Thursday, July 1, 2010

What is the Scratching I Hear in My Roof?

I get questioned occasionally about how to tell what it is that is making a scratching noise in a roof. "Is it rats, mice or birds........or elephants?"

If you are hearing scratching or gnawing sounds in your roof void it is unlikely to be elephants (well, not fully grown ones) but what ever it is can sound 'pretty big.' Ceilings amplify sound like the sounding boards of musical instruments. And if the noises are heard at night when there is little other sound our ears are more sensitive and amplify the noise in our minds.

A good guide to deciding whether the noise is caused by birds or rodents is the timing of the noises. If you are hearing the noise predominantly in the middle of the night, you almost certainly are sharing your home with rats or mice. If the noises are only occurring during the day or at dusk and dawn check around the eaves for birds entering and leaving.

OK. So you are hearing the noises in the middle of the night. Is it rats or mice? Rats are larger and do make louder noise but that is little help if you have nothing to compare with. Listen instead for the frequency of the scurrying feet. Mice make a sound where their paw sounds follow each other so quickly it is very difficult to separate them, so the sound is almost continuous. The sound of rats running displays a more definite sound of their individual paws.

Rats and mice have incisor teeth (front two teeth of each jaw) that are large and continually growing. The teeth have hard enamel on the front surface and softer dentine behind. As rats and mice gnaw they wear the teeth down and sharpen them into chisel like implements through uneven wearing. Rats and mice gnaw things other than food to keep their teeth worn down and sharp. Unfortunately for us they often choose to gnaw wiring, plumbing, joists and items stored where they are.

If rats and mice regularly use a hole or gap to pass through they will gnaw around the gap to open it up and make it easier to enter or exit. They will gnaw wood, plastic, metal and even concrete if they need to. The sound of rats or mice gnawing can can be distinguished by the rate of biting. Mice gnaw at about 4-5 per second, rats 1-3 per second.

A simpler way of determining which rodents you have in your roof is to enter the void (if possible) and look for evidence in the form of droppings. Mice produce small black-grey droppings approximately the size of a large grain of rice. Rat droppings are much larger, 1-2cm long.

Why did the rats move into the roof?
Because they heard the people say the cheese was high.

30 comments:

  1. Thank you! Very helpful and glad I stumbled into this! :)

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  2. This post has good and valuable information; it’s nice to see some good articles like this one.
    Thanks for creating this great informational resource.

    roofer

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  4. I hear sounds like someone is running on my roof after dark usually at midnight. It's quite scary :(

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  5. Where can the rats live in my house? I can hear the gnawing noise and scuffing steps in the early morning (between 5am~6am) on the first floor bedroom (our house is a 2-story house). My husband and I went to the attic and found no sign of rat / mice droppings ... Confused.
    What professional help can I get?
    Thanks!

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    Replies
    1. Hi Jane,

      Thank you for your question.

      The droppings of rodents are often left under insulation and in the walls etc. So you may not find them easily. But what you describe suggest there are rodents in the roof.

      Delete
  6. Hi

    The borer holes in our weatherboards are too small to get the injector nozzle into. Can you buy really tiny nozzles, or is there another way we could treat these?

    Patrick

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  7. Hello Patrick,

    Thank you for your comment. The NO Borer Aerosol Injector (which I assume you are referring to) has a nozzle which one end fits into the can spray head, the other end is tapered and has a flange to prevent product blow back. The tapered end should push into the flight holes of common and native borer beetle. It may appear too large but you will find the flight holes are larger just inside the surface. Push the nozzle in and the hole will open up. This means a good seal is created when injecting and one is more able to see which holes have been injected.

    if the holes are still too small, I wonder whether the holes have been created by something else.

    Get back to me and I may be able to advise further.

    David

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    Replies
    1. Hi David - thanks for your reply. It is the injector that comes with the "BV2 Borer Injector Spray" that I have. I managed to get it into some larger holes but 80% of holes are too small. Maybe I will look for the No Borer Aerosol injector to see if it is smaller. It is definitely borer holes.

      Patrick

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    2. Hi David - thanks for your reply. It is the aerosol injector that comes with the BV2 Borer Injector Spray. I managed to get it into some of the larger holes but most are too small. Will look out for the other product to see if the injector is smaller.
      Patrick

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  8. Hi David, Will a borer fumigator in a roof space make rodents leave or are they unaffected by it? If they do leave I imagine they'll come back when the smell goes.

    Trevor

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  9. Hello Trevor,

    Despite suggestions to the contrary, Borafume fumigators or any other fumigators are unlikely to make rodent leave an area permanently.

    It is much more important to both prevent rodent access and to control those that are already using the roof space using rodenticides such as Kiwicare NO products.

    Check out http://www.kiwicare.co.nz/pest/products/

    David

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  10. We can hear this constant scratching noise in our wall. We have a brick house and this is on the second floor It's noisy, constant and when we bang the wall nothing scurries it just keeps going. It sounds like a scratching. Thoughts?! It's freaking me out!

