Shop insulation, Southern California

I am planning to build a small hobby shop near San Diego. I am inclined toward a metal building but conventional framing is possible. Comments regarding insulation, ventilation and skylights in this sunny, temperate environment would be welcome.

Ruperto, I suspect you will get some good ideas here but also suggest checking out the garage journal forums as there are 1000s of posts on garage and shop construction there as well. A bunch of the members here also spend time there.

So the garage journal will probably not help you so much with ventilation because you have a dust issue. Is it temperate enough that you can bring in unheated and unconditioned air? if so you will not need a HEPA filter on your dust collector, you can just vent it outside and open a window for replacement air. Similar question for fume management when finishing.

If you want humidity control you may need air conditioning.

In your location, I would build a metal building so you will not have to repaint as much as you would wooden siding. Insulation may be a good idea but just for noise control. Put your dust collector in a separate shed. (that is what I have) An exhaust fan of some kind is a good idea and a ceiling mounted air cleaner is also a good idea. The weather, where you are, is so mild that ventilation is about all you will need for temperature control.

Multi-generational SoCal boy here so this is my home turf. San Diego is mild even by California standards. Weather is not something we deal with, we visit it and then go home when we're done. That being said, your proximity to the coast will make a big difference in what is important to you insulation-wise. Otay Ranch, National City and La Mesa all have very different micro-climates.

If you are 25 miles from the coast, some ceiling insulation will probably do you. If you are 5 miles from the coast, I would do walls and ceilings. Metal or Wood construction won't matter. A really good paint job can last 20 years in SoCal. 25 miles from the coast and you would almost have to try to get rust on your bare metal surfaces. 5 miles from the coast and your dew point comes more into consideration.

I'm north and east of you in the general area of the Morongo desert basin. Coastal changes are only mildly noticed this far inland. dad is in your neck of the woods about 6 miles from the Pacific. He has to be aware of moisture and the salt air does strange things to some plastics.

Ruperto, my workshop is maybe 12 miles from the coast, south of downtown Los Angeles, so hotter than where you are. The ceiling is uninsulated and it absolutely bakes inside during the hot months. It was up to 32* last week in the afternoons.
My buddy's workshop two doors down (same complex, same building) has an insulated ceiling and it's a very comfortable working temperature even in the dog days of August and September.

As you own your shop I would think about insulating the ceiling / roof for heat, and the walls to keep the peace with your neighbors.

Openable skylights would be very handy to have, I think.

Your shop will be unbearably warm in the summer months if you don't find a way to keep it cool.

I live in Orange County, and my shop is a 3-car garage. I blew insulation in the walls and ceiling, and installed a mini-split HVAC. I also installed one of those insulation kits on my garage doors (although I'll upgrade the garage doors to something better insulated next year.) The shop stays more comfortable than my living room. ;) Comfort is, I think, the most significant factor that determines how much time you'll spend in your shop.

I live in central Calif valley and before I insulated a couple of walls, it was down in the low 40s in winter, now with insulation only, stays in mid 50s in winter with out using heater (well pilot light and water heater). I have a smaller 12k btu gas heater and swamp cooler for summer dog days. Swamp cooler helps blow all "non caught" dust out front of garage. Randy

Doesn't matter where you live, insulation is important if you want to keep the temperature gradient in your shop/garage at a minimum. In other words, you want the temperature swing in your shop to be as little as possible and insulation is the key to that. As to what kind of insulation, I really like foam insulation and if your place is small enough, a DIY kit (google 'foam it green'...I've used them twice now...good stuff) might be the ticket to save money...maybe.

As to ventilation, if your shop is small enough, a portable A/C or heater might be enough to keep the environment comfortable for you.

Lighting is your call on how many windows/skylight you want for natural light versus T8 fluorescent or LED.

I just realized I wrote that it was "up to 32* last week" in my workshop, but forgot to write "celsius". The post cannot now be edited.

I grew up with celsius and sometimes unconsciously use that scale of measurement. 32* fahrenheit, as it probably read to most forum readers, would be an interesting occurrence in Los Angeles.

