Cheap insulation. Is there such a thing?

AlV said
Cat on a hot tin roof.

Good morning Trip... That's an interesting question.
I presume that your shop gets direct sun most if not all of the day essentially making it a hot box. What we have here is a cool Hand Luke scenario (sorry).

My first thought is shade, if you could provide shade to keep the sun off of your shop that would be a huge step. If shade is not an option. I would recommend installing an exhaust fan and fresh air vents to draw air through the shop which could help keep the heat from staying trapped inside the shop.

Insulation is also a good idea but keep in mind that it works both way (keeping temp out and in). I suppose you could go to the local DIY warehouse store to pick insulation up there. Some things I would consider:

* if the garage is dry you can go with either roll or panel.
* if the garage is wet I would stay away from roll because it could trap water.

I believe that one thing will marginally improve the situation alone. But a combination of air circulation and insulation will yield improved result. Better result will come from insulation combined with AC. Best result come from a combination of shade, insulation and AC.

I know that this info isn't an earth shattering revelation. It's just food for thought.

Take care.

AlV

X2 the above...that's what I found when I built my shop. The only thing I'd add is consider a spray on heat block as part the the "shade"...do your research and pick one that blocks at least 80% of the radiant heat...I used STSCoatings. not flammable and won't smoke. You can brush, roller, or spray it on. The temp will still be the same as outside, but it will be like standing in the shade...add airflow and it's like being in the shade with the wind blowing. It gets really hot here in Tx and I can work in my metal shop even when it's over 100. I'm not in there everyday though. Best is heat block, small airspace layer, insulation, drywall, air conditioning...especially if you'll be working in there every day. On a tight budget like I was on the heat block has been great. Blocking that radiant heat is key to keeping all the metal inside your shop heating up that then heating you up. You can spot spray roof hot spots to save $$ too...say a tree provides 1/4 shade...well, you get the idea. I checked Internet auction sites and found panelling to do most of my shop for $5. Tax collector bought the old Sears building and wanted the panelling gone...sad when the tax office is expanding and business's are leaving!