Insulation?

MountainDon · August 22, 2007, 12:39:55 AM

Re: Rodents.

I've done a lot of searching for methods of preventing rodent (mice) access into an insulated floor space (from the bottom). 1/4 inch hardware cloth has been suggested in a couple places, but I have lost the bookmarks/links. My only objection to using it exclusively is the expene. But that would be better than having mice invade and having to redo it sometime later. I haven't yet decided how I will resolve the issue when I build.

From the NATIONAL PARK SERVICE RODENT-EXCLUSION MANUAL, MECHANICAL RODENT-PROOFING TECHNIQUES manual...

Use 19- or heavier gauge, galvanized, ¼-inch or smaller mesh hardware cloth to keep smaller animals (e.g., mice) out. Covering hardware cloth with metal window screening also keeps insects out.

glenn kangiser · August 22, 2007, 12:43:08 AM

Seems like a good plan but expensive.

August 22, 2007, 05:46:42 AM

Well............

I am still trying to come up with an idea that I won't regret in a few years so...

What do you think about sheeting the bottom of the joist with something like adventech, sturdifloor, treated plywood etc?

MountainDon · August 22, 2007, 09:24:13 AM

Sheeting the bottom of the joists with plywood would certainly be a good rodent barrier, taking care to not leave even any gaps as small as 1/4 inch. But then there's the problem of ventilation in case of moisture.

My cabin will be 14 ft wide, joists on 2 main girders set about a foot or so in from the sides. My thoughts have leaned towards sheeting the bottom of the joists between the girders with plywood or similar. Then covering the outboard ends of the joists, the area outside the girders with 1/4 inch hardware cloth, the smallest mesh I can find in stock locally. That's supposed to be tough enough and have a small enough opening to prevent mice from entering. My theory is that this will provide sufficient ventilation with the approx 1 inch air space between the fiberglass and the outside, lower plywood.

blackdog · August 22, 2007, 09:43:32 AM

I thought about going with plywood but I'm also concerned about lack of ventilation. I suppose a galvanized soffit vent with screening attached to the back (they have these in Home Depot) in each joist bay could aid in ventilation.

Back to my previous post... does it make sense to remove all the remaining insulation until I'm ready to do it a better way? The existing fibreglass has never been wet. It's only dirty, so I'm guessing I can reuse this stuff??

August 22, 2007, 09:52:40 AM

If the insulation has never been wet, has no evidence of mold I would not remove it. I'd replace the missing stuff and cover the bottom.

You might want to randomly pull some here ot there to check for evidence of mice. They do like to burrow in there and will leave droppings behind. In that case here in the SW I'd carefully remove and dispose of it all. That's because of the Hantavirus being prevalent here (spread my deer mice in my neck of the woods).

blackdog · August 22, 2007, 09:58:32 AM

There has been definate mouse(and bee and who knows what else) activity. Not sure if the Hantavirus is in my area (Northern Ontario, Canada). Guess I'll look into this Hantavirus. Thanks!!

glenn kangiser · August 22, 2007, 10:37:00 AM

I would leave the insulation if no reason to remove it. I have had 2 dogs die of cancer or at least red painful growing growths, from getting into insulation stored in the barn. Industry paid for studies say this can't happen. I know it did.

While relatively safe I wouldn't want to over inhale it or get it moving through my body.

MountainDon · August 22, 2007, 12:27:24 PM

Found in over half of the lower 48 United States. Outside of the continental United States, cases have occurred in the following countries: Argentina, Brazil, Canada, Chile, Paraguay, and Uraguay.

http://www.hantavirus.net/

http://www.doh.wa.gov/EHSPHL/factsheet/hanta.htm

http://en.wikipedia.org/wiki/Hantavirus

August 22, 2007, 02:11:48 PM

Ok. I've been concerned, as previously stated, about rodent intrusion prevention. I've put off serious further exploration into preventing their access. The cabin is yet to be built, but, Yikes!, I thought, my RV is a sitting duck!!

There are innumerable references to blocking all entrance possibilities with a variety or materials. Hardware cloth with 1/4 inch or smaller opening is frequently mentioned, but no specifics found so far regarding the underside of a cabin floor.

This may not help blackdog right now, but I'm going to gather as much info as I can and post a new thread regarding control. May take a short time as there are current projects/tasks in line already. But not too long. :-/

glenn kangiser · August 22, 2007, 04:22:44 PM

Don't forget steel wool in existing holes has been mentioned.

blackdog · August 22, 2007, 08:48:40 PM

Thanks for your thoughts guys.

MountainDon, like you my project/task list grows every day. I'll likely won't do anything this year and leave as is. When I do eventually reinsulate I'll carefully remove the existing batts as the Hantavirus sounds nasty and start fresh. Thanks!!

OldDog · August 23, 2007, 07:20:43 AM

I have found the 1/4" hardware cloth to be the lowest cost alternative.

blackdog · August 23, 2007, 08:23:22 AM

OldDog, lowest cost may not always be the best alternative. Having said that, and I haven't done the math, but the 1/4" hardware cloth will likely be my choice also. Got a rough quote (site unseen) for sprayed-in-place polyurethane foam. R-7 per inch. A little under a $1,000 CDN per inch for 840 sq ft. Typically 3 or 4 inches are installed. So I'm looking at $3,000 - $4,000 CDN!! This is my first quote for the sprayed-in-place polyurethane foam so I have no idea if this is an average cost. Seems a little pricey.

August 23, 2007, 09:16:46 AM

It's a pricey quote, but it's pricey stuff. But it does a great job at insulating and stopping air infiltration. A big plus. Lot of money though. :-/

The real question is just how much ventilation is required for a fiberglass insulated floor. That's the difficult thing to ascertain. So far I've found nothing about that.

Another approach would be to enclose the space under the cabin, run good solid skirting all around the perimeter turning it into a crawl space in effect. Then you'd only have to decide on whether or not to take the ventilated or the non-ventuilated crawl space approach. Ventilated is traditional, but there are locations and methods for doing a non-vented crawl space. Then you'd just have to rodent proof the perimeter. Rodent proofing a perimeter is a fairly straight forward task.