Design and Construction - Building the Ultimate Garage
****This webpage was created in 1996. Building products have improved but many of the basic design & construction recommendations are still valid today.****
To most homeowners, the garage is merely a space to park a car or two (if you're lucky) and a repository for an eclectic mix of lawn furniture, toys, half-finished projects, and other "stuff" that, in my eyes, really doesn't belong here. A growing part of my business is the Design, Construction and Setup of residential and commercial garages and workshops. Ideally, I like to work with the architect and client at the planning stage of any new construction or remodeling project and I offer below a brief series of considerations for the homeowner on building the Ultimate Garage.
The key factors to consider in the design are ergonomics, aesthetics and safety. It's best (and required by local construction code) to hire an architect or engineer to help with the design. A new garage can be "attached" to your existing home which is generally the case or "detached" as a separate structure if you have enough property. There are advantages to each. Try to keep with the existing architecture of the house. Remember, you may have to sell your home someday and your garage/workshop shouldn't be an eyesore or hindrance to this sale.
TYPES OF STRUCTURES - "Attached Garage"- This is generally cheaper to construct as you already have an existing wall to work with and your utilities (heat, electric, and water) are easier to access. You will be required to use fire code sheet rock between the garage and the living area as well as a fireproof door.
"Detached Garage" - I prefer a detached garage for safety and security reasons. A fire in a detached garage is less likely to spread to the house and someone breaking into your garage cannot gain direct access to your home. You can also use the structure to block the view from your neighbors of the ongoing activities in your workshop. Secondary buildings don't have to adhere to the same setbacks as primary structures. My personal garage is set 10' from the property line and yields much more privacy than a fence or row of hedges.
SIZE - The ideal size for a one car garage/workshop is about 20' wide by about 25' deep. This should be engineered as an unobstructed floor area (i.e. no lally columns or posts) through the use of laminated wood or steel beams. The ideal height is approx. 15'. Many towns use 15' as the maximum height for a secondary structure for tax assessment purposes (i.e., over 15' would be a primary structure and would be taxed at a higher rate). This is a consideration when building a detached workspace. As the ultimate garage/workshop would have a parking or service lift, you'll need to consider ceiling height and roof pitch when determining the work area (vs. storage area). If you don't plan on having a lift, you can frame an 8' ceiling height and use the attic space for additional storage.....or you can use the loft area for an office or guest area.
{Note...the discussion below will focus on the workshop area. You can build a multiple car garage for storage purposes but generally one of the bays will be a dedicated work area}
BASIC CONSTRUCTION - Outside walls should be of 2x6's to allow the use of 5" (R19/R21) insulation. This is especially important for a detached garage which will be more expensive to heat in the winter. Roof framing should be 2x10's (R25/R30 insulation) for load purposes although 2x8's would be OK on a small structure. There might be 1 or 2 large beams (steel or laminated) to avoid support posts and columns in the work area. The floor should be 5" concrete (4000psi with fiberglass mesh and rebar). You should be able to avoid the use of expansion joints in a 20x25' area. Make sure you've got a slight pitch on the floor towards the garage door opening to avoid large puddles from melting snow or when washing your car inside. The foundation (poured or block) should be at least 18" off the floor, again to prevent water damage to interior walls.
DOORS & WINDOWS - The single entry garage door should be at least 8' wide by 6.5' high (9' wide by 7-7.5' is ideal) and a quality steel or other insulated door is preferred. For two car garages, consider a single 16' garage door with proper reinforcements to prevent bowing in the up position. I frequently specify custom high lift tracking with torsion springs (vs extension springs) to maximize the usable headroom in the garages I design. If your ceiling height is only 9-10' (instead of 12-14'), consider going with a 32" radius track to maximize headroom and trunk/hatch lid clearance (when fully open). Polyurethane rollers can be used to quiet the travel of the door in its tracks.
Windows and skylights should allow for cross ventilation during summer months or for venting fumes and exhaust. I like skylights as they allow for natural light without taking away precious wall space. A venting skylight (such as a Velux, Anderson or Pella) is preferred but make sure you've got enough roof pitch (4:12 or better) or leaks will eventually occur. I like Pella casement windows as they allow for blinds to be installed between the inner and outer pains of glass (cleaning and maintenance is much easier). Windows should be framed at least 48" off the floor as this allows for workbench/countertop installations along the walls below the window(s). A detached garage should have an access door in addition to the main garage door. This door should be 36" wide and should open out for security reasons (it's much harder for a burglar to kick in an out swinging door).
