How to Insulate a Shipping Container

[Solomon Parker]

I would like to us a used (lightly) shipping container to build a honey house. My current shop is one of those 'roofing as all surfaces' metal contraptions which is completely uninsulated. Needless to say, it gets quite warm during extracting season when I have to keep the door closed to keep the bees out. I've clocked it at 109 degrees F and 98 percent humidity. It's great for getting honey out of combs, but no fun otherwise. It's also very cold in winter when I'm working on frames and boxes, but at least it keeps the wind off.

So I'd like to have a better one which will also serve as my wood shop (building my own boxes) and a platform for a mess of solar panels. Most of all, I want to be able to take it with me when I move.

I've seen a number of methods of insulating, from the usual wood framing with fiberglass batts to fancier things like foam boards and spray foams and such. I don't like fiberglass and given space limits, it won't provide much bang for the space it takes up and I'd like it to be as efficient as possible. Another one I've seen was using Icynene, open cell foam filling in wood framing. This option looks really good, but with winters around here at least occasionally able to form ice on the inside of windows, I wouldn't want water migrating through and rusting where I can't see. Polyurethane foam would probably be the best option but it is expensive. My brother has done two with foil faced foam boards on all sides with plywood on top and they seem to work well, but how would he know if moisture were getting through?

Has anybody tried this? Any ideas?

[solarguy]

Shipping containers are a bit narrow. Nothing you can't work with, but it can affect your choice of materials.

Icynene is open cell foam, so water vapor can pass through it. You have to use a very effective vapor barrier under the drywall, but that's not that hard. Pay attention to sealing penetrations and you should be good. Shipping containers are generally made of a product called CorTen steel. It's designed to form a stable oxide layer upon exposure to the elements, i.e., stable rust.

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

Plus, they are generally painted with a good quality paint, which slows the corrosion process down further.

I wouldn't bury one, they're not engineered for that anyway, but you'd have to work at it to have any structural problems in say...30 years if you control moisture at all.

Polyurethane is r-6 per inch for the closed cell version. Only r-3.5 for the open cell spf (spray polyurethane foam). Extruded polystyrene is r-5. Icynene is "only" r-3.5 Spray polyurethane outgasses very little after the initial curing period. So basically, ventilate a lot the first 2-3 months, and then no worries. Certainly, it contains and outgasses nothing like formaldehyde like the old urea formulations. The closed cell version serves as a very effective vapor barrier. So, provided you don't get water intrusion from the outside, you should have no rust worries from migrating water vapor from the indoor activities. There are fairly straightforward ways of keeping a tightly sealed structure under slight negative pressure, which will tends to remove moisture from the insulation and framing structure, effectively drying it out and keeping it dry.

What sort of outside temperatures would you foresee? What kind of indoor temps do you need to maintain? How to heat it? Any windows?

The fiberglass bat industry has the best PR people in the world, and their product sucks like a hoover. If it get's damp, which is easy to do, the r-value drops like a rock. To attain its so-so r-values, it has to be installed perfectly and sealed perfectly, or nearly so. If it gets really cold out, like when you need r-value the most, the r-value of fiberglass plummets. Did I mention I hate fiberlglass??

All things being equal, blown in cellulose beats fiberglass in virtually every category. It can't compare to the closed cell foams for high r-value per inch though...

troy


Finest regards,

troy

[Solomon Parker]

I get temps as low as -10. It would only be heated or cooled when I'm actually in it, and I think it would be awesome to have a small wood stove, but it may just end up being a window heat pump unit.

I hate fiberglass too. Nasty stuff. I blew in cellulose in my house when I upgraded my ceiling. Also gets rid of mouse problems.

[Ian]

just an idea,
instead of putting alot of money into insulating a shipping container, why not buy a reefer van and use it the same way. They are insulated and most all have a good washable floor in them

I use an old sea can for surplus storage space added onto my honey house. Worked well at the time but as you mention, it heats and cools too easily
I have often thought about replacing

[Solomon Parker]

I have thought about buying a refrigerated container, but it would cost more than just insulating it myself.

[Ian]

Here there is a row of them for $5000, by the time you buy 53' worth rigid board insulation and then a sealed covering your likely going to spend more than that

[gmcharlie]

http://www.energyefficientsolutions....Spray-Foam.asp

I did 3 15 X 8 walls 4" thick in about an hour with one kit......air and moisture tight. perfect for steel as it keeps condesnsation off. My whole 4000 sqyare foot shop is done, but we only did the office DIY...

[solarguy]

If you do the biggest do-it-yourself kit of 2 part polyurethane closed cell spray foam, that works out to $12 per cubic foot of installed foam, assuming you do a perfect job and it's the perfect temperature, and you have the perfect amount in the kit to do your job.

http://www.energyefficientsolutions....Spray-Foam.asp

So, since those are all pretty unlikely, your installed cost will be higher than $12 per cubic foot. A pro that does it for you may or may not beat that price.

