Introduction: Simple Bat House

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Bats are friendly mammals that, among others, assist in keeping keeping down mosquito populations, thus improving quality of life in gardens. They do not only eat the mosquitoes, but it appears that a bat's presence also scares the mosquitoes away. This Instructable shows how to make a small and simple single-cavity bat house. The shape of the house built in this Instructable is flat, targeting bats that prefer fissures as a dwelling. See Step 1 for the design considerations.

To make this bat house multiple sources were consulted: earlier Instructables but also other references. An overview of the sources used is presented in Step 8.

This project is fairly simple to make and might take about 4 hours to execute (less if you're an experienced woodworker, more if you opt for a finishing touch beyond perfection).

The project is very suitable to make together with children: it's not so difficult and has educational merits (both on woodworking and on nature). Supervision of an experienced person (adult) is strongly recommended.

Important note: work safely. The project can be executed with hand-working tools, power tools are not required (side-note: in the picture with the tools a drill is missing, and so are the glueing clamps).

This Instructable was submitted to the Woodworking Challenge (2017) and also to the Gardening Contest (2017) and was first published on 24 April 2017 under a Creative Commons Attribution license by Openproducts.org at Instructables.com. See Step 9 in this Instructable for some words on how the contents of this Instructable may be used for other purposes.

If you like hand-making and educational stuff then be invited to keep an eye on the Openproducts Instructables as there are some more projects in the pipeline. One of the already published educational/craft/nature Instructables is the Waterwheel from Bottles. A kids woodworking project is described in the Instructable Handworking Dice. Or, if you're more into gardening, the final step in this Instructable highlights two earlier Instructables by Openproducts.

See also Openproducts' Twitter account (see April 2017 for this Bat House project).

In the next steps the design choices for the Bat House are explained.

Step 1: Design Considerations

Based on the reference sources mentioned in Step 8 the following design considerations have been applied to make this Bat House:

  1. Firstly, the resulting bat house is not meant for bat breeding and neither for hibernating, which would require different dimensions and thermal characteristics.
  2. The basic construction element is a wide plank. In this project half a scaffolding plank was used (dimensions: L x W x H = 125 [cm] x 19.5 [cm] x 3 [cm] = 49 [in] x 7.7 [in] x 1.2 [in]). There are three main reason for opting for the scaffolding plank: a.) it is rough (not planed), b.) it is untreated (no chemicals) and c.) it is wide (19.5 [cm] / 7.7 [in]). The considerable thickness of 3 centimeter is not required, it's more a result of the selection of planks offered in the local DIY shop.
  3. The main compartment of the house is has a (internal) height of 44 [cm] (17.3 [in]), a measure adopted from existing designs (see Step 9 for references). The internal width is a result from the plank width and the thickness of the side slats.
  4. An important characteristic of the Bat House is the span of the opening. Many different designs exist and preferably the dimensions should match the preferences of the bat populations in your local environment (again, see Step 9 for more information and references). In this design it was opted to have a fissure that has a relatively wide opening at the bottom (2.5 [cm] or 1.0 [in]) and is narrowing to the top (1.5 [cm] or 0.6 [in]). One of the advantages of a widening shape is that when a bat is bearing (you never know) it will always be possible to leave the bat house (contrary to birds bats are mammals and a tight opening in combination with an increasing belly may cage them, resulting in starvation).
  5. No bottom plank was used. It would help in collecting bats' manure and to catch possible young falling out. But here it was omitted because the house is not intended for breeding, and the plank would prevent a free view from the ground into the house (for checking it's status).
  6. Based on a picture of a bat (see step 2 for reference) the lower en upper ends of the plank are decorated with bat-shaped fretwork.
  7. Fixing the backside and the front panel is done using woodworkers' glue. This ensures that no cracks are formed so chances for drought inside the bat house are minimized. Drawback is that the Bat House cannot be opened anymore after assembly.
  8. The Bat House will be hooked just under the gutter of a roof and in this way it is not exposed to rain. The roof end gives shadow in summer, which prevents overheating of the Bat House.
  9. The Bat House is not painted in order to come closer to the natural habitat of bats: caverns in a tree.

