I have a job that the client thought was squirrels but turns out it's mice. It is a long ways from the shop and I was wondering what sort of one way door or valve might be effective for them. It's a typical dormer entry where the soffit meets the roofline. Its just too far away to snap trap efficiently. All thoughts on this are appreciated.

JMO that would be Ineffective and a waste of time without a 100% seal up and even then without seeing mice being removed you really wouldn't know if the method is working and run the risk of them finding another way in and out if you're not there to maintain it. Also depends on how well the dormer was constructed. I've had dormers where you could slide the soffit and j channel with your hands and in return they took advantage of the give and made their way back indoors. I'm also not a fan of rodenticide but If you can legally handle it I would at least try that if you can't make it there to maintain the job. I'm not one to turn down rodent jobs but it wouldn't be fair to the customer. jmo

I have used and make excluder one way systems for mice, shrews and voles for a long time. They work great but you do need to do some preventative seal work as stated as is reasonable.

I first stated using them for ground level mice, voles and shrews in ground level screen vents that are used in some block construction for crawl spaces to breathe. These vents are always very low to grade so they are prone to rusting and then chewing is eminent in time.

I have seen voles, mice and shrews fire right through these devices. I have had several exit right between my knees in front of me when kneeing to finish a device install on many occasions. They do work.

If you block off the vent screen with plywood or heavy cardboard and insert the device in over the chew holes they find them fast and will use them. Give them the air flow and the small light source illuminating the vent area and they find it very quickly.

I leave them on for a couple of weeks or longer. It really depends on the time of year.

Summer months with warmer temps get the best activity obviously. Not sure how well they would be in winter and cold temps as most rodents won't stray far from their comfort zone usually once they become familiar with their new habitat. But may depending upon food needs at the time.

In that case I might leave them installed all winter until late spring to remove them.

Here are a few photos of the devices and mounting plates to fit various positions on an average venting screen that are common in our area.I have placed a 1-1/4" washer by the devices as a reference to size this is always helpful. The opening is 1-1/2" made with 1/2" x 1/2" 16 Ga.GAW wire. The excluder is 6" long. They can be made to fit any situation that will suit your needs.

The door is a very light weight 1/4" hardware cloth material. Built much like other larger excluders used for squirrels etc.

If you Google Reapeating mouse trap several options should pop up

Thanks for the input guys. This house is very tight, save this one dormer (which I will properly seal once everything is quiet). Bob, that is exactly what I was thinking, just wasn't sure if they we would push the door open. I will also look into commercial repeaters.

No I don't sell the devices I made them for our own use and have used them for many years. They are not difficult to construct. Get the wire, hog rings and some benders and you can put some together very quickly.

I don't have much experience with mice. I was referred this job by a bug Guy who thought it was squirrels. I have been doing more and more mouse work the last few years, but it was all local and snap trapping was feasible and worked well. I am going to install a one-way door this week and see how it goes.

Something to keep in mind...... mice are not like raccoons or bats which just sleep in the homes. 95% of mice that enter homes never leave again. They have a food and water source inside, so the one-way eviction doors may not provide the result you are after. Such methods may work for mice that are nesting on the top of foundation walls and feeding outside on grains, seeds, etc, but for the clients that have mouse sign in their pantry or food storage drawers, you'll need to use traps inside. They aren't going to carry their Cheerios outside to eat.

Thanks Ron, I wasn't going to say anything because I thought perhaps different mice in different parts of the country. Trying to evict mice here would be like using "Do Not Enter" signs!

Good point, Ron. I just had one like this where I had to open up the ceiling to get the last one. Been quiet after getting that one.

This client has not heard anything since I set up, after hearing it off and on for six months. I don't do bugs, but had to get rid of some wasps to work in the dormer area - makes me wonder if that might not have been what he heard? He said he usually heard it about 9 pm which would be shortly after dark. Any chance to this was it?