Humane De-squirrel-fication at the Mansfield House

There are only two kinds of homes: Those that have squirrels, and those that will get them. Okay. I’m sort of joking here. But a good many old (and new) homes are prone to invasion by critters. Sometimes, it’s the result of poor construction or repair; but very often, deferred maintenance or inattentiveness by owners or occupants are the main contributors. I’m first to admit that, in my past, I’ve been guilty many times of the last two violations. But nowadays, I’ve no tolerance for preventable failures, don’t allow myself to perpetrate them, and don’t hesitate to make others aware of such situations whenever I notice them.

The authored geared up to squirrel-proof the attic.

The author assumes many roles here; today, it's that of Squirrel Exclusionator.

The Mansfield House, of course, has been no stranger to critter occupation. In the short time I’ve been here, I’ve discovered a bat living in my cellar, a possible skunk in the crawlspace, some ancient evidence of past raccoons, both ancient and more recent evidence of mice, and just very recently, two gray squirrels, who were regular sojourners in my attic. The main entry points for these squirrels (based on my neighbor’s eyewitness reports) were several openings along the roof’s ridge line:

Opening in ridgeline just at the north gable

An opened portion of the ridge, right above the north gable's rafter peak.

These openings had resulted from an uncompleted roofing job done not too long ago for the previous owner, where some sheathing boards were replaced or moved, and the ridge was never capped. An errant subcontractor had been blamed, but that’s neither here nor there, at this point. I’d been an idiot to not have checked closer back in January, as none of this is easily visible from the outside. I just assumed all had gone well with the recent work (again, the sin of inattentiveness on the part of an owner). So let this be a lesson to never trust, and always meticulously verify, even if you’re convinced verification is unnecessary, or not worth your time.

Anyway, my strategy for getting the squirrels out was to close-up the obvious openings in the ridge, and one or two less obvious, older openings that I’d suspected might also serve as potential entry points. Then, catch the squirrels with live traps and release them to the wild [not exactly something I'd never done before -- some of you may recall my post "Hey Rocky, Watch Me Pull A Squirrel Outta My Attic (Again?!)", and the more whimsical "Squirrelly Goings On At Building Moxie And Beyond"]. There was, of course, quite a bit of urgency here, given the nonstop damage that squirrels inflict on the interior of a building, and the fact that grays in these parts tend to breed toward late spring, which was not too far around the corner:

Wood window with squirrel damage

Squirrels love to chew sash muntins and other elements of wooden windows, especially where there's light entering and a clear view to the outside. This photo shows the damage they did to my attic window at the south gable end. The window at the north gable was actually protected by its overall reduced exposure to sunlight, and the relative dirtiness of its panes (sometimes, not cleaning something for a while has its benefits).

So, I set about the exclusion phase first, by cutting a number of 15″x swaths of metal lath to length, forming them to the underside of the ridge wherever there were opened areas, and then stapling them in place:

Metal lath fitted and stapled over the opening in the ridge at the north gable.

Metal lath fitted and stapled over the opening at the north gable.

Often, fitting the lath required trimming or rounding the edges where the lath was inserted just above, or butted up against, the rafter peak:

Trimming one end of the metal lath with tin snips.

Trimming/shaping one end of the metal lath with tin snips.

The largest of the openings in the ridge was at the opposite end of the attic, just at the south gable. Here it is, finally covered:

Exclusion work at the ridge opening at the south gable end.

Exclusion work at the ridge opening at the south gable end.

Now, here’s one of the much older and funkier potential critter entry points in the attic. The sunlight visible at the extreme left of the photo below is an opening to the exterior of the house, where the rear top plate of the frame penetrates the gable siding (and has done so for nearly 300 years now — nothing new). But the small line of light just below the foam board is an opening into the north garret. Yes, that’s right; warmed interior air leaks upward into the attic past the foam insulation, right at this point. But at least it’s nothing to worry about from a critter-entry perspective:

Light entering from the exterior and south garret ceiling.

Light entering from the exterior, and from the south garret.

Looking more closely into the opening, just above the plate and to the left of the rafter that defines the north rake of the rear roof, revealed a chewed up plastic bag. Perhaps the squirrels had gone out shopping at one point, and then attempted to use their plastic shopping bag for sealing out winter drafts:

A chewed up plastic bag left behind by squirrels, down in an opening to the outside of the house.

A chewed up plastic bag left behind by squirrels, in an opening to outside the house.

So I took a strip of metal lath, and formed it into a cone:

Metal lath rolled into a cone.

Metal lath rolled into a cone.

Then pushed the cone down into the opening between the plate and the rafter. So this potential entry point is also now excluded:

Metal lath cone now blocking an irregularly shaped potential entry point.

Metal lath cone now blocking an irregularly shaped potential entry point.

Finally, when I’d completed all the exclusion work I’d determined was necessary, I set the traps. But, I’d hoped that maybe I’d lucked out when it came to actually having to capture them. You see, this particular pair of squirrels seemed to be in the habit of spending long periods of time away from the house. Usually, whenever they happened to be around, and I entered the attic, they’d scamper under the floor boards. But their presence down there was still quite audible. On other occasions, when I entered the attic and was greeted by dead silence (no matter how loudly I tramped across the attic floor), I surmised they had left for a while.