I also live in the San Diego area (North County). The biggest problem that I ran into was the building permit process. That took several months. I was also forced to add fire sprinklers to the building and non-flamiable siding by the local fire department which added considerably to the cost. The building had to pass their inspection as well as the building department's inspection before I could move anything into it.

Before you do anything may I suggest that you find out what the requirements are in your area for outbuildings. Especially here in San Diego they may be considerable and strange. i.e. in some areas you can only have a certain maximum percentage of roof square footage on your lot, buildings like the metal one you are looking at may not be allowed, skylights must be at least a certain distance from the property line., etc. You also need to understand that unless you bought the home within the last two years that the value of the building will be added to your California property tax.

I had Tuff Shed build me a workshop/garage a few years back. It was cheaper than a "stick built" building of the same size. The foundation, electrical, insulation and drywall were done by a contractor. I had planned to hold off on the insulation and drywall but the fire department gave me two choices on the sprinklers 1) copper pipe and no drywall 2) plastic pipe behind drywall. Since I was eventually going to add the insulation and drywall I chose the second option. The building really fits my needs and matches our house very well.

Answers to your questions: R-13 insulation was the highest that would fit in the walls of my shop/garage and above the ceiling I went with R-30. The garage door is insulated as well. You can Google charts that will give the recommended insulation values. While originally I had designed the building with skylights I discovered that it was too close to the property them (some kind of fire danger requirement). I had three large windows installed in one wall instead and love them (All windows had to meet a specific code requirement as well.) On nice days the windows really add to the ventilation when I open them. My current plans include adding a mini-split heating/AC unit. Even with the insulation the building is pretty cold in the winter and gets very hot in the summer. While a small electric heater helps in the winter the summers, especially last year, can be way too hot for me to be comfortable. I hate sweating on finish that's just been applied or on that newly sanded furniture piece.

I live 20 miles north of San Diego and about 15 miles inland. I wanted my workshop to be compatible with my house and neighborhood, so I built it in the same style as my house.

My workshop is a 2x4 wooden stud construction on a slab - - 24 x 36'. The wall exteriors are stucco (essentially no maintenance), the roof is concrete tile and I have two skylights. The skylights were inexpensive to put in initially and add a lot of light. I insulated the 3-1/2 " walls with fiberglass and put 5-1/2" in the ceiling. I put in 60A @ 220 volts, and sprinkled a quad outlets about every 6' (a bit of an overkill, but doing at that time, it was cheap to do). I also put in a pair of overhead ceiling fans (this is also a very good idea and worth the $ and effort). I also plumbed in compressed air lines. I also put in a whole house fan. Then I covered the interior with 1/2" drywall. As an afterthought, I added to small window ACs at each end. They aren't adequate to really cool the shop down when it gets in the upper 90's or more. But if I plan on working on a really hot day and turn the AC units on in the early morning, it will maintain the early morning temperature.

A friend talked me into the insulation. At the time I doubted my friend's advice and thought that it was overkill. But it was cheap and easy to install when I was at that phase of construction. Now I am thankful that I followed my friend's advance. In the winter it keeps the shop pretty comfortable and in the summer it helps too. If you live on the coast, perhaps it wouldn't be as noticably helpful, but if you live inland, you'll appreciate it. Maybe not today or tomorrow, but some day you'll be thankful that you did it.

I have few regrets in what I did, but the most significant one is perhaps that I didn't make the shop bigger and/or consider adding a second floor.

Another approach that isn't as pretty or an asset to your property: If you wanted to go really cheaply, have you considered picking up two or three 20, 30 or 40-foot cargo containers. I think that you can get them delivered on site for around $2500. If you use some creativity in arranging and connecting them you could end up with a nice work space. Check zoning before you go too far though.

Let us know what you finally decide.

For some reason it is hard to find but R15 insulation, is 15% more insulation for almost no increase in price. I do not understand why California allows R13 2x4 walls when R15 is available?
Bill

If you insulate without drywall you do not have much choice due to fire code. Rock wool is about the only choice, luckily it is higher r value then fiberglass. Roxul is only brand I know of. Ther e may be some spray foam that has fire resistance but check with building department to see what is allowed and how to prove it.