This initial posting is broken into 3 posts.
This is really a two part question; how to keep the rodents out of the cabin and how to provide adequate ventilation for the insulated raised floor. Finding a method(s) to prevent mice ingress to a cabin is fairly easy once the mouse is understood.
Control of rodent infestation is important, not only because they are "icky", but because they are carriers of the Hantavirus. Hantavirus has been found in about 30 of the southern most states, but need not be limited to those areas. Deer mice are ubiquitous. Fortunately human cases of Hantavirus are not all that common, however, the fatality rate is over 50%, even with medical care. Without hospital medical care death is almost a certainty. It's a virus, there are no antibiotics for it. Hantavirus information may be found on several websites. An informative website is
http://www.hantavirus.net
Mouse Specific General Info
Mice are the most common rodent found infesting a building. Deer mice, the most common found in the outdoors around the USA normally only breed over a 4 month period. If all the progeny from a single pair survived and bred that could result in up to 800 mice. Fortunately up to 90% of the young become tender snacks for owls, foxes, etc.
Mice are exceptionally agile. They can jump 12 or more inches straight up from one flat surface to another. Jumping against a vertical wall they can reach even greater heights. They can jump down to the floor from an elevation of 8 or more feet without injury. They can climb any slightly rough, vertical surface, such as wood, plaster, brick, metal pipes, wire mesh, and cables. In addition, mice have good balance, and can easily run along horizontal electrical wires, ropes, and cables from one part of a building to another.
Mice are actually somewhat smaller than they appear, and they can squeeze their heads through holes only about ¼ inch in diameter. After getting its head through a hole, a mouse has no trouble getting the rest of its body through.
Mice will eat almost any foods consumed by humans and domestic pets. A mouse's daily food requirements are small, only about 1/10 ounce (½ teaspoon) of food and 1/5 ounce of water per day for survival, and much of their water requirements can come from the food they eat.
Mice occupy a home range area of about 1/3 acre to 4 acres, and they may travel 200 or more feet from the nest to a food source. They do not hibernate, but they are less active during winter.
Mice are strongly attracted to the warmth, shelter, food, and water offered by structures occupied by humans.
Guidelines for Preventing Access
With the above knowledge it is obvious the cabin could be under attack from top to bottom. All openings should be either sealed or blocked with an appropriate barrier. Check the siding, eaves, soffits, cornices, gables, porches, chimney or furnace clean-out ports, dryer vents, and all other external areas for cracks or holes that are ¼ inch or larger in size Darkening the interior during daylight hours and carefully inspecting around and under doors and windows may reveal gaps.
Ideally there should be an 18 inch or wider vegetation free zone around the perimeter. Grass should be kept mowed.
EXCLUDING RODENTS
Most small holes and cracks in building siding can be filled with caulking.
Larger holes may require filler before caulking is applied. Expanding foam is sometimes recommended for sealing around pipes, etc. However, I found several references to mice blithely chewing their way through the foam on their way to greener pastures. If the mouse thinks there may be food on the other side it will chew its way through.
Steel wool may be used to fill voids, however in the presence of moisture it will rust and disintegrate. A better choice would be stainless steel or copper scouring pads. Cement mortar is an excellent material to prevent chew through. Plaster or drywall though is quite chewable. If you are dealing with copper pipe or iron/steel pipe use a similar metal as stuffing to discourage galvanic action.
Pay particular attention to electrical and other service entrance points. Chimney guards should be utilized. All vent opening should be screened. Use ¼ inch or smaller hardware cloth. Do not use insect screening. Insect screening may be added as a precaution against insects, but it will not deter a rodent. Door thresholds and door sweeps should be metal.
What About The Floor??
For this I assume you are like me and will be using fiberglass insulation rather than a sprayed in place foam, because of costs involved and the fact that it is not rodent proof. On the other hand because foam seals air tight so well, the mouse may not smell any food on the other side and not even try. Who knows for sure though?
