Modular building

Two-story modular dwelling

Modular buildings and modular homes are sectional prefabricated buildings or houses that consist of multiple modules or sections which are manufactured in a remote facility and then delivered to their intended site of use. The modules are assembled into a single residential building using either a crane or trucks.

Modular buildings are considerably different from mobile homes. Off-frame modular dwellings differ from mobile homes largely in their absence of axles or a frame, meaning that they are typically transported to their site by means of flat-bed trucks; however, some modular dwellings are built on a steel frame (on-frame modular), which can be used for transportation to the site. Many modular homes are of multi-level design, and are often set in place using a crane.

Uses

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Modular home in Sutton, Alaska

Modular buildings have a wide variety of uses. They will either be used for long-term temporary or permanent facilities. Such uses include construction camps, schools and classrooms, civilian and military housing needs, and industrial facilities. Modular buildings are a perfect solution in remote and rural areas where conventional construction may not be reasonable or even possible. Other uses have also been found for modular buildings including churches, health care facilities, sales and retail offices, fast food restaurants and cruise ship construction.

Construction process

Modular components are typically constructed within a large indoor facility on assembly lines much like Henry Ford originally instituted with his automobile company. Such facilities use an assembly line track to move the modules from one workstation to the next. Independent building inspectors are on site to supervise the construction and ensure that all building codes are adhered to during assembly.

The modules that will combine to form the house are assembled off-site in a factory. These modules can take one to three months to be constructed but often take as little as 10 days actually to construct when they are first started. Then they are transported to the building site where a crane is brought in to assemble the modules together. The placement of the modules together generally takes several hours or days. Once assembled, modular buildings are essentially indistinguishable from typical site-built homes. While mobile manufactured buildings often decrease in value over time, a well-built modular should have the same longevity as its site-built counterpart, increasing in value over time.

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  Bulk materials
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  Walls attached to floor
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  Ceiling drywalled in spray booth
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  Roof set in place
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  Roof shingled and siding installed
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  Ready for delivery to site

Advantages

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Modular homes allow the adding and replacing of house sections

Modular buildings are very affordable because of the factory construction of these buildings. They are very cost effective compared to conventional construction. These units are typically constructed in an enclosed facility, therefore weather is not a factor in the construction time line. Material delivery fees are also out of the equation because an ample amount of material will always be available at the facility, as opposed to being delivered in limited quantities to the job site, nearly eliminating construction delays, and theft of building materials from the site.

Such dwellings are often priced lower than their site-built counterparts and are typically more cost-effective to builders and consumers. These new homes can be constructed in less time than it takes to build a home "on-site". Manufacturers cite the following reasons for the typically lower cost/price of these dwellings:

• Speed of Construction/Faster Return on Investment - modular construction allows for the building AND the site work to be completed simultaneously, reducing the overall completion schedule by as much as 50%.
• Indoor construction. Assembly is independent of weather which increases work efficiency and avoids damaged building material.
• Favorable pricing from suppliers. Large-scale manufacturers can effectively bargain with suppliers for discounts on materials.
• Ability to service remote locations. Particularly in countries such as Australia there can be much higher costs to build a site-built house in a remote area or an area experiencing a construction boom such as mining towns. Modular homes can be built in major towns and sold to regional areas.
• Low waste. With the same plans being constantly built, the manufacturer has records of exactly what quantity of materials are needed for a given job. While waste from a site-built dwelling may typically fill several large dumpsters, construction of a modular dwelling generates much less waste.
• More environmentally friendly construction process - modular construction generates less materials waste and less site disturbances than comparable site built structures.

Market acceptance

Raines Court, a multi-story modular housing block in Stoke Newington, London. One of the first two such residential buildings in Britain. (December 2005)

Some home buyers and some lending institutions resist consideration of modular homes as equivalent in value to site-built homes. While the homes themselves may be of equivalent quality, entrenched zoning regulations and psychological marketplace factors may create hurdles for buyers or builders of modular homes and should be considered as part of the decision-making process when exploring this type of home as a living and/or investment option. In the UK & Australia modular homes have become quite accepted in regional areas however are not commonly built in major cities. Some modular building manufacturers have begun to refer to modular buildings as “off-site construction” to combat the negative image of modular which is due to portables or trailer stereotypes. Recent innovations allow modular buildings to be indistinguishable from site built structures.

Modular homes vs. mobile homes

Differences include the building codes that govern the construction, types of material used and how they are appraised by banks for lending purposes. The codes that govern the construction of modular homes are the exact same codes that govern the construction of any site constructed home. In the United States, all modular homes are constructed according the International Building Code (IBC), IRC, BOCA or the code that has been adopted by the local jurisdiction.

Mobile homes (manufactured homes) are constructed according to the HUD Code and are generally considered lesser quality. The materials are the same as site constructed homes. Wood frame floors, walls and roof is the most typical. Some modulars even included brick or stone exteriors, granite counters and steeply pitched roofs. All modulars are designed to sit on a perimeter foundation or basement. Mobile homes are constructed with a steel chassis that is integral to the integrity of the floor system. Mobile homes often require special lenders. Most companies have standard plans. However, all modular buildings can be custom built to a clients specifications. Today's designs include multi-story units, multi-family units and entire apartment complexes. The negative stereotype commonly associated with mobile homes and has prompted some manufacturers to start using the term Off-Site Construction.

