Shop Heating: Insulation (Long, but worth it!
Brad Vietje
Just so I don't completely hijack John's shop heating thread, I figured I start a different one on insulation. I would caution anyone in John's situation to consider insulation options just as thoroughly as your heating and/or cooling options.
What do I know?: Some of you know that I design and install solar and renewable energy equipment, but in truth, the most important work I do is to help people explore options to be more efficient, more comfortable, and to save money, regardless of whether they ever use any solar products. I've worked for the past 7 years on an engineering and design team to help our clients create Zero Energy Buildings, and in the end, insulation and air sealing is far more important than the energy source. On this theme, if you're building a new structure, and you can find a way to spend 10% more -- putting it into the thermal performance of the building -- it will save you 70% on heating and cooling for life. Swapping an older heat plant for a high-efficiency unit will usually save you only 10-15% of that.
Here's the deal -- you only have access to really tear into those walls once, and getting the insulation right will not only keep you warmer in winter, but also cooler in summer, and can save -- or cost -- you money for as long as you own the building. To retrofit a shop after all that equipment and storage is in place it is just too difficult, so most people don't do it. It's usually a lot easier to swap heating systems than the insulation and wall/ceiling/roof structure, but no where near as effective. Getting the insulation right is a much better investment, in other words.
I work in northern New England, so while I know quite a bit about our local needs, I may know nothing about your local conditions. However, physics is still physics, and aside from differences in vapor barriers and such, we're still trying to resist the movement of heat from place to place. Below are some of my thoughts, and I realize that YMMV, and there is of course, no requirement to agree with me -- I'm just trying to save you some $$$ 
Brad's Insulation Rule of Thumb #1: More is better. Properly installed insulation*** resists the movement of energy from warmer places to cooler places. Insulation helps keep you warm in winter and cool in summer.
Brad's Insulation R.O.T. #2: Building codes are very low standards. If your local code requires X, think about 2X or 3X.
Brad's Insulation R.O.T. #3: All the insulation in the world will do you no good if air (or, Heaven forbid, water) can move through the structure. Insulation w/out proper air sealing is wasted money.
Brad's Insulation R.O.T. #4: *** Insulation is rarely installed properly! Many, many contractors do such a lousy job of installing insulation that they should be fined, and put out of business, though that almost never happens. This includes fiberglass, cellulose, foam, you name it. If you hire someone, hire someone good. If you do the work, be sure to do it right.
Brad's Insulation R.O.T. #5: Fiberglass is not insulation. Good rodent bedding, and a great place to find snake skins, thousands of ladybugs, mouse turds, and other dead things, but really poor insulation. Why? Because air moves through it, lowering it's effectiveness (a lot). Better horizontal than vertical, and only when backed. If you have any choice in the matter, use something else. Applies to both batts and blown pink crap. Trust me - use something else.
Best insulation? Difficult question, since they have different properties. Thoughts:
Spray Foam: (closed cell Isocyanurate foam)
Plus: Highest R-value per inch (R 6-7 per inch), adds structural integrity and great moisture barrier. Good sound attenuation (keeps noise out).
Minus: often the most expensive option, and stops moisture dead in its tracks -- which can cause huge problems if that's not a good place for moisture, or has not been carefully thought out.
Other: sometimes the only way to get desired level of performance out of a fixed wall thickness. Made from petroleum. MUST be treated with fire retardant if exposed, and creates highly toxic fumes in a fire. R-value will go down as it cures, or out-gasses (and you don't want to breathe what it releases).
Open Cell Foam: can absorb and trap water, shrinks and settles over time: not recommended.
Dense-Pack Cellulose:
Plus: 1/3 to 1/2 the cost of spray foam for a given R-value; environmentally friendly and relatively non-toxic -- made from ground up recycled newspaper; highly fire retardant, since air can't move through it; treated with Borate to keep bugs and mice out. R value of 3.8 per inch when properly installed. Excellent sound attenuation. Very good air sealing if installed at high density & pressure (5.5#/sq. in.)
Minus: requires thicker walls to reach higher R-values; can be very messy & dusty to install. Requires screws and often temporary strapping to keep drywall or other sheet products in place during install (5.5 #/in = almost 800 #/ft sq, and a tremendous force over a 4' x 8' sheet!
'Nuther option is Damp-Spray Cellulose, which performs just like dense pack cellulose after it dries out fully (usually 1-6 weeks); can be spray-applied to open bays between framing; good air sealing when properly installed. A LOT of fun to install with the right equipment!
Lofted (Loose) Cellulose:
Plus: Good for attics if no access is needed; best if attic can be stuffed full; inexpensive; can be owner-installed; about R 3 per inch, but only when used above a solid surface or membrane, or installed at minimum depth of 12" to reduce air movement (not an issue for dense-pack cellulose)
Minus: very messy and dusty; poor choice where attic access is required. Not good for walls -- settles unacceptably and does not stop air flow (see fiberglass).
Sheet Foam Products:
Plus: Great for retrofit work; fairly rigid & strong; needs to be sealed between sheets; easy for homeowner work; easy to transport, cut, etc... R-value varies from iso-cyanurate foam (R 6.7/ inch +/-) to styrofoam and polystyrene products (R 5.5/"). Foil-faced iso-cyanurate foam should be used when insulation will face an air space.
Minus: foam is made from oil, and tends to end up floating in the ocean; not biodegradeable; needs to be taped and sealed for best effect.
Fiberglass: only mentioned here out of spite. In a wall cavity, warm air migrates up the warm, inner side, while cold air moves down the cooler, outer wall, creating a heat pump circulation that helps move hot to cold. Fair when used flat in an attic as long as foil or paper backed. Almost never installed correctly, as every interface, pipe, wire, switch, or receptacle box needs to be carefully sealed. "R-19" fiberglass in a wall cavity tends to actually perform at about R-11. Poor choice.
What to do? Depends on budget and other factors. In my location, what I would do is rip out whatever is there, use Larsen truss system* to build out the walls to be 10 - 12" thick (extending window & door framing to accommodate), and have the walls stuffed with dense-pack cellulose. 10" = a true R-38 if properly installed, and 12" = R 45. For roof/ceiling, it depends on the structure and the roof composition, but getting at least R-50 up there is a good idea -- and I mean true R-50 performance, not 2 layers of fiberglass batts. I'd also consult a local builder or even better - a trained Igloo or NuWool cellulose installer to get advice on moisture management for your local
climate.
* Larsen trusses are built with 2x3's attached to the current framing with 3" wide tabs of 1/2" plywood -- a very inexpensive way to build a thick, high-performance wall with almost no thermal bridging.
Here's MY house last Friday afternoon at 2 degrees F: Straw bale walls are about 17" thick, 17.5" of dense pack cellulose in roof structure -- note NO icicles 
8000+ heating degree days, but only 2 cords of wood to heat -- the little wood box outside the door provides 2 months of heat when stuffed full of dry wood. No cooling needed.
Waay too much info, but hopefully helpful....
Safe spinning,
Brad Vietje
Newbury, VT