On the day I’d done all the exclusion work, there was total silence in the attic. So I was hopeful they’d gone off on one of their squirrel jaunts, and I’d get all the openings sealed before they returned. But when I’d finished, I baited my Havahart live traps for them, anyway:

Havahart live animal traps.

My Havahart live animal traps. I use chunky peanut butter for bait, with a few spoonfuls of sugar mixed-in to prevent the squirrels from going into shock from lowered blood sugar levels, as a result of their stress from being captured. I also leave a pan of water in each trap, although this often gets knocked over. If I catch a squirrel, I'll cover the trap with a towel to mitigate further stress, bring the trap outside, and release the animal. (Oh, and I always wear heavy leather gloves when doing this, just in case).

But over the past few days, I’ve caught nothing in my traps. And the attic is silent. So maybe my supposition was correct. Or maybe not. There could always be other entry points I’m not aware of. We’ll just have to see over the next few weeks whether the squirrels manage to make it back in. But I hope they’re gone for now. They’re much more appealing when they’re frolicking about in the back yard, rather than running amok in the attic. :)


Now that the squirrels seem to have been successfully excluded from the house, my next step is to temporarily cover the ridge from the outside with ice & water membrane, just to keep the weather out. Since my longer-term objective is to properly vent the ridge (as part of a broader and precisely controlled system of attic ventilation), the fact that the ridge wasn’t properly capped might very well be to my benefit, since it’s work I’d have to undo, anyway. But what I’m really concerned about is how much moisture got in during the time the ridge was opened. Some cursory scans of the sheathing boards forming the ridge show a relative moisture content of about 7%-9%, so the boards are actually in pretty good shape. Undoubtedly, this is because they’re able to dry out quickly enough, following any soakings. But I’ll also be checking for moisture under the upper courses of shingles and underlayment, as well.

Although no squirrels were caught, this effort did yield a quarry of sorts, consisting of a few interesting old iron nails I’d extracted from the sheathing boards in a few locations where they would’ve blocked the lath:

Tools and old nails.

Tools hung up for the day, and our quarry of old iron nails.

Most of these nails had once secured sheathing planks to the rafters, but were gradually pulled out as the rafter pairs shifted over time. Three of these nails appear to have been clinched against their planks. The small nail, third from the left, I believe to be an old shingling nail used on a wood shake. The nail in the center is a 3″ machine-cut nail, identical to the ones I’ve found extensively throughout the Hawkins House. Finally the nail at the extreme right is a true hand forged nail — both its shank and head had been completely shaped by a blacksmith.

Old iron nails.

Old iron nails extracted from sheathing boards.

So, I hope you’ve all enjoyed this article of squirrelly and critter mayhem. It’s not the first I’ve written on this topic. And I’m sure it won’t be the last….

About John Poole

My interests include historic homes, architectural preservation and restoration, improving the energy performance of old houses, and traditional timber frames.
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11 Responses to Humane De-squirrel-fication at the Mansfield House

  1. Hmmm, those wire’s are to hard to cut with their wire snippers, might have to see if we can retrofit the jet packs with a plasma cutter… Thanks John : )

    In all seriousness, great choice of methods & choice in materials (though we don’t expect anything less from you). I got a feeling you’re supposition about the quick drying (and the older wood with the tight grain) is probably going to be the case. Now do my eyes decieve me, or is that a Retrotec Duct Tester you got now? Very cool & I hope you had a great weekend

    • John Poole says:

      Thanks very much for the good words, Sean. I really appreciate it. But wire snippers? I think all you need to do is put little metal jackets over the squirrels’ teeth, and just let them chew away. Or maybe not even. Heck, your squirrels could readily pull those staples out without even breaking a sweat!

      And yes, that’s a Retrotec DU200. But I’m not planning to blast any ducts with it any time soon. Rather, I’m building a few custom “pressure pans” (if you will) for fitting over whole windows, and I’m going to attempt to use the duct blaster to measure before and after leakiness of specific wooden window restoration and weatherization techniques I’ll be working on this summer. It’s all a part of my master plan to figure out the best possible way to achieve energy efficient and durable wooden window retrofits and have the numbers to back my claims up. But that, of course, is a whole ‘nother project unto itself!

  2. Amy Good says:

    I couldn’t resist thinking that your “friends”…errr…Sean and I’s friends were hiding out, as trained, to get a better understanding of what you were doing so they could remove it when you left, thinking all was well with you repair.

    Seriously, interesting take on the attic exclusion. And I like the level of detail you go into to teach those that have the same issues.

    Have a good one!

    • John Poole says:

      Thanks, Amy! I was wondering what all that muffled snickering was, as I was working away…

      Glad you liked the post, and hope there were some useful take-aways of some form or another. (Though I don’t wish squirrel invaders on anyone, of course!)


