Hot Topics: Rats in the Attic

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Original Post: Rats in attic

dm888 Member

For the second year in a row around this time of year, I have heard rats in the attic. Last year I set some traps up there right near the hatch and caught a few, but they seemed to go away for the summer. I understand I need to find how they are getting in, but my concern is trapping them inside if I do seal any holes. Is there some method of scaring them out first before sealing off any openings and having them trapped inside? The thought of encountering a bunch of them while crawling in the attic doesn't sound too fun, either!

Viriliter_Agite Member

I would seal the holes regardless, and then set your traps to catch any that are trapped up there. You'll never solve the problem until you can stop them from getting up there. All they need is a hole big enough to get their head thru. The body can squirm the rest of the way.

marksr Forum Topic Moderator

Rats or mice? I get mice in my attic every fall/winter. Snap traps always take care of the problem. I keep setting the traps until they are gone. Sometimes it will be just one, but other years there will be multiples of them. I'm not sure if it's feasible to find every access point, but do seal the ones you find.

dm888 Member

Well, I know they were rats last year because I caught a few in traps. I just assumed they are again rats. Will you hear mice scratching around as much as rats? I have blown insulation so when you hear them, they must be gnawing or scratching on the trusses then, right? On a separate note, I have some traps set outside and a few got tripped. One did catch a mouse in it by the rear end so I suppose it is possible there could be mice in the attic, too. A trap got tripped once, but I didn't think mice would be as noisy.

marksr Forum Topic Moderator

While I've had rats in our buildings before, I don't recall ever having one in the house. Mice can make a good bit of noise in the attic or even walls in an older house. I've laid awake at night before, swearing the little pests were eating the lumber. Rats require a larger snap trap than mice do.

aka pedro Member

I wholeheartedly agree with getting things sealed up as quickly as possible, while leaving the traps set, and checking and re-baiting them as regularly as possible. I assume that you don't know for sure where they are getting in since otherwise you'd already have it sealed, so even if you waived a wand and sent them scurrying you may or may not seal all of their entry points on the first pass. For mice, steel wool, spray foam, duct seal, and things like that generally suffice. For rats, I would go with something more substantial like solid wood, mortar, steel mesh, or whatever the breech warranted.

PAbugman Forum Topic Moderator

Can you or someone get in the attic to look for fresh fecal droppings? That should be a way to tell if it's rats or mice. Might be a good idea to inspect for damage from chewing if it's rats.

dm888 Member

Today is a nice day, so I am going to go up on the roof and try to check again. I realize they can get through the smallest of holes and can climb vertically because I actually saw one go up the wall into my garage a while ago, which I ended up sealing off. I have heard that rats can get into the walls, but even if they got into a wall from the crawl space, how can they get all the way through that joist channel to the attic? Wouldn't the header at the top stop them?

marksr Forum Topic Moderator

Often, there are holes drilled for pipes and wires in the top plate. If the hole is over-drilled, there is probably enough room for a mouse to squeeze through, but not sure about a rat.

dm888 Member

I went up there today and made my way down to where I heard them. While most of the attic has blown-in insulation, there is a portion of batt insulation down at the end where I heard them, so that makes more sense now. They were probably underneath the insulation, which is why I could hear them walking. I still don't know if it's mice or rats. I did see some rat droppings, but those could have been from before when I know there were rats because I caught some. I didn't see much else because if it is there, it will probably be in with the insulation where I couldn't see it. I put a piece of plywood up there with four snap traps screwed to it and since I don't know their path, I just put up in the middle somewhere and we'll see what happens. Do you think I should put some mouse traps up there as well in case they are mice?

Marq1 Member

You said you caught one, or some—there is no mistaking rats for mice! Either way, get the traps set and get the holes sealed!

PAbugman Forum Topic Moderator

I wouldn't use mouse traps until I was certain that the problem was mice and not rats. If rats set off the mouse trap, they won't get caught but will become trap shy and it will be infinitely harder to catch them.

My experience is that rats/squirrels will leave visible tunnels, burrows, scratchings, etc. in the insulation. If you didn't see that, then I'd consider that it's mice, which is a good thing. I'd still keep the rat traps set as opposed to mouse traps for now.

PAbugman Forum Topic Moderator

This style of rat trap with the expanded trigger can sometimes catch mice, too.

dm888 Member

I have too many different kinds of traps! I noticed some activity in the crawl space last year, too (I just have a small crawl space under a room addition) and had seen where they dug under the wall of the crawl space (there is no foundation under this room) so I started setting traps outside. They got set off a lot without catching anything, but I did catch a few rats so who knows if it was just rats tripping them or something else. I did throw a few inside the crawl space now just to make sure nothing is in there and I caught a mouse by the rear end with one of them, so maybe it was just running by. But I have snap traps in the attic now because they seem more reliable.

I have tried both peanut butter and cheese in the past (never both at the same time). Since I have several traps next to each other right now, is it a good idea or a bad idea to mix baits?

Marq1 Member

Cheese is for cartoons. Peanut butter is the go-to bait!

dm888 Member

I just wanted to report back on this. I have five traps in the attic now and have not caught anything, but I suspect they may be getting in by the chimney. I need to redo the chimney because it's a cinder block chimney, but there was some wood siding attached and it's falling apart. I have a feeling there might be a gap somewhere where it meets the roof line. Anyways, I put a trap on each side of the chimney where a rat would have to exit out of if that is where they are coming from and after being up there for two days, one of the traps was tripped. I am thinking of putting a series of traps where I put that other one. Should I put a board or something over the top of them to keep birds out? Any other ideas?

PAbugman Forum Topic Moderator

We may want to consider that this may be a bat issue. When you mentioned that wood siding is falling apart at the chimney, that is where my thoughts went. Can you find droppings, leaving them undisturbed, but take a picture for us?

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