We have a rental in a neighborhood with a serious rat problem. Per the county, we can only hope to battle and contain the issue.

To that end, we've been paying for rat poison services for a while, but the county requires us to fill the holes, so that we can determine if the rats have been pushed back or are still active in the yard.

What is the best way to fill rat holes? I have been going back and forth between pouring dry concrete mix down the hole followed by some top soil and allowing natural water fall to fill it, or by pouring down dry cement followed by water, or by mixing cement first and pouring it down.

Clarification: I haven't done any of the above yet - when I say I've been going back and forth, I mean in my head, thinking about it.

My concern with the last bit is - if I pour wet cement down the hole, won't it keep on flowing down the hole, requiring much more cement than if I use dry mix which can pile up and block the hole, which then when it gets wet will cure in place?

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    Is it an earth yard? Won't they just dig new holes? – RedSonja Feb 26 '16 at 14:19
  • My Grandma used to stuff old nylon stockings down the holes for moles they get tangled up and die. not sure if this will work with rats but I would not want chunks of cement in the ground. Pouring dry cement in the hole will get hard over time as it draws the moisture from the ground. – Ed Beal Feb 26 '16 at 14:22
  • @RedSonja yes, if the rats are surviving, they will dig new holes. The reason the county requires you to fill in the holes is to determine if the rats are surviving or not. The idea is you poison, fill, and repeat until they stop digging out again. – The Evil Greebo Feb 26 '16 at 15:17
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    I would fill the holes.... with rat poison. – DMoore Feb 26 '16 at 17:24
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    If the point is to see if the rats are alive or not, why not just fill it with dirt? I don't understand the need for concrete. – DA01 Feb 26 '16 at 18:55

Personally I would just fill the holes with dirt, why does it need to be more complicated than that? Concrete isn't going to stop them any more than dirt, since presumably the yard is mostly dirt anyway.

  • I don't know that it needs to be. The county inspector recommended it, but I've had similar thoughts. – The Evil Greebo Feb 26 '16 at 16:24
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    @TheEvilGreebo: Unless you cap the entire yard with concrete I don't think a few concrete plugs are going to stop a determined animal that can just dig another hole. Unless the county inspector specifically requires concrete I wouldn't bother. Plus if you have to do several rounds of this, you're going to end up with concrete all over your yard. – Hank Feb 26 '16 at 16:30
  • I completely agree with Henry on the use of concrete. This seems to be something too extreme for the benefit which might not be anything at all. I can't imagine trying to do landscaping in this yard. Also what happens when rats build holes right next the concrete? It would really be hard to dig that out enough to pour concrete down. – DMoore Feb 26 '16 at 18:57

So the county is requiring you to fill the tunnel opening so that it can be determined if that opening is active or not. If that is how you will monitor the opening, through the rat moving the plugged hole, wouldn't it be better to fill the opening with a material the rodent can move? If this is the case I would plug the opening with sand. Specifically fill or washed sand used to mix with cement. It is much courser than play or beach sand and when moistened will compact tightly to a dense, but easily scratched (excavated) barrier.

Dry or wet concrete poured down the opening will only prevent the rodent from digging an opening through the ground. It may tunnel around the impervious concrete, but it may be at a new and remote location leading to the false conclusion that a different rat has appeared in a new tunnel. Make it easy for the vermin to dig through the same tunnel.

But, after reading additional comments a more direct answer to your question would be to pour as much pre-mixed DRY concrete into the opening until it fills to the top. Then with a rod tamp it further down the hole and pour in more dry mix. Repeat again. If you feel the mix needs to be impervious to not allow the vermin to escape add water in short increments allowing each to be absorbed into the dry mix.

BTW: rodenticide is a dangerous and powerful poison. Food scents are added to them that are not only attractive to the target pest, but to domestic pets. Also if a targeted pest has ingested the poison and is consumed by a non-targeted animal the poison can affect that animal in the same way. Good luck and Happy hunting.