To keep mice out of the floor insulation hardware cloth may be used as a barrier. Hardware cloth must have ¼ inch or smaller openings to keep out mice. It should be galvanized after the cloth is woven or welded. The wire used should be 19 gauge or larger. 19 gauge is 0.0359 inch (0.9116 mm.). That meets the IRC 2003 requirements for ventilation screening. My research did not find any ¼ inch mesh made from any larger gauge of wire.
My big question all along has been how to seal the floor against rodent intrusion and provide insulation at the same time. I don't want to replace the rodent problem with a potential mold problem. I have searched online, I searched in the library, I have spoken with my local building department. I have found no suggestion other than to either..
[A] Cover the entire underside of the floor joists with hardware cloth. That will ensure adequate ventilation.
Enclose the space under the building (a regular crawl space), ventilate it according to code and stop the rodents at that point. The insulation would just have to be retained in the cavity. This can be achieved by using specially designed snap in place wire retainers or some other method such as inexpensive chicken wire, etc. This will allow ample floor insulation ventilation. Crawlspace ventilation usually requires a minimum of 1 sq ft. of vent area to each 150 sq ft of floor space. There are conditioned, non-vented methods of crawl space closure, but that's beyond the scope of this discussion.
When enclosing a crawlspace that is not a poured concrete, or a concrete block and mortar foundation there is another special consideration regarding rodents, as well as all the above about sealing openings. That is rodents like to burrow. If a skirting is simply installed around the perimeter to ground level, or even slightly below grade they will burrow under. The good news is that most animals will try to dig down right adjacent to the wall. If they encounter a barrier they will give up.
Such a barrier may be made using hardware cloth. Bend a strip into an L-shape. One leg should extend upwards 5 to 6 inches above grade. The lower end of the L-shape should be buried about 2 inches. It should extend horizontally at least 6 inches from the building wall. The edge against the wall should be securely fastened to the building. The horizontal leg should be firmly staked to the ground every foot of length and then covered with 2 or more inches of soil or rock. This should deter any of our native rodents. Old world (imported) rodents may be more aggressive and may require concrete walls up to 24 inches deep in the soil. Other materials such as galvanized metal may also be used. Keep in mind that some soil conditions may cause corrosion of even galvanized metal.
Any building using vertical metal panels with ribs or corrugations requires special attention to sealing the openings between the bottom of the panels and the bottom framing. That's an area that is apparently overlooked by many.
None of the information I checked mentioned the use of sheet aluminum for rodent exclusion. Perhaps it is too soft to prevent gnawing through?
So What To Do?
My original thought was to cover the underside between the main girders with plywood sheathing or pegboard. Then use hardware cloth along the long sides, between the girders and the outside wall. A concern about the pegboard was the holes providing points where a mouse could begin to chew its way through. I was also concerned about using OSB as any separation of the strands could give a determined rodent a place to start. They are prolific gnawers. Plywood seemed a better choice. A cement board product would be even better.
So with all the above in mind, I am prposing to cover the entire underside of the joists with ¼ inch mesh galvanized hardware cloth. The cost is comparable, maybe even less if 5/8 or ¾ inch plywood was used as the primary under joist material. Eventually skirting the cabin using rodent proof techniques could be applied.
I figure 48 inch wide hardware cloth would be ideal for handling. Unfortunately I have not found any 48 inch wide stock in my local area, except for 10 foot lengths. Two foot width, ¼ inch mesh in 25 ft rolls is common for some reason. I have found a couple of online suppliers. One stands out for better pricing. The shipping will add to the cost of course, so it comes out about 10% higher than the local stuff. However it can be had 48 inches wide and in 50 or 100 foot rolls, which is an installation plus.
http://www.hardwareandtools.com/icat/14inchmesh
There may be other good value suppliers. If you find any please post. Also please add your successes, your failures, your ideas/thoughts.