The following steps show in detail the making process of the Bat House.

Step 2: Bat Contour

Sir Andrew Smith (1797–1872), zoologist, has drawn a picture of a bat with wings spread. This picture has been used to make a template for copying the silhouette onto the wood.

The template is provided here as a raster image (PNG) and as a scalable vector graphics (SVG) image.

The next step shows how to make the ornaments.

Attachments

Step 3: Bat-Shaped Fretwork

Using a fretsaw (or jigsaw) the visible parts of the Bat House are decorated with the silhouette of a bat. The lower side of the background plank pictures the underside of the bat image, the upper side of the front plank pictures the top of the image.

Step 4: Preparing the Panels

The 44 cm (17 [in]) side slats have been shaped in the form of a wedge. At the bottom it measures 2.5 [cm] (1.0 [in]) and it is narrowing to the top to reach 1.5 [cm] (0.6 [in]).

Holes for the screws are drilled from the backside in order to keep the front panel clear.

An important step is to create grooves that allow the bats to find a place for hanging. Also, the grooves allow the bats to land on the airstrip and to crawl up into the house. The grooves should be at least 1 mm (0.04 in) deep and are positioned at a distance of maximum 12 mm (0.5 in). Here, a chisel was used to create the grooves, which worked out really fine.

The next step shows how crayons were used to add additional decoration to the Bat House.

Step 5: Drawing a Bat Picture

Using colored pencil ornament ends of the plank are finished off with a bat image. The vulnerable parts (ears and feet) of the bat image are shaped in the last stage before assembly. Note that the right wing of the upper bat does not come out well.

The next step shows the assembly of the Bat House.

Step 6: Assembly of the Bat House

Woodworker's glue is applied and screws connect both panels of the Bat House. Clamps are used to ensure the wooden parts touch firmly.

The next step shows how the Bat House hangs.

Step 7: Hanging the Bat House

The orientation of the bat house is especially important because the sum warms it up. In Northern Europe for example, a South or South-West facing wall can be chosen, giving insolation after noon. In order to prevent overheating in summer the Bat House will be fixed just under a roof (beyond reach of rain and in the shadow, which also allows not to paint it), but freely accessible for the bats.

There are bats around in the area, but expectedly it will take multiple months or even years before the house is occupied. This project was executed in April 2017; once occupants are noticed it will be announced here.

The next step introduces the information sources used for this instructable.

Step 8: References

Multiple information sources were used for this Instructable: earlier Instructables but also other references. Below a listing is given (statistics have been recorded in April 2017).

Two references in Dutch language were used:

The latter is a very extensive report, addressing an overview of bat house applications, use and success factors. The work has been assigned by the Dutch Organization for Mammals and was published in 2012. It features an appendix with many bat house types (page 107, PDF page 109).

And one reference in German language:

Das Fledermausbrett - selbst gebaut (includes design drawing) by NABU Nordrhein-Westfalen

The design introduced in Step 1 of this Instructable has important elements borrowed from two references: Landschapsbeheer Flevoland (the single-plank approach) and NABU Nordrhein-Westfalen (the narrowing sides).

The next step elaborates on the Creative Commons license under which this Instructable and the SVG bat silhouette are published.

Step 9: License

This Instructable and its SVG bat silhouette is being made available through a Creative Commons Attribution 4.0 International License. Republishing this Instructable is allowed, provided it is being attributed properly (by citing the name Openproducts as an author and linking to this Instructable and mentioning a license notice). For pictures in higher resolutions or omitting the referencing please ask by sending a Private Message through the Instructables member page (www.instructables.com/member/openproducts).

Step 10: Other Gardening Projects by Openproducts

Good to see that you scrolled all the way until this last Step 10. Two earlier Openproducts Gardening Projects are presented here as a bonus:

See also Openproducts' Twitter account (see April 2017 for this Bat House project).