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    Nobody wants to leave any clue as to what they feel is not to their liking with any part of my answer? I'd like to know so that it can be corrected. Were all in this together people. No need for spiteful revenge down votes, right Iggy? – ojait Feb 27 '16 at 0:57

I am active in my block association in NYC - where we have plenty of rats to battle on an ongoing basis. Here, both the private exterminators and the city exterminators bait the holes in the ground (we're not talking about inside buildings here - but outside - in tree beds and gardens and parks) to try to reduce and ultimately eliminate the rats in a burrow. Then the holes are filled in with dirt. This way everyone knows if the poison is taking effect or whether the burrow is still active. I simply can't believe your public officials would want you to fill in rat holes in an outdoor space with concrete. It pointlessly eliminates drainage. If you have rats in buildings and you can identify entry points, then yes these entries should be sealed with metal or concrete. Hope this helps


Just use concrete with lot of jelly stones and most important , use glass pieces when u fill . I don't understand why people make things so complicated . When you have the oldest and most effective ways

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    Concrete down the hole is effective? At what, making the rats dig new holes? – The Evil Greebo Aug 2 '17 at 12:13

From the centre for disease control: "Fill small holes with steel wool. Put caulk around the steel wool to keep it in place. Use lath screen or lath metal, cement, hardware cloth, or metal sheeting to fix large holes. These materials can be found at your local hardware store. Fix gaps in trailer skirtings and use flashing around the base of the house. If you do not remember to seal up entry holes in your home, rodents will continue to get inside. Outbuildings and garages should also be sealed to prevent the entrance of rodents."

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    Can you provide a link to the source? Paraphrasing / quoting the relevant parts is excellent, but including the source is vital, too. – mmathis Sep 19 '17 at 17:56

The County's right & I think you're more right in planning a dry cement topped off with a little water to get the hardening started before capping with dirt.

However, I'd suggest pouring a box of D-con (for example), even mix it up with some peanut butter or something that makes it attractive & won't go rancid or lose it's appeal, down the holes first either before the cement or instead of it.

If the Rats are still around they'll use the holes as long as they're there. But, with the rat poison deposit in each hole you're more likely to collapse or eliminate the population that still might exist, at least around you.

  • The input is appreciated but the question is about how is the best way to add the concrete, not how do I poison the rats. – The Evil Greebo Feb 26 '16 at 15:19
  • Really, are you sure I didn't answer appropriately? If they dug holes in the first place then they'll simply dig around any spit wad or simply drill a new outlet if the spit wad big enough & leads them to the surface. You need to address them, not just their holes for keeping the County happy. You need an attractant & lingerer for any poisoning to work, your money sucking "exterminator" should know that, then there's no reason for anything else but simple dirt to fill the holes. – Iggy Feb 26 '16 at 15:44
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    Yes, I am absolutely sure that you did not answer the question of the best method for filling in the rat holes. The fact that the rats will dig out if they are still alive is irrelevant to the question. I stated in the question that we have been having a containment treatment done for some time, but the county requires that we fill the holes to determine if they're still active or not. You may think that's trivial, but the threat of a multi-thousand dollar fine from the county if we don't trumps your opinion. Sorry. – The Evil Greebo Feb 26 '16 at 15:48
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    Exactly! Is dirt not good enough for the ground? Is 1-step overly complicated? Would the County not pass dirt as the filler? I'm not trying to fight with you I simply agreed with your plan & then, I thought, gave you an infinitely better recurrence threat solution. I realize you're "evil" & might be looking for a fight, but you should be filling the holes with dirt by now. I simply suggested a precautionary alternative that you had not considered & somehow I'm being brutalized for my poor wording. – Iggy Feb 26 '16 at 16:15
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    Spreading peanut butter flavored d-con around a yard is a terrible idea for all the local animals...both wild and domestic. It's also not easily monitored (which is important when trying to figure out if one still has a rodent problem) – DA01 Feb 26 '16 at 18:57

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