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  11. Hello Nb,

    Where in the world are you? Is the noise there day and night? If there are timbers in the wall there are insects that can make a constant noise that is often mistaken for scratching. Other possible explanations include a tree or other object scrapping the outside, is the noise still there on very still days?

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  12. Hi I hear scratching mornings between 7-9 never ever at night but it also sounds like something running across the roof. Is this likely birds? Thanks jaime

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    Replies
    1. Hello Jamie,

      What you describe is almost certainly birds waking up and becoming active in the morning. There may be a nest in the roof.

      Delete
  13. Thanks, David, for your great post. Would you please also let us know the solutions to the problem (mice or rats in the roof)?

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  14. Hi, I would refer you to this page on the Kiwicare website http://www.kiwicare.co.nz/pest/pest-advice/animal-pests/

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  15. I hear 3 or 4 loud clicks come from my wall in rapid succession then a break of a few seconds and similar noise at night. Any ideas what this could be

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    Replies
    1. Hello,

      Thank you for your question. What part of the world are you in? There are many animals and insects that could be the cause. It could also be creaking due to heat expansion or contraction of materials in the wall.

      Delete
  16. Hi David,

    Hearing sounds of scratching in the rafters of a vaulted ceiling. Starts around 10pm. Nothing in the attic though. When we bang on the ceiling, it stops for a few seconds and continues, but stays in place, does not move at all. It doesn't matter how loud we bang, it keeps on making noise. Thanks. Jeff

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    Replies
    1. Hi,

      What you describe does not suggest rodents. It may be noises caused by contacting timers as they cool down at night or it could even be wood boring insects such as death watch beetle.

      Delete
  17. Hi David,

    I was woken at 1:30am this morning to a loud scratching sound in what appeared to be the loft and then moved to the wall above the window. We have had squirrels before but repaired all facia boards and I cannot see where anything would now be able to get in. Do you think it may be squirrels again or some other type of rodent? What should my next course of action be?

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    Replies
    1. Hello,

      If you had squirrels in your loft before, they are the most likely culprit. But also look for signs of rats and mice. Rats and mice can get in through smaller gaps than squirrels. A mouse can get through a gap as narrow as a pencil.

      If you can get into the loft take a look for droppings which would help you identify the noise maker/s.

      Delete
  18. Dear David
    I live in Australia in a semi-rural location. I live in a big house with a flat roof. The last few months I have been awaken at 5 or 6am by loud gnawing for about 15 minutes and then it stops. There is no other noise. It is hard for a human to get into the very limited roof. A relative unscrewed part of the roof and put some rat bait there. He saw a few rat droppings. It appears the animal has not taken the bait. It appears to .be a solitary animal. What to do? I believe a rat can get into a ceiling through a tiny gap....Vicki

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  19. Hello,

    Give it a few days for the rat to take the bait. Rodents are neophobic and may ignore the bait for a few days then it will take a further few days for the bait to take effect. You could also put some bait in bait stations outside and around the house. The rat/s is likely to be moving in and out.

    As you are hearing the noises not long before dawn I would also check that the noise is not caused by birds.

    David

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  20. I live in New Zealand and I have a noise in my roof consisting of scurrying noises and rustling about only at night time this happens and its rather loud. I have had this noise in my roof for awhile now at least 4 months. Its starting to concern me

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    Replies
    1. Hello Virginia,

      What you describe is typical of rodent activity. It is autumn in NZ and this is a mast year where more than normal seeds have been produced by trees. This has provided plenty of food for rats and mice in the wild and there is likely to be a great influx of rodents seeking food and shelter in homes and other buildings.

      Now is a good time to be pro-active and check for and seal possible entry points and place baits and traps in roof voids and other vulnerable parts of buildings.

      Delete
  21. Hi there,
    I live in Sydney Australia single story house steel frames no insulation at all between walls or roof cavity we, we have been hearing scratching in our wall behind our bedhead but we never hear it in other parts of our house we usually hear this at 10pm or 2am etc have not notice the scratching in the day, but then we have noise sometimes that sounds like something is rolling a rock through our roof sometimes it sounds like banging it's always so loud but I'd say that's because of the steel.frames these sounds can be about 6am again late at night, we also have a solid concrete raised foundation all, no trees or overhanging branches our bedroom wall shares its wall with our garage my husband did put baits up there along with traps, it would eat the cheese the trap didnt go off whatever it was stopped or didn't visit for about 4 weeks but is now back :/ our roof is hard to manoeuvre due to the location of the noise does any of this suggest anything?

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    Replies
    1. Hello,

      Thank you for your enquiry.

      Your description does suggest rodents as the most likely cause. I suggest putting fresh rodenticide baits in the roof and traps. I don't recommend cheese as a bait for traps as it is fat that has 'gone off'. Chocolate or peanut butter are better baits. And be sure to fix rodenticide baits in place. Some rodents will take baits away to store (cache) them and it might be this that sounds like 'rolling a rock'.

      Delete

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