hello all.I have been reading and enjoying the forum about one year or so.never posted before so here goes.property like ours common to our area in upstate ny is somewhat difficult to build on. .i.e difficult access, steep ridges, heavily wooded, limestone karst with poor perk,electric lines brought in at high cost etc.the good though is clean air, good water most places, low population, reasonable taxes,sawmill lumber, beautiful landscapes etc.we have owned our wooded acreage for a few years.sometimes waiting to get started is a good thing,plans sort themselves out.more on our project soon. with hard site enviorment foundation building gets difficult and costly so piers can work well.Insulation under floor with tough winters,snow, low temps, moisture problems are cause for real concern on cabin longevety and comfort.our solution might be building on frost protected piers with limestone infill between piers, free from our site.crushed stone under cabin with barrier under stone for weed and moisture control. vinyl soffet strips nailed under floor joists perf style,comes in 12 ft. lengths with J bead around perimeter.waterproof and durable.drill holes and blow in batts i.e. bibs for good R value. any thoughts on this thanks all
Welcome to the forum, nyvinny. Seems like interesting land conditions. There are a million ways to do things and if it seems like it will work it probably will. :)
Great post Don! What you really need is attached.
Bruce
Any thoughts about using vinyl soffet material nailed horizontaly across floor joists from underneath.12ft. length available with J bead channel around perimeter.T channel to join spans longer than 12 ft.Center of clip together strips is perforated the whole 12 ft. length for venting insulation. waterproof and durable, no paint needed ,no rust like hardware cloth.
http://www.reesewholesale.com/catalog/siding%20vinyl.pdf
Pricing seems to be about .70 per square foot plus channels. Could be a bit expensive but should work.
http://www.amazon.com/gp/product/B0009H2OHQ/ref=nosim?s=merchant&m=ATIVD58EVJCS&v=glance&tag=nextag-tools-tier5-20&creative=380341&linkCode=asn&creativeASIN=B0009H2OHQ
1/4 hardware cloth 300 sq ft $78.39 = .2613 cents per sq ft. About 1/3 the cost for something that will not be seen anyway. :)
Glenn, I don't want to seem like I'm nit-picking but that roll of hardware cloth is 23 gauge. All the info I ran across states that it should be 19 gauge. The 23 gauge would more than likely deter but maybe it isn't heavy enough for larger rodents, larger teeth. Just guessing. :-/
Pete. A couple of cat snipers like that should certainly discourage the marauding mice from taking up residence. ;D
nyvinny, that soffit material could very well do the job. But it's do difficult to find information about covering the joist bottoms, and how much venting would be recommended. I'd be wondering about that. It works well for soffits I think because there is a positive air flow set up by having higher exit vents (gable or roof). The heating of the air in the attic gets the flow going easily.
Maybe I worry too much about under the floor venting. It's been said before in other threads, other toics, that sometimes we theorize and think too much.
My one neighbor with a completed cabin built on piers left the underside uncovered, but did skirt the perimeter quite well. He mainly used galvalume coated steel roofing panels for the skirting.
I know myself, and how I complete tasks. Even though I want to skirt the cabin, I don't think I'm going to get it done right away. I'm planning on having storage space underneath... one end of the cabin will be somewhere between 3 and 4 feet above ground level due to the slope. Having doors into the underside space is just another mouse access point to have to worry about, hence my desire to mouseproof the joists. The need to keep mice out is at cross purposes with that at times. :-/
If you can wait to do the insulation until the house is out of the weather and the framing is dry, then there not a need for a great deal of ventilation on the bottom of the joists (but you do not want to seal it tight). On our tiny cabin we used black poly stapled over the bottoms of the joists to hold the batts and then punched slits with a razor knife to vent any trapped moisture. We do not have skirting and critters have not been a problem.
The clever idea for wire cloth on the bottom of the joists makes sense when you have to insulate from above and before things will be dried out.
