Design Parameters

Garage Plans by Behm Design may be used in most US locations and some in Canada. The design parameters we use are assessed as the “normal” range and those parameters work for most locations. The plans are not guaranteed to be usable in locations with extreme environmental conditions requiring high-level design parameters. Our design parameters include:

Normal Range Design Parameters:

  • Comply with the International Residential Code (IRC) using the prescriptive (non-engineered*) approach
  •  Wind Speed: 100 mph in 3 seconds gusts with moderate “B” exposure for most plans. (some of out early garage plans were engineered using a basic wind speed of 85 mph)
  • 2×4 light wood framed construction (also called “conventional”) with rafters or manufactured trusses
  • Flat building site condition is assumed
  • Soil bearing capacity of minimum 1500 #/sf
  • Seismic risk category “C” as per IRC code (although a very few of the larger plans comply with “B” which is less severe)
  • Snow load specification of 30 lbs/sf

Important Information:

Before ordering your garage plans one should contact local Planning (or Zoning) and county or city Building Department to learn of special requirements or restrictions that relate to the garage project you propose. A Plot Plan (or Site Plan) is typically required to show proposed improvements and their locations on the property. Some building departments only require a fee and project statement to get the permit. Most others have a required plan review process to verify that proposed building will satisfy local building and other codes and one usually needs to give them 2 plan sets to review. A permit coordinator/technician can provide all information needed to begin the process.

It is unusual for building departments to require plan certification (stamped) by a state-licensed architect or engineer) as the prescriptive approach to code compliance is the standard). However, locations with the severe designated parameters for wind, seismic (earthquake) and snow often will need engineered documentation of loads analysis to guarantee structural capacity of the garage. They do calculations/analysis and then mark-up the plans as needed for structure upgrade if necessary.

The typical wall construction shown in Behm Design plans is 2 x 4 @ 16 inches on center with a single pressure-treated bottom plate and continuous wall double top plates. The stud spacing may be increased to 24 inches on center which is the limit for this kind of wall framing prescribed. However, 24 inches is the specification in the Economy Garage Plans category offered by Behm Design.

Exceptions include for climates having extreme temperatures the local authority may require 2 x 6 wall framing to maximize insulation capacity. Plans which include living areas show that insulation and HVAC be installed. In those cases, the plans show 2 x 4 or 2 x 6 as alternate if preferred or required higher than standard framed walls are those which exceed the code limit of 10 feet for bearing walls. Some local authorities will allow increasing to 12 feet if the studs are then 2 x 6 spaced at 16 inches on center and others may require that the stud bearing be certified by an engineer. And certification will always be needed if bearing wall height exceeds 12 feet.

Typical Wall Construction: 2 x 4 framed, conventional wall construction is used typically in building garages. Garage plans by Behm Design specify with studs’ spacing at 16 inches on center. A single, pressure-treated wall-bottom plate and a double, continuous wall-top plate comply with IRC code prescriptive requirements for wall framing. Stud spacing may be as much as 24 inches on center as code allows and is the specification unique to the Economy-Garage Plans collection of Behm Design.

Exceptions: Climates which have extreme heat and cold temps may require the use of 2 x 6 framing for walls, as this allows for optimal batt insulation thickness. However, if the garage is not to be heated or cooled the project may be exempt from that requirement. Our garage plans with apartments show options for either 2×6 or 2×4 framing so yo can comply with codes as applicable in your location.

Tall Framed Walls: If bearing wall heights are greater than 10 feet your local building authority could require having it certified for stud bearing capacity. Alternatively, the inspector/building authority may allow simply switching to 2 x 6 wall-framing even though it is not expressly written/addressed in the building code.

Wall Stud Spacing for Practicality: 16 inch on center framing spacing’s has been around for a long time as conventional practice. It gives three spaces for every 4 ft. and is a module applied to lumber, panels and support assemblies. Shelf supports how much more weight with 16 Inch instead or 24-inch frame spacing. For cabinets, racks, shelves, pegboards and ledgers the 16″ frame spacing is ideal.