UTILITIES - There are 3 basic utilities, the most important being electric. A garage/workshop should have at least 40 amps with its own 10 circuit sub panel. A garage with electric heat will need 60-100 amps depending on size. Water is important for cleanup (and car washing) but does not necessarily have to be in the workshop area. Natural gas access will make heating the area much less expensive (than electric heat). "Compressed Air" should be thought of as the 4th utility (its actually # 2 behind electric in industry today). It is used to run a variety of air ratchets, hammers, drills, sanders, etc. as well as to blow clean/dry parts and fill tires. There should be several air outlets (disconnects) located around the workshop to avoid dragging hoses across cars. Think about where you're going to locate your compressor and run 1/2" galvanized (remember there's moisture in compressed air) piping from this area to your outlets. This plumbing should be done before the sheet rock stage. I've seen shops use copper piping (type L is harder) for their air lines and high burst strength "hose" can be used as an option (never use this behind the drywall). The best (and most expensive) piping is 316 stainless steel which I've used for several commercial installations. Available in 20' lengths, your plumber will need special dies for his pipe threading equipment when working with stainless. (Update 2024 - battery powered tools have come a long way and I no longer see the need for big compressors or air distribution systems in home garages & workshops. A smaller compressor to fill tires and run the occasional nail gun is adequate these days.)
DRYWALL & WALL COVERING - As mentioned earlier, if the workshop is attached to the house, you'll probably have to use 5/8" fire code sheet rock. For a detached garage, check with you're local building department. The walls should be painted a light color to reflect light. I've seen vinyl wall coverings in garages which is easy to clean. My preference is to glue 4x8' sheets of Fiberglass Reinforced Polyester (F/R/P) over the sheet rock (there's no need to tape/spackle the joints where this is being installed). FRP panels should be ordered in 1/8" thickness and are durable enough to take a hammer blow without denting. They are available in a multiple of colors and finishes with sizes up to 5x10' and most manufacturers offer the appropriate trim and joint moldings to do an aesthetically pleasing installation. I like to use color inlays and borders to break of the monotony of large solid color walls although the mounting of memorabilia and artwork can be just as effective.
FLOOR TREATMENT- If you've got a newly poured floor, don't do anything for at least 30 days (it takes a while for concrete to totally cure). Most people will just leave the floor a natural light grey. In my opinion, this is better than painting it with a regular masonry paint which will tend to light and peel when a hot rubber tire rolls or turns on the surface. In addition, basic paints will not hold up to many basic automotive fluids (oil and brake fluids). The cheapest way to dress up the garage floor is with an industrial floor paint, generally an epoxy or urethane system. Benjamin Moore sells a line of industrial paints which should hold up fine for most light duty traffic and exposure. However, for heavy mechanical and chemical abuse, these systems (which are only 4-15 mils thick) can start deteriorating within 2 years. Oil, brake fluid and water can leach under the surface and accelerate the floors destruction. Other options include rubber tiles (Pirelli and Armstrong are popular) which come in 12x12" squares and are easy to install. They also come in a variety of colors. The problem here is that they don't make a very good shop floor. Rolling a jack or a tool box is difficult and the tiles tend to discolor with chemical exposure. I've also seen quarry tile installations on commercial jobs (BMW uses them at their educational facilities here in NJ). The problem with quarry tiles is keeping the grout joints from staining. If you decide to use ceramic or quarry tile, stick with a small size (6"x6") as these are less likely to crack. The tile solutions, rubber and quarry tiles, are on the expensive size, $5-12 per square foot installed.
The floor I prefer for most commercial installations is an epoxy/quartz based system (check with the industrial flooring installers in your local yellow pages). This solution is used by many auto dealerships and fire departments. If this surface will hold up to the abuse of a 66,000 lb. fire truck, it should last a lifetime in your home garage. Overall thickness of the finished application is 1/8" (125 mil) with a textured surface to prevent slipping. A wide range of colors are available and multiple colors are popular on many projects. You can even seal your favorite logo (like a 48" BMW roundel or Porsche crest) below a clear coat on the surface of the floor. Installed price for this product (the prep is very labor intensive) runs $4-6 per square foot.
HVAC (heating/ventilation/air conditioning) - Garage heating should have an adequate fan to move the heated air throughout the work area. There are several good forced air electric and gas heaters or you can run a separate zone off your existing home heating system if the garage is attached to the house. Gas will be much cheaper to run, but make sure any gas fired heaters are vented from the outside (you don't want to use the oxygen from inside the garage for combustion). For garages with high ceilings, nothing beats a paddle type ceiling fan for moving air (typically 10,000cfm or greater @ 70w/hr), especially all the heated air that collects at the peak. I have a 48" commercial ceiling fan on a speed control with a line voltage thermostat for the fan circuit to turn it on and off at set temperatures. I've also got a cupola over the storage garages with a 1350cfm thermostatically controlled fan to keep the storage attic from getting too hot. As mentioned earlier, its a good idea to have cross flow ventilation between windows and/or skylights (make sure you've got screens to keep the insects out). If you live in a warm climate, a wall mounted A/C unit is a good idea (such as a Sanyo split system unit with infrared remote to control the temp settings). (Update 2024 - minisplit heat pumps today are very effective at heating and cooling. Good to below 0 degree temps. My Mitsubishi and Fujitsu units heat and cool my home and garage all year. Still a good idea to have a gas heating system if you live in a colder part of the country or want (heat) backup in the event of a power outage.)