My teeth are not even good enough to get through the 23 gauge, Don but a rat with a good set and determination might. :-/
Rats were what I was thinking of. Brown rats are just about everywhere except Antarctica.
If rats were the only concern you could get away with bigger 1/2 inch mesh
I bought 4x8 sheets of 1/4 inch masonite pegboard and nailed/screwed it to the bottoms of my floor joists. Snow blows underneath the cabin in winter but all of the pegboard is still there ... My cabin is out in the Wyoming mountains and no mice have gotten into the insulation between the joists. It's been there for about 5 years now. So far so good.
Hey Hal! Good to hear from ya'. Also good to know the pegboard worked well.
nyvinney; I used vinyl soffit as you suggest. I got most of mine free (mismatched and broken pieces from a friend in the business so cost wasn't a concern.) it's only been there since last fall but all seems ok so far. No signs of rodent infiltration or moisture concerns. I keep my finger's x'ed. I doubt I'd use soffit if I was buying it all. I don't think it warrents the expense.
Excellent post MountainDon. Appreciate all the research you've done. The heaviest gauge of 1/4" I have found both in my local stores and on the web is 23 ga. Is 19 ga 1/4" even available? I believe the 1/4" you linked to is 23 ga. Here is the suppliers (Jackson Wire) spec sheet http://www.jackson-wire.com/jw-specificationsheet.html.
For me the best price I can do locally is $75 CDN for 36" x 50' roll. They don't stock 48" wide rolls :(. Too bad, it would be perfect for 16" oc joists.
Here is an online retailer out of California I came accross http://www.twpinc.com/twpinc/control/category/~category_id=TWPCAT_MICE. They offer decent discounts for multiple roll purchases. However, for me the shipping charges to Canada would be almost as much as the product.
Blackdog, thanks. A couple of additional notes and things.
1. All the most complete rodent proofing info I was working with recommended the 19 gauge wire. But none recommended a source.
2. I've just recently been working with some 1/4inch 23 gauge hardware cloth I had laying around. I'm fashioning a back support for the rock perimeter under the gazebo sides. It seems to be quite robust. I'm thinking that the 23 ga. would be quite fine for most rodent purposes. Maybe something like a beaver would be able to make it through. :-/
3. I was certain I found 1/4 inch mesh, 19 gauge hardware cloth. I had another look and yes, I did find some, but only on a manufacturers site. No retail sales. Also no links to where you might buy it. It may just be available to wholesalers on special order I don't know. :'( :-[ :-[
4. That website http://www.twpinc.com/twpinc/control/product/~category_id=TWPCAT_4/~product_id=004X004G0350W48T does have 20 gauge, but it's way more $$$ than 23 ga. It's interesting to note that they list the 23 gauge as rodent/mouse proofing material.
So let's say 23 gauge would be fine. :)
I agree, 23 ga should do the trick. I boxed in my woodstove chimney (the elbow area between the wall and soffit) with 1/8" 27 ga. Even the 1/8" stuff is pretty tough and I'm thinking that may work but I'll likely use the heavier 1/4" when I reinsulate my floor.
As a side note - When I was at my place last week, I caught 6 deer mice in snap traps baited with peanut butter. 5 on Saturday and 1 on Thursday and nothing the rest of the week, so hopefully I got them all. What was supposed to be a week of fishin' turned into a week of going over my cottage inch by inch plugging entry points with steel wool and caulking. I'm certain I've filled all the entry points but only time will tell.
I just got done shooting a possum in my chicken feeder. He ripped a bunch of feathers out of the chickens then went on about his business until I showed up. I guess some good 23 gauge would be in order there too. Either that or a 12 gauge. I just used .22 cal.
Irrelevant -- nevermind. Still a critter.
Good trapping!!
Here's a mouse trap I like. No wood, a no touch mechanism.
