat 3,000 tiny insects in just one night. More bats = less bugs.