Home Specifications

Hand-in-hand with the graphical design are the specifications, often referred to in short-hand as “specs.”  These are written descriptions of the materials and equipment to be used in your home and the methods to be used in assembling them together.  For every design there are many ways to build it.  The specifications may be embedded in the plans.  Occasionally, they are included in a contract form.  More often, they are contained in a separate document.  The specifications may reference other documents such as building codes and national standards, and may include drawing details and photos to convey their intent.  Specifications may be very broad, indicating that a range of materials are acceptable, and in other instances approve only a particular material by a particular company and indicate a part number and color or finish.

Building codes: The most important specification is the reference to the building code that will apply to your home.  Building codes have been developed over time, primarily to protect the safety of occupants, neighbors and people building and maintaining the home.  More recently, they have also established standards for energy efficiency, water usage, air quality, and sustainable materials.  Building codes typically mandate that certain materials and equipment must have been tested and certified to meet certain recognized standards.  We build single-family homes under five broad categories of building codes.

International Residential Code (US):   In the United States, if you build a home completely on site to be occupied by one, two or three families, it will have to meet a local version of the International Residential Code, usually referred to as the “IRC.”  Every state has established regulations governing the application of their version of the code to homes largely built in a factory.  Homes built in a factory under these regulations are commonly called “modular” or “pre-fabricated” homes.  All of the provisions of the code apply to our modular homes.  The state regulations establish how the designs and specifications for such homes are approved and how the work done in the factory is to be inspected by an authorized independent entity.  (Work performed at the building site is still inspected by a local building inspector.)  Once upon a time there were multiple model building codes on which the states based their local versions with northern states focused on handling the weight of snow and cold weather, southeastern states focused on hurricane winds and warm moist conditions and the western states focused on earthquake safety.  At the end of the twentieth century these variations, which had a lot of overlap, were all brought together by an umbrella not-for-profit organization, the International Construction Council.  All states have adopted some form of the IRC, usually with some variations.  In most states, their version of the code applies everywhere, but some allow some degree of county or city variation.  An example is Illinois, where Chicago, Cook County and surrounding counties have their own building codes.  We warrant that modular homes we build will meet the state version of the code.  We ask that your builder determine if there are any local variations or applicable zoning regulations and covenants and provide us with the details.

National Building Code of Canada/CSA-A277:   As required by federal legislation, all provinces and territories have adopted construction standards for permanent homes built on-site based on the National Building Code of Canada (“NBC”), which is developed by the Institute for Research in Construction, an arm of the National Research Council of Canada.  The Canadian Standards Association (“CSA”) has developed regulations for the application of the code to homes largely built in a factory and inspection of the homes in the factory.  The CSA-A277 standard specifically applies to homes intended to be permanent structures, but with significant on-site work.  Homes built in a factory under these standards are commonly called “modular” or pre-fabricated” homes.   The NBC has a strong emphasis on energy efficiency and protection from moisture damage.  There are details that vary among the provinces, which also allow varying degrees of local discretion.  There are also significant variations introduced by the various provincial hydro-electric utilities.  We warrant that the modular homes we build will meet the provincial version of the code and rely on your builder to determine if there are any local variations.

Manufactured Housing Construction and Safety Code (US):  This national code was established in 1975 and replaced a hodgepodge of state and voluntary codes for what were then called “mobile homes.”  Since this code is administered by the US Department of Housing & Urban Development (“HUD”), it is usually referred to as the “HUD code.”  Homes built under this code are limited to single-family homes, must be nearly completed in the factory with regard to structure, heating equipment, and finishes such as siding, roofing and interior wall and ceiling materials.  Homes built under this code are officially called “manufactured homes,” but many people still refer to them as “mobile homes” or even “trailers,” the last term creating some confusion with towable recreational vehicles built under state and voluntary codes.  While many manufactured homes are sited on leased land and are treated as personal property, many others are placed on permanent foundations and may be treated as real estate.  However, the code requires that all manufactured homes must be built on a transportable chassis, usually a steel frame, so that they are at least capable of being relocated.  The HUD code is a national pre-emptive standard, and state and local variations are not permitted except for foundation guidelines.  HUD contracts with independent engineering firms to certify that the home design conforms to the code and to inspect the manufactured home in the plant while it is being built.  Compared to the IRC the HUD code has more sections permitting a wide variety of materials and methods that meet a performance standard and fewer sections mandating specific materials and methods, which allows some cost savings.  While it is possible to build a 1-1/2 story or 2-story HUD-code home, it is almost always not cost-effective because of the mandated transportation chassis, unless there is some local advantageous tax treatment.

Canadian Relocatable Homes/CSA-Z240, Z241 and A277 on-frame:  “Manufactured” and “mobile” homes in Canada, that is, homes with integral chasses accommodating one or more relocations, are designed and produced under several standards developed by the Canadian Standards Association (“CSA”).  These standards closely follow the National Building Code of Canada with the addition of standards for the transportation frame which emphasize structural performance and over-the-road safety.  The Z240 standard requires that the home be completed to the extent possible in the factory.  There are relatively few provincial, territorial and local variations, and most provinces have implemented Z240 with less aggressive energy-efficiency standards than for under the A277 standard.  The Z241 standard is similar and applies to smaller homes typically called “park models.”  It is possible and even common to build an A277 modular home with the Z240 transportation frame standard.  These homes are usually referred to as “on-frame modular” homes.  They must conform to all of the provincial, territorial and local variations in the National Building Code, but can take advantage of the greater flexibility of the NBC in the work performed at the building site.  This version of the A277 standard is often used in remote areas and where a traditional foundation is problematic (e.g. permafrost).

Other Codes:  Our company exports some homes outside the US and Canada, and is then subject to other codes.  Our company also builds multi-family and commercial structures in the US and Canada under the applicable codes.