Little Cabin in the woods...that could use some insulation

[Wingman]

Borrow from the stove thread...https://www.hearth.com/talk/threads/little-cabin-in-the-woods.131086/

My dad finally bought his "little cabin in the woods." Its an A-frame that basically sits on a cliff overlooking a beautiful farmland valley. Right now it has three kinds of heating units, Olympia wood stove, a Warm Morning Propane heater and an electric 220v heater. With a virtually endless supply of firewood possible and myself using an 13-nci, he decided to go with a new, more efficient Englander stove and put the old one out to pasture.

The cabin is about 1300 sq. ft. set up in a T shape (if you looked at from above) and is basically two rooms, a bathroom and everything else. The kitchen, bedroom, living room and mezzanine are all an open floor plan.

We know there is insulation in the roof/walls but there seems to be no insulation underneath the flooring. The way the cabin sits, it is on piers on a virtual cliff that always has a breeze. Would it be feasible to insulate and or seal the floor joist from underneath to help keep the wind from blowing through and infiltrating the cabin?
Right now somebody is going down there every week and half but I expect that to pick up once the leaves start changing.

 

[Jags]

Closed cell spray foam???

 

[woodgeek]

Open cell would be cheaper, and likely work just as well. Worried about animals getting into it? Could tack 'hardware cloth' under the joists, and fire the foam through it.

 

[Jags]

I would be more concerned with harboring moisture.

 

[woodgeek]

I was figuring a cabin would be (1) not air-conditioned, so no Humidity on the cool side problem in summer, and (2) drafty enough in the winter to be low humidity (esp if only used part time) so no humidity problem on the cold side (i.e. joists) in the winter either.

With no vapor barrier or sheathing on the outer side, it would be a vapor permeable air barrier.

Not like its a cold attic with warm humid air pouring from below all the time.

 

[Jags]

Hmmm...maybe. My cabin gets cooled in the summer and heated in the winter, so I was taking it from that prospective. Well that and I am right on water (humid environment).

 

[semipro]

You could also install sheeting on the bottom of floor joists and then fill the cavities with packed cellulose insulation. If you want to avoid thermal bridging across the joists foam board can be installed just above the sheeting. Soffit board would work well.

 

[woodgeek]

Yeah. Nice idea. A decent person who knows how to properly do densepack cellulose could prob do it cheapest....and the cellulose provides decent airsealing by itself. I would use vapor permeable but not air permeable sheetgoods underneath. Maybe EPS or thin XPS stapled up??

 

[Dune]

Spray foam provides the best protection against cold air infiltration

 

[Seasoned Oak]

I have found that those small propane heater while providing quick heat,are very expensive to operate. THe problem lies in the cost of filling those small tanks. Paying $4 -$6 a gallon for propane can make them double the cost of electric resistance which is by the way the most expensive form of electric heat. Use the wood stove as much as you can.

 

[maple1]

Whatever you do don't install fiberglass. Rodents absolutely love finding that stuff in the woods. Buddy tore all the fiberglass out of his (it was a huge stinky mousey mess), and just put a tight layer of OSB on the inside. The air sandwich seemed to insulate fairly good, and his wood stove keeps it lots warm. It is just a camp in the woods, but it's a nice spot to spend a bit of time.