(https://i133.photobucket.com/albums/q75/djmillerbucket/oddsnends/snap-e.jpg)
http://www.kness.com/Shopping/shopdisplayproducts.asp?id=1&cat=Mice
I've also seen them on Amazon.com
Can't forget my grandpa's trap from the free stuff section. Could fit here too for those who want to catch something live. He also made a mouse smasher model with a 6x6x6 or so block hanging over the trigger paddle.
(https://i35.photobucket.com/albums/d184/glennkangiser/boxtrap.jpg)
Hmmm. With a little modification that could be a real guillotine. (need an evil grin emoticon) :)
Open the back end - bait properly -- they could remove their own heads.
My dad used to use them to trap skunks. They then drove them to a park about 10 miles away to humanely release them.
They said that often the skunk would beat them back home. :-?
Note that the skunks couldn't get their tails up to spray in the small box.
MountainDon, I was thinking of another possibility. Not really sure if it's doable and could get pricey, but critter proof.
I have read (maybe even on this site) of people sandwiching some STYROFOAM extruded polystyrene insulation between a top and bottom subfloor.
Lay your 5/8" or 3/4" T&G subfloor on the joists as normal. Next put down some 1 1/2" STYROFOAM followed by another subfloor (say 1/2"??). Where the plans call for a wall, replace the 1 1/2' STYROFOAM with a 2x. Floor could be a little spongy and will only have a R value of 7.5.
There's some interesting reading on wire mesh in this on-line catalogue:
.
http://www.mcmaster.com/
.
... just type in "wire mesh" in the search window, and then click on "about wire mesh".
Quotesandwiching some STYROFOAM extruded polystyrene insulation between a top and bottom subfloor.
Not to rain on your idea, I had thought of that. But discarded the idea because...
1. Not enough insulation value for my purposes.
2. Seemed expensive for insulation value.
3. Potential sponginess bothered me. I'm used to hard unmoving, unforgiving concrete slabs.
4. The strength of the perimeter walls to rim joists really bothered me. Or the strength could be achieved, but at greater expense and bother.
5. It seemed more work than what it was worth, along with #1 thru 4
JMO
QuoteThere's some interesting reading on wire mesh in this on-line catalogue:
More information there about wire and other mesh than one could imagine. :)
"Mice will eat almost any foods consumed by humans and domestic pets. A mouse's daily food requirements are small, only about 1/10 ounce (½ teaspoon) of food and 1/5 ounce of water per day for survival, and much of their water requirements can come from the food they eat."
If they don't eat any more than that what is all the fuss about? ;) Seems like no matter what I do they are a fact of life in the country. In the better mousetrap contest a 5 gallon bucket half full of water was a serious contender. The critter attempts to get a drink, drops in and can't get back out. Eventually drowns.
I have little packrat homes scattered around my place in the hills. I have gone there after a fairly long absence and found Bobcat droppings on my steps. But then I am way out there where the buses don't run.
Upgrade that bucket, desdawg with a horizontal wire - stiff like welding rod, with a corn on the cob - hole drilled longways so it will rotate on the wire -- smear it with peanut butter and give them a plank to walk up. It will be flying Walenda mouse into the the water when he falls off the rotating corn.
Cool! ;D ;D
Glenn, now that's some Okie Ingenuity for sure!!!
Des, I agree, don't see what the big deal is. Mice have been a fact of life for me since I was a kid. When I was born, we lived with my grandad and he was a sharecropper. My uncle and I slept on a screened in porch with a lineoleum floor. I can still remember hearing the sound of little mouse feet clicking across that linoleum after the lights were out. Actually, that's the only good reason to have a cat! We called a good cat, a mouser and they always had a home with us.
Okie Bob
Well, I'm sure there are a lot of folks who have had or have mice in their houses. The fact is they can be destructive as well as disease carriers.