PRESCRIPTIVE APPROACH: (or CONVENTIONAL)

Rather than having your garage plans prepared by a state-licensed engineer or architect the IRC/IBC building codes allow using their prescriptive (prescribed) measures instead as presented in their tables and text content. Nearly all aspects of a building may be made compliant if it is built according to the code for foundations, floor, walls, and roof. There are many limits pertaining to building dimensions, shape, structure-type, and location proximity. There are also limiting factors for snow, earthquake risk and the wind. There are useful tables for lumber framing spans for floors and roofs as well as wall height limits. The lateral design is satisfied by their Braced Wall Construction measures if applied prescriptively. Much test data has referenced wood species, grades and capacities and repetitive applications for framing, including both dead and live loads. Using the Prescriptive approach can save lots of cost and time usually associated with consulting state-licensed professionals.

ENGINEERED APPROACH:
(or CERTIFIED)

If a garage plan design exceeds shape and/or size limits on the prescriptive approach (or the plans were drawn without proper code compliance) then the design justifications and certification by a state-licensed engineer or architect is usually required in acquiring a building permit. They typically analyze the forces which can act on the building structure, then add mark-up notes and any revisions to the plans as they require to certify with their stamp. Engineered calculations are often required by the Building Official as part of the permit submittal.

Behm Design uses the prescriptive approach for most of the garage plans. They are usable unless the locally established design parameters for snow, wind, and earthquake exceed our stated parameters shown on the plan set cover sheet, if not a professional can always certify.

Building your new garage in a coastal region may have additional requirements as compared to inland. California and Washington State, for example, has many seismic high-risk zones. Some areas also have high wind speed and exposures or both may apply. Texas, Florida, Louisiana and the east coast states face possible hurricane events. These conditions set the design parameters (lateral and uplift forces) much higher than standard assumed by most quality stock garage plans, including those by Behm Design. The plans, to upgrade them for severe conditions should be taken to a local architect or P.E. (professional engineer) licensed in the state for their force analysis, mark-ups of the stock plan, and certification by stamp or seal. They usually add more strap type hardware and, increase foundation size and re-bar size and sometimes, revise shear wall nailing scheme to increase overall strength to resist forces. This kind of service is readily available in places with these conditions and fees vary.

Your local building authority can advise you of local design parameters used and you can compare to those of Behm Design plans. Please call Jay Behm at 1-800-210-6776 if you have questions.

Behm Design plans are not pre-engineered for the severe parameters and does not offer engineering services for plan upgrades.

Behm Design’s garage plans are not designed specifically to the Canadian Building Code. They are designed to the IRC IBC codes in the US. However, our plans have been permitted and build many times in all provinces except Ontario. (Ontario has its own special registration requirement and Behm Design is not registered) There are some areas in British Columbia that have the same kind of wind and/or earthquake engineering requirements as further south in coastal US regions.

As in the US our plans are money-back guaranteed for purchase and may be returned for refund if they cannot be used

In New Jersey, there are some jurisdictions requiring that garage plans be stamped by NV architect or engineer (or certified). Customers have reported to me that they were allowed to submit plans as their own and assuming liability and that then waives the certification requirement. If you plan to build a garage in NJ visit your local building dept. and get the requirements for plans submittal and building permit. If certification of the plans is required you will find local professionals able to provide that service.

The state of Nevada has unique requirements for the design of buildings and the drawings. The work submitted for building permit review is supposed to be created by ad architect, engineer or designer licensed in Nevada. Because Behm Design does not have the required license for Nevada its plans would not be usable. However, I have had customers say that some exceptions to this rule do exist. You can check with your local building department if plan certification can be done under their policy. If you do purchase one of our plans and they cannot be used we will refund the purchase price.