LIGHTING & ELECTRIC - Besides the natural light through the windows and skylights, there should be ample general and task lighting. Pairs of 48" fluorescents are great for general lighting and can be recessed with wrap-around covers to give a nice clean look. Task lighting above the workbench areas should be "halogen" (you may have to frame soffits to house the recessed task lighting). Lighting from halogens is much more natural (whiter) than the yellow light given off by the standard A or R type tungsten bulbs. All lighting should be on dedicated circuits-you don't want to be using an electric saw or grinding wheel and have the lights go out unexpectedly. Make sure you've got plenty of 110v, 20 amp outlets, some on dedicated circuits (run 12/2 or 12/3 cable for all of your 110v circuits). Outlet location should be planned in conjunction with your cabinetry and countertop layout. There should also be two 220v circuits, one for a compressor or lift and a second by the door for outdoor use (run 10/3 cable for circuits up to 30amps). It is doubtful you'd ever need anything higher than 30amp in a residential setup unless you've got an aqueous parts cleaner or a large arc welder. Outlets near the doors will have to be GFCI protected (some inspectors may insist on GFCI protected circuits throughout). Decora style switches and outlets make a nice touch (make sure you purchase "commercial grade") and isolated ground circuits should be considered if you've got a lot of expensive/delicate test equipment. Before the walls are closed up, you might also think about running speaker wire (CL3 rated, 16 gauge or better, 2 or 4 conductor) for architectural in wall-speakers (ear level is preferable over ceiling mounted-I like Boston Acoustics and Triad brands). Run telephone lines (if you plan on having a modem in the garage or don't want to use a portable phone) and RG6 coax for video/TV use. (Update - in 2002, I started running wall drops off the subpanels for EVSE feeds (ie, power for electric car wall chargers). This should be standard practice these days. A 60amp circuit is ideal as it allows 48amp charging, the most any EV's will currently accept on 240v. Also, most garage outlets now need to have both Arc Fault and GFCI protection along with being Tamper Resistant.)
[Note: if you're trenching from the house to a detached garage, your power feed (use #1 copper which can carry up to 150amps) should be in its own Schedule 80 conduit. You should run at least 2 RG6 coax lines (1 for compressed audio as such as Sony DST, 1 for video), 2 phone lines (1 voice, 1 data) and a few 18/2 twisted pairs (for IR. repeaters and other data transmission). These cables should be in a separate Schedule 40 conduit. For you folks already using an IEEE 1394/Firewire interface in the house or office, consider running fiber optic cable out to the garage for future use.] (Update 2024 - a lot has changed here. LED lighting is king, wifi has made coax obsolete and cellular has the eliminated the need for land-line phones (at least in the garage). Consider going with a Sonos system for your music and mesh wifi to ensure a strong signal in the garage for your video steaming, cameras, thermostats and just about any other wireless device.)
PLUMBING -Water and plumbing is a nicety that I did not consider for my own garage because of the cost of running the pipes and sewer drains to a detached structure. However, if your garage is attached to the house, a wash sink (stainless steel is recommended) can be installed in one of your countertops along the outside wall (any outlet within 6' must be GFI protected) of the workshop. All water supply piping should be 3/4" L copper or stainless steel (many Europeans must use stainless for their plumbing). Drainage should be in PVC or stainless (cast iron is quieter but doesn't flow as well in the long run). Make sure all plumbing and vents are done to code and that any buried water supply lines to the garage are type K copper.
FLOOR DRAINAGE - I've seen far too many drainage systems that do not work properly....they are not vented, the drainage pipes are undersized, they don't have strainers to collect debris, and are often illegally connected to the home's sanitary (sewer) system. A proper floor drain in an existing or remodeled garage can be quite expensive ($5,000-6,000). The major cost component (the 1,000 gallon seepage tank to collect the water) is about half the total cost. New homes in many areas now require drywells/seepage tanks for runoff water collection so its not much more expensive to tie your garage drains in the drainage system for your roof's gutters. Still, the floor drains we use are not cheap ($500-600ea) but they are constructed of thick stainless steel and can easily handle 25,000 lbs of weight without damage. The debris collection basket is easily removed for cleaning. Drainage pipes should be 4" Schedule 40, pitched and vented properly. Always check with your plumbing inspector for any special code requirements in your area.
SAFETY & SECURITY - Make sure you've got a least 1 fire extinguisher per bay in your garage capable of dealing with electrical and chemical fires. A smoke and carbon monoxide detector are also advisable. Keep a first aid kit handy in one of your storage cabinets and chemical/oily rags should be kept in a fireproof container. For security, your garage can be put on a zone of your existing home alarm system or you can install a simple alarm with one contact device and one motion detector (use more for multiple bays and/or entrances). As mentioned before, access doors (excluding the garage door) should open out to make them difficult to kick in.
I'm sure that I've left a few things out (your comments and suggestions are welcomed). If you'd like me to help you design a future workshop or review or spec your current plans, please call or e-mail me. I can also supply many of the products mentioned above. Have fun - be safe!