Is all EPS made the same? Insulation question

Factual Questions
1

I am building a little shed in my back yard. Part is going to be used for storage of small stuff like Christmas ornaments/lights, books, etc. The majority of the rest is going to be a workshop for our arts and crafts - sewing, knitting, etc will be done inside, but all the “messy stuff” - fabric dying, plastic model building, foam cutting, etc will be done in the shed where I can install a proper spray booth, a dedicated table I don’t have to cover with newspaper first :slight_smile: and the like. There will be adequate ventillation/fans for those rare occasions I’m using some volatile chemical not in the spray booth (which will be direct-vented outside).
I’m putting in a small window unit for AC (there won’t actually be a window, tho - just a cut-out large enough to hold the AC) and a sealed-oil heater for the winter. Each will be on only if needed while I am actually working in the shed.
The shed is positioned such that, with tree and house shade coverage, it only receives direct sunlight about 2 or 3 hours per day, between about 1pm and 4pm or so. I live in West Tennessee, so it’s not unusual to hit triple digits in the summer, but winter rarely gets into the single digits (tho below zero is not unheard of, it’s usually never for extended periods).

My question is in regards to insulation. I know that EPS (expanded polystyrene - not Styrofoam™, but the little pellets that are expanded and crushed together) is used as insulation sometimes - but is it all generally the same? I ask because I’m friends with a guy who owns a bunch of rental properties. He recently (well, before the bulk of the housing bust) upgraded/replaced the large appliances (and AC units in some cases) at several of his properties. Many of these were packed with 1.75" to 2" thick EPS sheets for cushioning. I have acquired these - ostensibly for building terrain and some costuming purposes - but I have so many of them I could line my shed walls with them and still have a few sheets left over.

This is just a shed, and I’m not planning to spend a lot of time out here - mostly a few hours on the weekends and the very occasional evening - so I’m not looking for uber-insulated R-297 walls, just enough to maybe help even out temperature variations somewhat. Would I be able to use these sheets, or is there a ‘special’ type of EPS, or am I better off forking over the $$ for some of the pink stuff? :slight_smile:

edited 'cause I don’t know the difference between expanded and encapsulated :smack:

2

I asked a materials Engineer I know about this. This is her response (edited for grammar but not content):

“There can be a difference in terms of stability, some types of EPS don’t weather very well and can break down in sunlight and when exposed to damp, etc. In terms of insulation there are a couple of kinds that give better R values but generally it’s all pretty good. Some types aren’t recommended for using in places where folks are living long term because they outgas some chemicals but I don’t know if you find those any more. For a shed like this guy wants if the EPS is kept out of the sun and not exposed directly to water it will probably work pretty well.”

3

Excellent. Lord knows I need to save every $$ I can these days :slight_smile:

4

My sister had a non-insulated steel garage door. About 3 years ago I helped her fill the sections with 2"EPS. It has held up well, and made the garage noticeably warmer in winter and cooler in summer…of course we insulated the walls with glass batting at the same time, so it is hard to know which had the greatest effect. Oh yeah, we have not noticed any oder.

I “glued” it to the steel and sealed joints between foam sections with latex caulk. A serrated kitchen knife seemed to be the tool of choice for cutting the stuff. I commend your chepskatedness, but you should realize that sheets of the stuff are not at all expensive…I think it cost us like $20 for enough to do a double garage door with a bit left over.

5

It’s not as much cheapskatedness (ok, so it is :stuck_out_tongue: - hey, I reuse my dryer sheets too :slight_smile: ) as it is that I have just so much of the stuff. I mean lots - I’ve got another friend that’s a cabinetmaker by trade whose shop I’ve got this stuff stashed for right now and it takes up all of one of his lofts. The bulk are sheets about 4’ x 5’ and there are almost 4 dozen of them and another dozen-and-a-half or so about 4’ x 2.5’. I’m not gonna have room to stand up unless I do something with them, and I’m reluctant to throw them out, because they are extremely useful for building terrain and the like, so I figure might as well kill two birds with one stone.

Where I’m building the shed is the location of what we figure was a single-car garage because that’s about the size of the slab that’s already there (what, you think I’m going to spend money on concrete when there’s a perfectly good slab just sitting there? :slight_smile: )