Flooring,styrofoam?

[thecfarm]

I built a Garden Shed for my wife,
https://forestryforum.com/board/index.php/topic,69197.0.html
It's about 12X24. I use one inch hemlock for the sub floor,16 on center. Really no way to get under it to insulate the floor. I do plan on putting another floor over it. Maybe Ash,maybe maple. The question I have is, can I put ½" or one inch blue styrofoam 4'X8' sheets down on the hemlock and than put the main floor on top of that? Is there something better to use? Do I need the tounge and groove stuff? Nails?

[Chuck White]

At our camp, we used R-Max (I think spelling might be off), It's about like the expanding foam you can get in a can, but with aluminum foil covering!

We used 1/2 inch!

Works nice!

[thecfarm]

I know what you mean. I've seen that stuff.

[jim blodgett]

Rigid insulation can be a little confusing. 

What most of us call "styrofoam" is known as "EPS" (Expanded Poly Styrene) in the building industry.  You'll recognise it as the same stuff we used to get coffee in, or cold drinks.  It's an effective insulator but there are serious environmental issues with it. Break a piece over your knee and you'll see little balls of poly styrene drop to the ground.  This stuff doesn't break down organically.  It gets moved around by wind and surface water, eventually finding waterways...wildlife eats it...you get the picture.

A better choice for your application would be "XPS" (Expanded Poly Styrene).  It's much tougher than EPS and would better withstand the compression issues you'll have if you place it directly under floorboards.  Plus, it's much finer grained than EPS.  When cut with a knife, handsaw or electric circular saw it produces dust, similar to sawdust.

But fair warning, the same sized sheet of the same thickness is more expensive.  Maybe 50% more at Home Depot, closer to double the price at an insulation wholesale company.

Both insulate about the same, about R-5 per inch thickness. 

As for t+g, I'm not sure why you'd need that for your application.  You might want to tape the seams and around the edges to prevent air infiltration though.  I'd go hog wild with an expanding foam like "Great Stuff" to further seal any pentrations, wide gaps or edge to wall cracks, too.  Anytime you insulate you want to stop uncontrolled airflow from from one side of that insulation to the other - that's key to getting the best insulating bang for your buck, regardless of what type insulation used.

[47sawdust]

I would suggest putting furring strips down and insulating between them,then fastening your finished floor to the furring strips.you will have more holding power and less chance that the floor might move.Fasteners will depend on your choice of floor.
I'm picturing this shed filling up with wonderful treasures if your wife is anything like mine-might not need nails.We won't talk about my wonderful treasures though.Good luck,it will be beautiful.

[woodman58]

I would use cork underlayment. You can get it up to 1/2" thick. We sometimes use it under hardwood flooring. The underlayment is very dense and does not compress very easy. Foam may have to much movement. Here is a link to where you can buy it. Or, do a search.

http://www.amcork.com/products/cork-underlayment-rolls

[farmboy1tn]

how about foil covered tar paper under your next layer of flooring would reflect the heat back up.1 inch of soild wood shoud have the same r value as half inch of foam ?

[outerbanxer]

I built a Garden Shed for my wife,
https://forestryforum.com/board/index.php/topic,69197.0.html
It's about 12X24. I use one inch hemlock for the sub floor,16 on center. Really no way to get under it to insulate the floor. I do plan on putting another floor over it. Maybe Ash,maybe maple. The question I have is, can I put ½" or one inch blue styrofoam 4'X8' sheets down on the hemlock and than put the main floor on top of that? Is there something better to use? Do I need the tounge and groove stuff? Nails?

I would use a reflective 1" rigid extruded poly sheet with the firring strip suggestion, as mentioned above. And I would also add a radiant barrier reflecting into the surface. You'll get an r-10 value plus any heater you install will reflect into the living space. Also, use great stuff to seal up any air gaps...don't let the heat settle!

[bandmiller2]

47 Sawdusty has the right idea with the spaced strips if you have the overhead don't skimp on the insulation, Maine winters are legendary. If mommy has warm feet alls well with the world. Frank C.

[thecfarm]

outerbanxer,radiant barrier? Like the foil faced tar paper or something like what farmboy1tn mentioned? Probably one inch something will be used and the strips. Yes,I will seal it all up the best I can. I use to work for the state and insulate the low incomes home. I learned how to insulate,but we could always get under the living area.
I plan on putting a heat exchanger for the OWB in there. I will put a variable speed switch on the fan to keep the noise down from the fan.I have one set up like that in the basement and really works well.
That should keep her feet warm bandmiller and her 5-6-7 friends too. I have to keep more than one women happy now. Pray for me guys.  ;D