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Community and Q&A

Can bees damage a structure if they get behind the siding?

mikkelsen | Posted in General Questions on

If bees/wasps/ect get behind the siding of the house such as in a rain screen detail, can they cause structural damage?
If just a straight fiberglass insect screen is installed against the wall sheathing and folded up over the furing strips, is this sufficient or should it be wrapped over something solid like the cor a vent product? I know it used to be detailed this way before products like cor a vent, but were there legitimate issues with bees/wasps?

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  1. GBA Editor
    Martin Holladay | | #1

    Unlike termites, bees and wasps do not cause structural damage, to the best of my knowledge.

    Many homes have rainscreens detailed as you propose (with insect screen). If the insect screen is of decent quality, and if the installation work is careful, this approach works -- as long as the insect screen isn't damaged by a weed-whacker.

    Insect problems are local issues. A type of insect that causes problems or irritation in one state may be rare or absent in a nearby state.

  2. JC72 | | #2

    Eastern Carpenter Bee is a possible candidate if one doesn't have an adequate insect screen.

  3. Dana1 | | #3

    Before dense packing the walls of my 1920s antique I had a wasp nest in a stud cavity below a window. The entry/exit point was a 3/8" hole that the wasps had chewed through 9" clapboard & 1x plank sheathing. But it isn't a structural problem any worse than what the cable-guy does on a daily basis.

    There is also a section of roof that had carpenter bees 10 years ago that I'll be inspecting closely when I re-roof. The roof deck doesn't seem softer there, but they definitely bored through the ends of the plank sheathing in several locations ( which I filled with wood putty and repainted after evicting them.)

  4. GBA Editor
    Martin Holladay | | #4

    I don't know much about eastern carpenter bees, so I looked them up.

    "A female eastern carpenter bee excavates a half-inch wide hole in wood. She prefers to use/extend the nest she hatched out in, so over the generations, the bees may leave wood decidedly honey-combed. One source says that she vibrates her body while rasping with her mandibles. When she’s about an inch into the wood, she makes a right turn and excavates with the grain for maybe six inches more, creating a gallery. It’s hard work - it takes almost a week to dig out an inch. A single entrance leads to individual chambers, from six to twenty or so of them."

    According to another source, "Females use their strong jaws to cut into wood, making holes as large as their bodies. ... They rarely bore enough holes to weaken the structure they're digging into."

  5. Expert Member

    The problem with letting bees or wasp colonies nest in your walls isn't that they damage the structural elements directly, it's that they fill up areas you have intentionally left void (like rain screen gaps) or displace insulation materials and block ventilation paths.

    Perforated flashing provides a much better and more resilient way to block their access.

  6. Andrew_C | | #6

    Perhaps not structural damage, but I’ve seen bees/paper wasps chew through drywall in the Midwest.
    In southern states, many of the bees have been Africanized – you do not want to provide any place that harbors these bees, they are nasty and potentially deadly, even for healthy adults. Furthermore, if a swarm decides to take up residence and they have time to build up honey in their hive, you’ll have to tear out the walls and get rid of the honey and remnants of the hive after you have a professional exterminator kill the colony of bees. The bees help air-cool the hive by beating their wings. When you kill the bee colony, the hive warms, the beeswax melts, and now you have honey running into everything. And it will attract other pests.
    I was talking with an old-timer Tucson native that began working on pest control before the Africanized bees arrived, and has seen the evolution over the decades. He had a lot of horror stories. Bottom line, you don’t want bees or wasps in your house. Do what you can to prevent it.

  7. drewintoledo | | #7

    I agree with Malcom here. I raise honey bees. If you do get a honey bee infestation, not only will they fill up areas that are intentionally left void, but they will most likely propolize any cracks or holes around the nest, including the mesh on the screen. Propolis is essentially tree sap harvested by the honey bee.. Just getting the lid that sits on top off of my hives is a chore after they've welded it shut with propolis. If you have bees and manage to scrape out the nest you won't get it all out. If the screen mesh becomes propolized, it will most likely need replaced. I guess that's not considered structural damage however. I can't comment on other types of bees.

  8. Expert Member

    Andrew and Drew,
    I got a call-back by the owners of a small office I built who suspected a plumbing leak. It turned out to be honey from a nest in the floor system. Boy they make a lot!

  9. mikkelsen | | #9

    Do rain screen siding details put a wall at more risk for these issues? Is it worth the risk? High elevation central Idaho, 28" precipitation a year...mostly in form of snow.

  10. drewintoledo | | #10

    For some reason, I missed Andrew's post and I agree 100%. It will get messy.
    Malcom, If the perceived plumbing issue is a current issue and the hive can be easily accessed you can probably find free removal by posting an ad on craigslist. I'd remove honey bees for free if the job wasn't too difficult.
    Eric, A properly designed rainscreen wouldn't attract bees unless there are perforations for the bees to enter/exit. They'd have no desire.

  11. GBA Editor
    Martin Holladay | | #11

    The benefits of a rainscreen gap far exceed any insect risks.

    Do a careful job of installing your insect screen or perforated metal flashing, and you should be fine.

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