Rats under the staircase
September 13, 2021 11:53 AM   Subscribe

We have some unwelcome rodent visitors under our front staircase. Please let me know your thoughts on how to deal with this quickly!

We have cement/paver front steps that are supposed to meet a sidewalk built of pavers. Picture here. There is a "void" under the steps and there is a gap between the bottom of the steps and the sidewalk. So, for example, if there is water on the sidewalk, it tends to run into the gap under the stairs. The gap and void are "lower" than the sidewalk. I have poured gravel into the void from time to time, which lasts for a while, but eventually the gravel disappears or flattens/levels and the gap reopens. It's been this way for years and, while a little annoying, hasn't been a big problem.

Over the past few days, we have noticed a big increase in rat/rodent activity around our house - we live in the city and will occasionally see something, but more recently we have been seeing rats running around the house basically every day. Then, yesterday, we saw a rat or maybe two rats run right across the front of the house in broad daylight and dive into the void/opening in the stairs. I saw this again today, again in broad daylight, which seems really weird for rats. The rats are small, for what it is worth - like ~6 inches long not counting the tail. Maybe they are young or maybe they are mice.

So, what do I do? I vaguely think I need to get them out of there and then seal it up. To get them out of there, I am thinking of just spraying a hose into the void. I could try one of those "gas bomb" things, but I really don't want to set off poison gas near my house. Also, I think it would be better not to have the rats die under the steps and then decompose.

To fill it/seal it, I am thinking of pouring as much gravel as I can into the crack and trying to fill the void as much as possible. Then I will try try to plug the gap with a foam backer or something like that and then spread concrete around the gap. Does that make sense? Anything else?

One thing that concerns me is that I don't understand what is happening to the gravel I have poured in previously. Is it washing away? If yes, where is it going, and do I have some kind of erosion problem? Do I need some kind of more drastic mud-jacking remedy here? We do not like the front steps and we want to have them demolished/replaced in the next few years, but not right now - so maybe my gravel/concrete plan is good enough?
posted by Mid to Home & Garden (7 answers total) 2 users marked this as a favorite
I think in this case, if you have a reputable local pest control (particularly the type that identifies and mitigates entry points) you should have them come look and probably stick a scope down the void to see what's up. They can then help you form a plan of action that will probably be more permanent than any solution you guess at.

What's behind those steps? Is it foundation, crawl space, basement? Whatever the answer, you've likely got rats in/under it.
posted by Lyn Never at 12:03 PM on September 13 [3 favorites]

Response by poster: The house foundation is under/behind the steps and is ~1 foot thick concrete, so I don't think there is any way for them to get into the house. The void is near/against the outside of the foundation wall.
posted by Mid at 12:06 PM on September 13

I think you might want to hire a mason to look at this. The sunken pavers before the step are not a good sign, and a void is generally something to be avoided. I think pulling apart the stairs and rebuilding them (with the same materials) on a better built foundation is the place to go. That may involve a new slab under the stairs, or at least a better fill after whatever left the void in the first place.

It's possible rats dug the void out a bit-- moving gravel is within their skillset. I don't know where you are, but it's possible that the freeze/thaw of winter is doing gradual damage to whatever's supporting the weight of the steps, with the increasing void being a symptom.
posted by Sunburnt at 12:36 PM on September 13 [3 favorites]

I am also somewhat concerned by the settlement, but it could be reasonably innocuous if the pavers aren't very old (insufficient compaction prior to laying the pavers). If you really just want to fill the void for now, and push everything else off into the future, you could pour a sand-cement grout into the void. Mix it a bit thin, it should flow reasonably readily and will set up hard but at the same time won't require a pneumatic jackhammer to remove later on when you rebuild things.

Don't bother with fancy mixes that have polymer additives, just a basic mortar mix.

...uhh, beware the possibility that you'll trap a creature during this operation, and it may come rushing out at you.
posted by aramaic at 1:44 PM on September 13 [1 favorite]

Make up a mix of cayenne pepper, hot sauce, scotch bonnet peppers, whatever you can get that hot, with a little water. Spray it in there, being careful that a critter with tears running down its face doesn't count out. Most critters will leave and avoid fresh capsaicin. Then seal it. It's mean, but rats are a huge health problem and multiply fast. Sorry, rats.
posted by theora55 at 2:08 PM on September 13 [1 favorite]

We had a rat problem at my mothers house, rats visible during the day, disappearing into gaps under stairs leading up to the side entrance of the house etc., gaps i had regularly filled up with gravel that disappeared...

The exterminator i called said to solve the issue we needed to dismantle the concrete slabs. Once they were up, it was clearly visible that the rats had dug in the soil beneath and that the gravel disappeared into the underground network of tunnels the rats dug. He placed poison, and we poured a cement sand water mixture into the holes before proceeding.

If you cannot yet dismantle the steps, pour a sand cement water mixture into the gap, as aramaic advises.
posted by 15L06 at 2:21 PM on September 13

You can trap them ancillary to whatever you do to fill the void or repair the steps. But you have to be patient and willing to learn to think like a rat.

Once you know their runways leave out unbaited, unset traps. Then, after a few days, bait them but don't set them. If the bait is still there in 48 hours, that trap won't work; reposition it and start over.

After you have several traps that have had bait taken within 24 hours, bait them all one afternoon and with a little luck you'll have several dead rats and have done a community service.

Good luck!
posted by SaltySalticid at 4:58 PM on September 13 [1 favorite]

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