Methods of Wood Frame Construction
In the past there was just one way to have a wood frame house built, and that was stick built. Now there are several: stick built, panelized, modular or a combination. The biggest difference between these three methods is the extent to which technology is applied during the building process and the level of sophistication used to complete the house. In its earliest form, wood frame housing was built at the job site using basic construction tools. As builders became increasingly sophisticated, they borrowed ideas from the automobile industry. Individual components were built off-site, and delivered to the job site as a sub-assembly. Initially these sub-assemblies were flat panels. Over time the sub-assemblies grew to where entire modules were factory built for delivery to the job site. This form of construction ultimately came to be called the modular building system.
Stick-Built
A large percentage of homes today are still constructed using the low-tech stick built system. Builders rely on basic hand tools following the same process used for hundreds of years. While most stick built homes are well built, the real down side to a stick built home comes at the expense of the home buyer. Longer construction times, increased risk of water damage, questionable structural quality, higher construction loan interest costs, and additional out-of-pocket housing costs increase both the total net cost and the risks to building a new home.
As with any new house, the building lot is first selected, cleared and prepared for a foundation. With the foundation in place, construction starts on the home, beginning with the floor. On a stick by stick basis, first the floor, then the walls, ceiling and roof are built. Workers cut and nail each board in place, one after the other. It is a manually intensive, often inexact process.
The builder follows a basic house plan drawn up by an architect or house designer. The process is simple and allows the builder to make adjustments as the house is built. It is not uncommon for builders to have to make design changes on-the-fly to overcome inaccurate designs. This is perhaps the biggest advantage offered by a stick built wood frame home. As the house is built, the builder can continually compensate for previous errors and adjustments as the structure is built. The ability to compensate for errors in the building process sounds like a fine idea, but how many of us would buy an automobile knowing that the manufacturer had modified parts on-the-fly to compensate for irregularities? In this age of precision technology why should a $100,000 house be any less precise than a $20,000 automobile? Fortunately the age of technology has advanced in the home building business.
This leads to the issue of structural quality. In the vast majority of cases, the structural quality of a stick built home is more than adequate, but with the dual motivations of protecting the structure from water, and completing the home quickly to make a profit, some homes have an inadequate structure. Regretfully, once the exterior siding and interior drywall are installed, it is virtually impossible to determine whether the structure is truly sound. Most people make the assumption that if the house is standing, the structure is fine. While this may be true in most cases, home owners in the hurricane destroyed areas of Homestead Florida will beg to differ. According to many news reports, poor structural quality represented the leading cause of failure during the Florida hurricane. Regretfully some builders have a lack of concern for the structural quality of a house, taking short-cuts to reduce costs and speed completion time.
The desire to defend the inexact process of stick building can sometimes take on extreme positions. An individual I know once commented that he wanted a stick built home because if the foundation was not level, it allowed the house to compensate for the faulty foundation. Since a foundation can cost upwards of $10,000 or more, I would not accept a poorly leveled foundation. In my mind, the ability to compensate for poor workmanship is not a wise reason for selecting a building system.
Water is another enemy stick builders have to address. To minimize the potential for water damage, builders often rush to get the frame up and water tight. The faster the home is shielded from water damage, the less the structure will warp. Nail pops are the most common problem of warping wood, but wavy walls, floors and ceilings can occur. Except for homes built in the desert, a stick built home most likely has some form of water damage from the construction process. Builders are in a difficult position. They can push to complete and water tight the exterior shell at the expense of compromising the structural integrity of the house. Or, they can focus on building a structurally superior house frame, at the risk of water damage. Builders will insist they do both, but unless they build in a climate controlled environment how can they. Some one's house will caught in the rain. And we know from the reports in Homestead Florida that many houses were never built in a structurally sound manner. Unfortunately, home buyers never know until it's too late.
Increasing demand, calls for improved quality and the need to reduce construction time have lead many builders to adopt advanced technology in place of the low technology stick building system. The first step in this process was the introduction of precision built panels. Panelized construction utilizes similar construction techniques as stick built homes, but accelerates the process by pre-fabricating many of the components used to build a house. Modular construction builds upon the panelized approach, but takes it to a higher level. Panelized construction emphasizes the use of flat panels such as wall sections, window and door frames and roof trusses which are essentially two-dimensional. Modular construction takes the pre-assembled panelized approach to the next level and builds them into a three-dimensional module.
Panelization
Stick built homes suffer from a high degree of waste wood, growing labor costs, and vandalism. In an effort to reduce some of these costs, sophisticated builders borrowed a concept widely used by automobile manufacturers. Car manufacturers first manufacture sub-assemblies, and then build the final product from the sub-assemblies. Home builders realized that by breaking down a home into individual panels, the structural shell could be built off site, and assembled at the job site just like an automobile. The job site become the final assembly plant. Using panels both the builder and the home buyer benefit. Using a manufacturing environment, builders control the quality of each panel ensuring the structural integrity of each house. Water damage was equally minimized through the use of panels. A house frame could be assembled and water tight within a matter of days, not months like a stick built home.
Today, many stick builders use some form of panelization. The degree of panelization a home might have ranges from the complete structure, to just a small number of components. The three most common use of prefabricated components includes pre-hung windows, pre-hung doors and roof trusses. Engineered roof trusses provide a builder with a strong roof system that goes up much quicker than a stick built roof, while providing equal or better strength. Other builders utilize engineered floor joists in place of the traditional solid wood joists. In the past engineered trusses and floor joists were often more expensive than standard dimensional lumber, but as the cost of long dimensional lumber continues to increase, the use of engineered materials is sure to increase.
Engineered Components
To increase the strength of your home's roof system while
lowering the total cost, builders
incorporate the use of roof trusses. Roof trusses are engineered
components designed to carry the weight of the roof from two end points, just
like a bridge. In fact, one of the earliest uses for engineered trusses was for
building bridges. If you have ever
traveled on the back roads of America, you were sure to cross one of those
green, steel framed, arched bridges. An
engineered truss supports large weight loads utilizing smaller components
precisely placed based on well tested mathematical formulas. With declining lumber resources, the use of
engineered wood trusses in home construction will only increase.
Home buyers benefit in many ways. Lower material costs reduce the total cost of
the home. This allows the home buyer to get more for his money. Faster completion time further reduces total
labor costs while shortening the house's exposure to the elements. The
environment also benefits from a reduced drain on the timber resources. Trusses take advantage of science, not sheer
strength to carry the weight. Smaller
wood pieces are more readily available, often being too small for traditional
jobs. So, when the builder uses engineered components your getting a stronger
home at a lower cost while helping the environment.