Yes, they don't actually eat very much food, but any food they get into, well, I consider it contaminated. They can get into anything not in a metal can. Unlike people they are not fastidious about where they defacate or urinate. They also chew stuff in the walls and ceilings like insulation on wires. Maybe not so much as they used to before romex, etc. They love to nest in fiberglass batting. Unlike people, burrowing through it doesn't bother them.
Maybe I'm more cautious and concerned because I lived through a case of Hantavirus. The deer mouse is the primary vector. Now, I will freely admit that the vast majority of folks have absolutely no worry about catching the Hantavirus. I believe I picked it up after a summer of prowling around old mines, cabins, ruins in SE Utah in the late 90's. I slept in some of the old cabins and that's the most likely place I got it. I foolishly swept the floor area for a place to bed down and likely stirred up droppings/urine/virus doing so.
So as I stated, most folks have nothing to worry about regarding hantavirus. But, IF you get Hantavirus you will almost always die unless you get to a hospital ER/ICU. Even then it's a crap shoot. It's a virus, no drugs work on it. All the hospital can do is give support; oxygen, fluids, a respirator if necessary. The case fatality rate in the entire United States is now 35%, New Mexico 41%, better than the 56% rate a few years ago. The time from beginning to feel a little under the weather to having severe respiratory distress can be measured in hours rather than days.
I rest easier if I know I've done all I can to keep mice from ever gaining access to a building. FYI, even a HEPA filter is not fine enough to filter out the virus, vacuuming just blows any virus present throughout the area.
'nuff said.
So everyone makes their own choices, takes their own chances. To each his own.
NATIONAL PARK SERVICE RODENT-EXCLUSION MANUAL
available here
http://www.health.state.nm.us/epi/hanta.html
D/L link near top of left side
QuoteGlenn, now that's some Okie Ingenuity for sure!!!
Des, I agree, don't see what the big deal is. Mice have been a fact of life for me since I was a kid. When I was born, we lived with my grandad and he was a sharecropper. My uncle and I slept on a screened in porch with a lineoleum floor. I can still remember hearing the sound of little mouse feet clicking across that linoleum after the lights were out. Actually, that's the only good reason to have a cat! We called a good cat, a mouser and they always had a home with us.
Okie Bob
BoB -- you could have trimmed their mousy little toenails and they wouldn't have clicked on the linoleum and woke you. :-?
Dang, Glenn, why didn't I think of that??????????
Okie Bob
Actually I was being facitious. I don't like the little suckers any better than anyone else. But they are very difficult to keep out as they seem able to penetrate any fortress. I lived in the city for a while. Didn't have much problem with rodents but enter the sewer roach. The cock-a-roach is a prehistoric pest.
So I guess I will settle for the country and if it comes with native pests I will just do my best.
Glenn, it sounds like you have perfected the bucket technology. :)
I'll forgive you, BoB. I'm sure it was before the days of the "mouse huggers". ::)
desdawg, I wish I could claim that as my own invention --making the little suckers fall in and drown -- but I read it somewhere.
No wonder Mickey Mouse has that high squeaky voice. Probably straddled the wire when he fell off. Wonder who helped him out of the water. :-?
How fickle I am. Love them one minute -- drown them the next. :o :)
Here's a few links for variations of the bucket trap...
http://asktrapperjohn.com/topics/bucketmouse.htm
http://www.4dotranch.com/MT/index.html
http://www.wikihow.com/Build-a-Mouse-Trap
(https://i119.photobucket.com/albums/o137/Wetpaws07/Mousetrap.jpg)
Now that is my idea of high technology. And with two ramps the party could get bigger.
Some people have had success with the plug in the electric socket mouse sound deterents.
My thought is on bottom of an open pier cabin, how about metal roofing if money is not an issue. They interlock and should seal
out any rodent. Then from the inside, spray one inch layer of spray foam which is an air barrier, then fill with fiberglass, the put sub-floor on. Not sure how moisture is an issue if off the ground on piers - but maybe others can comment.