  3. John Leeke says:

    Years ago I learned an important fact about squirrels and buildings from the Squirrel Man of New Sharon, Maine. This was a fascinating thing to learn as I helped a client solve a squirrel problem in their fine old house.
    This past fall I was reconstructing and repairing the cornice on my own front porch, in Deering Neighborhood, in Portland, Maine. I had the boxed-in cornice open for about two weeks during October and early November. Among many other repairs I had spliced in a new piece of pine board onto the soffit and the next day I noticed little animal foot prints on the new wood, and, of course, it did not occur to me what I had learned from the Squirrel Man of New Sharon. So I carried on, closing in the cornice, making sure there were no squirrels inside, and installing new sections of hand-made wooden gutter, with lead flashing. The gutter were finely crafted out of 4×6 coastal white cedar, by my self and my wife, who helped me pass the three sections of gutter over the table say 73 times to “step-kerf” the matching profile of the original gutters finishing them up by hand-planing with wood-stocked rounding and hollowing planes. The work on the cornice was looking fabulous and the warm weather continued into November as I completed the work with upteen coats of various preservatives, primers, sealants, topcoats, etc. It was finally all done late one evening. The next morning I got up and look out my second storey window to view my handy work. Sitting right there in the gutter was a squirrel chewing a big gaping hole right into my fine wooden gutter! Not only that, but he had also chewed up about 3′ along the edge of another section of the gutter. I tell you what, I grabbed my son’s pellet gun and marched out there with vengeance in my eyes. The squirrel was still there, and as I drew bead on him, it just happened to occur to me that if the new neighbors happened to be watching they were probably also calling 911 to report a gunman aiming rifle at my house. Well, I lower my weapon, and lurked back into my house to cool off and contemplate the situation.
    I wracked my brain to recall exactly what I had learned from the Squirrel Man of New Sharon, Maine. I was at a loss. I looked up in my old client’s file, and there was my note: “Visited the Squirrel Man of New Sharron, we will do what he says.” But, no notes on what he said. First I thought of shoot myself, then I tried calling my old client, they had moved. That was a dead end. Later than night was still fuming about the gutter, the squirrel and my own stupidity. I finally fell asleep and dreamed about the fun of making more gutters (actually, for me, that would be fun), which turned into a nightmare about shooting squirrels who took vengeance upon me and my house, and, well we don’t have to get into the entire nightmare, which was not a pretty scene. In the morning I woke up with a revelation of what the Squirrel Man of New Sharon had told me: “Do not include or exclude a squirrel by sealing up their holes of entry, particularly if the squirrels may have food stowed away inside the building, which they almost always do. The squirrel will always remember that there is food in there and will chew his way back in to get it. The thing to do is first get rid of the squirrel and then repair the holes.” The Squirrel Man of New Sharon’s main point was that you had to get the individual squirrel, who had put his food in there.
    So, we set up a program of trapping and relocating squirrels. To date (April 4th) we have trapped 15 squirrels, and I’m betting that we’ve gotten the one who was messing up my porch work. Now for another round of porch repairs.


    • John Poole says:

      OK. I nearly fell off my chair, multiple times, while reading that. Especially the dream sequence part. Fantastic!

      Is/was the Squirrel Man of New Sharon an actual, living guy? Or an ethereal spirit who somehow channels divine knowledge to you, just when you need it? Perhaps he has actually just channeled that knowledge to me, via you (and the Internet, of course). (“When the student is ready, the teacher will finally appear”).

      So, I’ve clearly violated this important teaching of the Squirrel Man of New Sharon, and might very well be paying the price for that right now, unawares. The only thing I can say in my defense is that I keep my traps set and nothing gets caught, and I shall continue to do so until I finally, finally, am confident they’re not returning. (In past, when I’ve been successful at catching these guys, I’d drive them a good number of miles away to a local state forest to release, hoping that that would minimize the chance of their returning and finding another way back in).

      But one can never be overly confident of what seems like momentary success in excluding these reprobates. One must remain forever vigilant. Oh yeah, and flip the breakers on all nonessential circuits running through the attic (in my case, anyway).

      Thanks for this great account, John!

  4. John Leeke says:

    The Squirrel Man if New Sharon was a real person.

    Perhaps a trap inside and a trap outside would serve the Squirrel Man Of New Sharon’s theory.


  5. John Poole says:

    Today (4/25/2012) I spotted a squirrel hovering wistfully above his former favorite entry point, which I’d blocked off nearly one month ago. He hung around for a few minutes, generally quiet and perhaps confused, then scampered off. Based on some of the comments posted above, however, he’s most likely hatching a plan to recover his stash. While I’ve found no obvious indication of any further critter infestation, it’s clear that eternal vigilance is the price of freedom (from squirrels). :-P

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  7. John Poole says:

    The dust mask kind of looks a bit like a squirrel snout, doesn’t it? :-D

  8. John Poole says:

    I can’t account for John L., but I for one, am definitely squirrel crazy. Plus I have bats in my belfry (not to mention one or two in my cellar). But then, you already knew that….

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