High density extruded polystyrene (blue board) has nearly the same r-value per inch, at a cost of just under $5 per cubic foot, and there is not much waste and you can buy as much as you want. Installation is more fiddly and time consuming, but a lot cheaper for the same r-value. You also need to install a separate vapor barrier or tape the seams and foam the edges.

White Beadboard (expanded polystyrene- looks like little beads molded together) is cheaper, but has much less r-value per inch so it is a false economy.

You pay your money and you takes your chances...

troy

[Solomon Parker]

Troy, I was down at Lowe's this morning looking at the polystyrene and I had an idea. I use the polystyrene as an outer layer, glued to the inside walls. Inside that, I frame with regular 2x4's, install wiring etc. The question then is with what to fill the spaces between studs. Maybe Icynene, it seems I could have it sprayed for relatively cheaply. What do you think?

[solarguy]

At some point, you should do some basic heat loss calculations. Until you do that, you don't really know how much insulation you need to make heating and/or cooling possible, affordable and stewardly. Maybe 2" of hd styrofoam is overkill. Maybe 6" of styrofoam is not enough. In either of those scenarios, adding icynene is inappropriate.

It's less complicated than balancing a check book. This guy does a nice job of unpacking the process if you are unfamiliar with it:

http://www.greenbuildingadvisor.com/...ulation-part-1

There are a couple parts, but you'll get the gist of it in 15 minutes. u-factors are the inverse of r-values. r5 = 0.2 u-factor. A little work with a spreadsheet and you'll have a place to hang your hat and make decisions about insulation values.

What are you going to heat with? How much insulation you have (and the temperature delta, of course) will determine how big of a wood stove or heater you need.

From a general principles view point, there is nothing wrong with your plan to put icynene over polystyrene, provided you get sufficient r-values. Wood is a pretty crappy insulator (r-1 per inch on a good day) so it's helpful to put studs on a 24" centers, or use 2x3's, so long as they are not holding up the roof.

hth,

troy

[gmcharlie]

Your missing a part of the point. instalation is critiacal. since shipping containers are not smooth you will have air space this space will condense moisture no way around it. Spray foam solves that problem. the other part is I am not sure where your math comes from. both Handi foam and tiger foam (which I used) sell a 600 BF kit for around 600$ thats 1.00 a bf in my math

[gmcharlie]

hh I see your calculating cubic feet not BF......My opps...

[Solomon Parker]

This is not a conditioned living space, it's a shop that will be heated and cooled about two weeks out of the year. It WILL have a beyond oversized heating and cooling system. It will be better insulated than my house. These things are very easy to do. My concern is condensation.

In the summer, any moisture is going to be baked out by the sun on the metal.

[Solomon Parker]

I did some heating calculations. With what I consider minimum insulation levels, I'm looking 4300 Btu heating and 3000 Btu cooling. I also found a 9000 BTU minisplit system which would be really sweet. Having no windows and only one door makes calculations a bit quicker.

[solarguy]

" you will have air space this space will condense moisture no way around it."

That all depends on a number of factors. There is air space and air movement between the two panes of glass in a thermopane window. If the window is working correctly, there will never be condensation.

But your point is well taken. A closed cell foam, sprayed on an irregular surface, is a good way to minimize condensation due to humid interior air getting to the cold outer surface. Even that is not a guarantee though. If you have any moisture intrusion from the outside, it is now trapped against the metal with no way to get out through the closed cell foam.

Sol, it is temping to go oversized, but resist the urge. In the summer, an oversized AC unit will drop the temperature quickly, but remove hardly any of the humidity, leaving you cool, but clammy from the humidity. Any heating unit that burns a fuel will also not like short cycles which will make it/them less efficient. Resistance electric heat won't care, but heat pump will run less efficiently with short cycles. In round figures, you basically could not find a wood stove small enough to provide 5,000 BTU's per hour. You could surround the stove with water to soak up the extra heat to be released later and only need a couple short hot fires a day. Insulation is magic.

troy

[Solomon Parker]

I don't believe in magic. Don't believe in luck either.

I guess a heat pump it is. However, it seems hard to find any minisplits under 9000 BTUs. That is just the maximum however, and most of them have multiple speeds. Not on/off like a regular air handler.

http://greenfirefarms.com/2012/02/th...r-barn-part-9/ Check this out. Part 13 is the finished product.

[Gord]

Look up "Reflectix" insulation, or similar.

Look for the generic stuff; up here, I can get double layer 4' wide x 125' for $225.
Thin, critters don't like it, huge insulation value for 1/4" of thickness.
I put it under a metal roof, and can now heat and air condition my cottage; previously, the roof made it impossible.
Really good for reflecting radiant heat.
These folks carry a similar product.
http://www.insulation4less.com/Insul...BestDeals.aspx

[Ian]

thats the stuff I use under my hive covers. Good stuff

[gmcharlie]

solomon, how did you calculate the heat load from the bees? thats been vexing me for 2 years....

Actually I was looking at the refers for walk in coolers. they are pretty cheap and small as well as you could stack units real easy

[Solomon Parker]

Heat load from the bees?