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driedjello
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# Posted: 23 Aug 2009 22:12 - Edited by: driedjello
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I love this forum but have not found a thread talking about the proper way to insulate a floorbox.
I am building a 12 X 24 foot cabin on a slanted hill right next to a lake. The piers will vary from 1 to 5 feet as a result. This will expose the floorbox to a large volume of humid air. I live in Nebraska and we can have very cold winters.
I am looking for the best way to insulate my floor that will not attract insects/critters. I am worried that Styrofoam or other materials will be a huge draw for ants or wasps or a multitude of other colony based insects.
What would you all recommend? Many thanks in advace!
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swanugly
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# Posted: 24 Aug 2009 00:12
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i don,t know if its the proper way but here is what i did .
i nailed plywood strips to the bottom of the floor joist before i nailed them in place . the strips were about an inch wider on each side of the joist . once the floor joist were all nailed in place i cut plywood to fit inbetween each joist , i tryed to make it fit as tight as i could .( i guess i guy could seal all the seams to make it tighter ) laid the plywood in between each joist and then added the insulation .
it has only been together for 1 year but so far nothing has made a home in the insulation yet .
http://www.small-cabin.com/forum/6_108_0.html
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Modern Hippy
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# Posted: 24 Aug 2009 10:40
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The key to insect and critter control in the floor (or anywhere else) is going to depend on they're ability to access the floor and less on the insulation material used. If you're concerned about critters, I suggest using lattice with small holes or a hardware cloth with 1/4 inch or smaller openings to skirt the bottom of your cabin. For insect control, cellulose insulation with an impregnated borate based insecticide works great. I plan to build a cabin this fall and will use spray-in foam insulation due to its efficiency. I have managed a pest control firm in Florida for the past 10 years and I don't for seen any insect problems with foam insulation used above the soils grade. Always keep in mind that the key to insect and critter control is keeping your structure inaccessible and undesirable (to them). I hope this helps and good luck!
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Moontreeranch
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# Posted: 31 Aug 2009 10:08
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We plan to start our foundation work next weekend...ye haw. For Flooring insulation, I'm taking a step beyond swanugly's method. Instead of using ply strips to the bottom of the joist I plan to use TJI's for the floor joists (these are the man-made wood I-beams) the flange at the bottom will rest on the support beam and a 14" wide strip of ply (3/8) will lay between each joist resting on the top of the lower flange...insulation will go between joist...3/4 ply decking on the top of the top flange. by having the ply rest on the flanges it could still be removed if necessary since the floor load will be on the bottom of the flange. I plan to attach the 3/8 ply in the "bays" with finish nails so they will provide resistance but still be serviceable.
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coop
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# Posted: 12 Jul 2011 21:28
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HI all. I constructed a cabin in Massachusetts, fully winterized, and on piers. I sprayed closed cell foam between the floor joists, applied exterior grade plywood below that and then ran foil faced foam sheathing below that. Voila, real warm and no foundation. Just one problem in the process, I forgot to "box" the shower trap before spraying foam and had a frozen/shattered trap. Ok, no problem...dismantled the system, built a box within the floor joists around the trap to allow warm air to reach the trap then re-sprayed that area and restored plywood & foil faced foam. No problem since then and learned my lesson!
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toyota_mdt_tech
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# Posted: 12 Jul 2011 21:43
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Quoting: swanugly i don,t know if its the proper way but here is what i did . i nailed plywood strips to the bottom of the floor joist before i nailed them in place . the strips were about an inch wider on each side of the joist . once the floor joist were all nailed in place i cut plywood to fit inbetween each joist , i tryed to make it fit as tight as i could .( i guess i guy could seal all the seams to make it tighter ) laid the plywood in between each joist and then added the insulation . it has only been together for 1 year but so far nothing has made a home in the insulation yet . http://www.small-cabin.com/forum/6_108_0.html
Also, wrap the pier post with tin or stove pipe metal, this makes it harder for critters to climb up to gnaw a hole and get under your floor. I'd put a vapor barrier across the full underside when its all in in place.
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Borrego
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# Posted: 13 Jul 2011 16:59
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I did it the way swanugly did but used the yellow expanding foam insulation to seal any gaps in the ply. I used 3/16 luan ply which is supposed to be moisture resistant (?) Next time I would use the TJI's though for sure!
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Anonymous
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# Posted: 17 Oct 2012 19:00
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Regular fiberglass insulation will retain moisture and we all know how effective wet insulation is . I suggest closed cell foam ripped to bay width and of coarse some exterior grade plywood layed on cleats nailed on each side of each joist .
Works for me in northwest Wisconsin and is probably a little more in cost but you win in the long run as fiberglass insulation trapped in a joist bay has no way to breath.
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MtnDon
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# Posted: 18 Oct 2012 00:20
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fiberglass insulation trapped in a joist bay has no way to breath.Quoting: Anonymous fiberglass insulation trapped in a joist bay has no way to breath.
Fiberglass insulation "trapped" in wall cavities has no way to breath either.
No problems there unless something disastrous occurs; like a pipe that leaks or the exterior weather resistant barrier fails, or the door / window flashing fails, or.....
Nothing wrong will foam, and spray in closed cell foam is about the best. But fiberglass batts in a floor performs well when the bottom side of the joists is sheathed with exterior grade plywood. I have had ocassion to remove such sheathing and the insulation it covered in order to add plumbing years after the original installation. The pink stuff looked as new, was dry and perfectly serviceable for decades yet to come. Barring a disaster of course. Those don't come along often and if one does, well we'll deal with it at the time.
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trollbridge
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# Posted: 18 Oct 2012 09:45
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Quoting: swanugly i nailed plywood strips to the bottom of the floor joist before i nailed them in place . the strips were about an inch wider on each side of the joist . once the floor joist were all nailed in place i cut plywood to fit inbetween each joist , i tryed to make it fit as tight as i could .( i guess i guy could seal all the seams to make it tighter ) laid the plywood in between each joist and then added the insulation .
We did the same thing only instead of insulation batts we used the "pour and rake" stuff.
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