Excluding bats from your roof

Not everybody thinks that bats are cool, or cute. Although bats can and will mostly live in the roof of a house without being a nuisance to the occupants, some bats do carry a strong scent, and if the guano starts piling up things can become problematic.
If you really have to exclude bats from your roof, here are a few handy tips.
Letís start with when NOT to exclude bats. Bats in South Africa do not go into full hibernation, but they do go into torpor and become much less active in winter. If you exclude the bats in winter, they could find it hard to find a new place to stay, and could die of cold. Also, because they are less active in winter, you might actually be sealing them in, which means they will die in your roof, leaving you with a potential mess.
Donít exclude during the maternity period either, which can range from middle September to about February (in South Africa).
Remember, the babies cannot fly, and if you stop their mothers feeding them they will die, again leaving you with a mess. The best time would be at the end of summer. Baby bats reach adulthood by end of the summer, and can fly and find food and shelter for themselves.
To exclude bats, you need to seal all the holes where they can get in and out, except the main access point. You then fit a one-way bat valve over this opening, so the bats can exit but not re-enter. Then, after a few days, you remove this valve and seal up that hole too.
Firstly, find that main access point, or points.
Check around your house for bat droppings. OK, if you reading this article, you probably know exactly where they are going in and out by now. Check for stain marks under the eaves. The bats leave a coating of oil from their hair when they go in and out. You will usually find these stains where the walls and the roof join up, under loose facia boards, broken vents or any other crack or opening. Some species of bat are really small, and can crawl through an opening the size of your pinky finger.
If you know you have bats and still cannot find the entry points, what you need is a beer. And a chair. Spend time at dusk, sitting in a comfy chair and watching your house carefully to see where the bats are exiting. These holes will usually be quite close to where the bats roost inside the roof or opening. If you are working alone you might have to use several evenings, as the bats generally start exiting around 30 minutes before dusk. If you have family members to help you, consign a part of the house to each of them to broaden your area of inspection.
Watch carefully how many exit points there are, and how many bats there are.
Step two is to fit a one-way bat valve over the entry/exit points.
One way valve made from netting or sheeting.
Secure plastic, lightweight, flexible netting with a 0.4 mm mesh or smaller to the building along the top and sides of the opening. The idea is that the bats should be allowed to exit, but not return.

Make sure that the bottom is loose, so that the bats can crawl out, but not so loose that they can crawl back in.

You can also use plastic sheeting like you have under the roof tiles, or even paint drop-sheets.
Now, check again when the bats are exiting. Make sure your bats are in fact exiting, and are not trapped inside by your valve. Make adjustments as needed until you are sure your bats have exited the premises. Again, try to count them to make sure they are all out.
One-Way valve using PVC pipes.
On some buildings, like those with brick or stone exteriors, log cabins or any other building with a rough exterior wall, you might have to use this method.
The tube should be about 50 mm in diameter and 25 cm long. Use PVC or flexible tubing. Bats cannot cling to the insides of these tubes, so they will be able to slide out, but not get back.

Right, valves up?
Now, go and seal all holes big enough to stick your pinky into. A warning here, sticking your pinky into holes might cause spiders and other nasties to sink their fangs into you. You have been warned. Expandable foam is usually a good option to seal these holes with.
After that, wait for a few days for the bats to exit. This might entail having more beer in your comfy chair, watching the house. Like humans, bats do not go out every night, and it might take a few nights to make sure that the whole roost has left.
Once you are sure that the bats have left, remove the one-way valves and seal up the main entry/exit points.
If one of your neighbours suddenly starts complaining about a bat problem, keep quiet. Those are, or rather were, your bats, and you donít want to give your game away. Tell them that bats are really good, they eat mosquitoes, beetles and every other kind of pest, and that in China, bats are considered symbols of good luck. (No really, they are! Google said so.)
In truth, it is not that easy to get rid of bats. They can crawl through very narrow gaps, and will probably find a way back into your house.
If you want to help the bats, you should consider putting up a bat-house. This will give the bats somewhere outside to live, and will give the homeowner the benefits of having bats to keep the pest population down.
Remember, bats are part of a healthy ecology, and a healthy ecology means a healthy family!
For more information on bats and bat exclusion, see the GNORBIG website (Site also has pictures of one-way bat-valves).

You can also contact Sharron Reynolds for assistance. Sharron is an active member of GnorBIG, has been involved with bat rehabilitation work for over 5 years and will gladly assist.


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