Standards and zoning considerations

Typically, modular dwellings are built to local state or council code, so dwellings built in a given manufacturing facility will have differing construction standards depending on the final destination of the modules . Steel and/or wood framing are common options for building a modular homes. Modular home designs can be customized for local zoning codes. For example, homes built for final assembly in a hurricane prone area can have additional bracing built-in to meet local building codes.

Some US courts have ruled that zoning restrictions applicable to mobile homes do not apply to modular homes since modular homes are often assembled with a permanent foundation. Additionally, in the US, valuation differences between modular homes and site built homes are often negligible in real estate appraisal practice; thus, modular homes can in some market areas (depending on local appraisal practices per Uniform Standards of Professional Appraisal Practice) be evaluated the same way as traditionally built dwellings of similar quality. In Australia Manufactured Home Parks are governed by additional legislation that does not apply to permanent modular homes. Possible developments in equivalence between modular and site-built housing types for the purposes of real estate appraisals, financing and zoning may increase the sales of modular homes over time.

Building strength

According to manufacturers, modular homes are generally designed to be initially stronger than traditional homes by, for example, replacing nails with screws and adding glue to joints. This is supposed to help the modules maintain their structural integrity as they are transported on trucks to the construction site. Despite manufacturer claims that the modular home is initially built to be stronger than a traditional home, it is difficult to predict the final building strength since it needs to endure transportation stresses that traditional homes never experience.

When FEMA studied the destruction wrought by Hurricane Andrew in Dade County Florida, they concluded that modular and masonry homes fared best compared to other construction.

Typically, a modular home contains about 10% to 20% more lumber compared to traditional stick-built homes. This is because modules need to be transported to the job site and the additional lumber helps keep them stable.

Surfaces and finishes

Modular buildings can be assembled on top of multiple foundation surfaces, such as a crawl space, stilts (for areas that are prone to flooding), full basements or standard slab at grade. They can also be built to multi-story heights. Motels and other multi-family structures have been built using modular construction techniques. The height that a modular structure can be built to depends on jurisdiction but a number of countries, especially in Asia, allow them to be built to 24 floors and possibly even more.

Exterior wall surfaces can be finalized in the plant production process or in the case of brick/stone veneers field applications may be the builders choice. Roof systems also can be apart of – separate from – applied in the field after the basic installation is completed.

Eco-Friendly construction

Efficient green solution is very interested and combined into various kind of commercial products.

Modular building is also environmentally reasonable choice for the construction industry designed specifically to suit any tailor-made requirement in controlled environment. With its strength features; re-usability, less site interference and waste, efficiency in material management, completed ventilation system reduced percentage of formaldehyde, and quicker build times compared to site-built construction.

Modular construction are substantially than stick-built construction and more energy efficient.

How are modular structures more beneficial?

Modular construction techniques have been shown to be inherently advantageous in 7 major areas:Modular.org

1. Less Materials Waste – Pre-fabrication makes it possible to optimize construction materials purchases and usage while minimizing on-site waste and offering a higher quality product to the buyer. Bulk materials are delivered to the manufacturing facility where they are stored in a protected environment safe from theft and exposure to the environmental conditions of a job site.
2. Less Material Exposure to Inclement Weather – Many of the indoor air quality issues identified in new construction result from high moisture levels in the framing materials. Because the modular structure is substantially completed in a factory-controlled setting using dry materials, the potential for high levels of moisture being trapped in the new construction is eliminated.
3. Less Site Disturbance – The modular structure is constructed off-site simultaneous to foundation and other site work, thereby reducing the time and impact on the surrounding site environment, as well as reducing the number of vehicles and equipment needed at the site.
4. Safer Construction – Modular construction is a safer alternative. Conventional construction workers regularly work in less than ideal conditions dealing with temperature extremes, rain, wind, or any combination of natural conditions. This, by its very nature, is a much more challenging environment to work safely in. Additionally, the potential for injury including falls, the most common work site risk, is much higher. In a factory controlled setting, each worker is typically assigned to a work station supplied with all the appropriate equipment needed to provide the safest work environment possible. Off-site construction also eliminates the hazards associated with materials, equipment and an incomplete construction processes typical of construction sites that can attract curious and unwelcome “visitors” (i.e. students on a school expansion project).
5. Flexibility – When the needs change, modular buildings can be disassembled and the modules relocated or refurbished for their next use reducing the demand for raw materials and minimizing the amount of energy expended to create a building to meet the new need. In essence, the entire building can be recycled in some cases.
6. Adaptability – Modular buildings are frequently designed to quickly add or remove one or more “modules” minimizing disruptions to adjacent buildings and surroundings.
7. Built to Code With Shorter Build Times – The bottom line is that with modular construction you can get a facility built to the same local codes with construction quality as good as or better than a comparable site built building in much less time. Additionally, the abbreviated construction schedule allows you to get a return on your investment sooner while minimizing the exposure to the risks commonly associated with protracted construction schedules.

See also

• Prefabricated home
• Manufactured housing
• Stick-built home
• Toter
• NTA Inc

External links

• Modular Building Systems Association – National trade association representing the legislative and regulatory interests of the modular housing industry
• National Association of Home Builders (United States)
• National Modular Housing Council National Trade Association for the Modular Housing Industry
• ModularCenter.com Modular Homes National network of modular home builders & manufacturers along with general information on modular homes and a large database of modular home plans
• Modular Building Institute – International trade association representing non residential modular construction professionals