1. INTRODUCTION

Construction research programs have been conducted at Battelle's Columbus Laboratories almost from its inception. The Construction Systems, Planning, and Economics Research Division, which has responsibilities in some of these areas, consists of engineers, architects, market analyses, and economists. We are currently involved with new construction methods and techniques: Development of design criteria; development of performance specifications for new products and components; evaluation and development of industrialized building systems; and conduct of conceptual architectural, financial, and planning research. It is an honor to have the opportunity to relate our work to that of the A62 Committee in delivering this paper on the current status of dimensional precoordination in the United States.

2. CURRENT STATUS OF DIMENSIONAL

PRECOORDINATION

Historically, aesthetic proportions and traditional building methods have been the main generators of dimension coordination. Aesthetic dimensions were highly developed into a series of coordinated proportions by the Greeks and Romans and were again popularized during the Renaissance. The building process has been an important generator of modular coordination as has the optimal size and weight of a component. For example, the proportion of bricks is based upon the shape, weight, and dimensions that are most easily grasped and laid by a mason.

The concept of dimensional coordination of manufactured components in the construction industry is directly tied to the 19th century industrial revolution. The traditional stick method of cutting and fitting each part of a building as a custom craft activity has only been replaced by the rationalized method of building using components and products that are premanufactured and then brought to the site for assembling. One of the earliest examples of industrialdimensional coordination and interchangeability was the gages for ammunition and guns developed in 1776

by French Lieutenant General Gribeauval. Similar developments in the United States were pioneered by Eli Whitney in 1800 when he produced rifles on the first assembly-line basis. English innovator of dimensional coordination, Joseph Whitworth, commented in 1856 on the effect of standardization in building components:

Suppose for instance, that the principal windows and doors of our houses were made only of three or four different sizes. Then we should have a manufactory startup for making doors, without reference to any particular house or builder. They would be kept in stock and made with the best machinery and contrivances for that particular branch; consequently, we should have better doors and windows at the least possible

cost.

Although modular coordination was introduced in the 1920's, it was not until the thirties that Albert Bemis outlined the idea of a full-dimensional coordination for the building industry based upon the use of components, the dimensions of which were multiples of a 4-inch module. The first standard for modular coordination was adopted in 1945 and the A62 Guide on Modular Coordination that first established 4 inches as the basic module was published in 1946 by the Modular Service Association. Since then, work was undertaken by the Modular Building Standards Association (MBSA) and more recently by the American National Standards Institute (ANSI) under the sponsorship of the National Bureau of Standards.

Currently the supply complex of the construction industry operates as a modified open system. In general, each building component or product is related by standards or tradition into functional groupings. Functional coordination by product type is well ilustrated by Sweets Catalogue or Graphic Standards. Coordination of dimensional standards and often performance criteria has been developed within most functional groupings by tradition, individual manufacturers, trade associations, institutes, or government agencies. The membership list of the A62 Committee is composed of over 55 such groups or individuals. Although the A62 Committee has just recently published basic module of 4 inches for horizontal dimen

sioning, dimensional coordination has been inherent within the construction industry.

Most products, however, are designed to be used in the custom building market where they are field adapted. Architectural and Engineering News recently estimated that cutting and fitting now takes from 5 to 45 percent of construction time. Many products are not universally used or interchanged from one project to another due to lack of coordination in joint design and/or standardize dimensions. Often components are part of a closed system due to the proprietary nature of the building industry and its supply complex. Curtain wall systems and metal building have much duplication, but little interchangeability. Within a closed system, interchangeability is not critical as all components and joints are designed to interface. In open systems, components coordination between different functional groups will allow for the installation of preassembled subsystems even if various manufacturers produce them. Interchangeable components could be removed, relocated, or replaced without destruction of the assembly itself or to other elements of the buiding.

When considering dimensional coordination, one must differentiate between different types of interface connection. J. F. Eden in England has referred to these differences as the "degree of restraint." In lap joints, stacking, or surface mounting, there is little restraint as long as the overall height or length is not critical. However, once assemblies have to fit together where their edges interface, dimensional coordination becomes critical.

The choice of a 4-inch module as the basis for the horizontal dimensioning of coordinated building components and systems conform to most current dimen

sional systems used in the construction industry. The system module selected in the U.S.A. Standard A625 was 60 M or 20 feet. Into this module, the factors of 2, 3, 4, 5, 6, 10, 12, 15, and 20 provide for component coordination. I shall now briefly review these factors and list how they conform to the dimensional system inherent in conventional building.

M (4") 1⁄2 M (2")

M, 2 M, 4 M (4, 8, 16′′)

3 M (12")

4 M (16")

5 M (20") 6 M (24")

10 M (40")

12 M (48")

15 M (60")

60 M (20 ft)

Basis for nominal dimensions of graded lumber, steel, and precast masonry.

Standard masonry nominal dimensions for brick, block, and related products.

Common increment of framing and component materials. Accepted spacing for stud wall construction.

12 metric module.

Standard width of precast masonry components (deck) and accepted stud spacing in selected materials. Nominal equivalent to the metric module, but has not been widely used in the United States. Most common component module for sheet materials, and also used in interior partition and integrated ceilings as planning module. Widely used as the basic planning module in integrated ceilings, office layout, and flexible partitions. Large enough for a systems module, yet flexible enough for multiple use. It has not been as widely used as the 12-ft. module which is generally used for mobile homes and sectionalized buildings. Currently most proprietary frame and box building systems do not conform to a specific set of dimensions.

Wherever I come into contact with the housing cene today I feel a growing sense of urgency. The pressure comes from many separate places. Where hese pressures come together and act in concert, something dramatic will surely happen.

Part of the pressure comes from the millions of amilies who are existing in substandard houses or apartments. In this age of rising expectations, fewer and fewer people are willing to accept substandard housing as their lot in life. If the Joneses' have it, and the Smith's don't, the Smith's want it; and they don't want to wait too long to get it. They are willing to work for it, and given the opportunity, they will work hard to pay for it. They want that opportunity.

Part of the pressure comes from the rise in population. Even if we get underway with a serious program of birth control in the next few years, we still will have a population of some 300 million in the United States by the year 2,000. We cannot really imagine 300 million people in this land of the great open spaces, but we know that as we move toward a population of this size the quality of life will be drastically impaired even if we solve our housing problem.

Part of the pressure comes from the increased urbanization of our society. Increasingly, we live in a manmade world, and if we neglect the amenities, comforts, and compensations, the effect on people will be increasingly severe. Housing is at the center of this problem; not just the immediate living unit, but the entire system for living-housing, services, streets, parks, communications, transportation. But the central problem is housing.

Housing has a special significance in the social revolution which is developing around us. The need for shelter is one of the most powerful psychological imperatives. The concept "home" not only has deep associations of warmth, comfort, and security; it also is part of a man's pride and his sense of status. If a man has a decent place to bring a wife, raise a family, and entertain his friends, he has a base for a feeling of personal worth, and for participation in the community. Force him by economic pressures or poor social planning into an overcrowded hovel, and his value to society declines with the erosion of his estimate of himself.

It is pressures such as these which are generating a new sense of urgency in the housing field. That is why government and industry are taking a harder look at housing problems than ever before. And I think we are gaining some insights which may help to remove the obstacles which still stand in our way.

Some of the problems which are now emerging have been there all the time, but they have been hidden by the complexity of the industry and the traditional building process. Uncertainty, for example, anywhere in the building process runs up overhead and in

creases costs.

If a builder is uncertain about the number of orders he will receive in the months ahead, he will necessarily schedule his work to keep his people busy. Payrolls have to be met, and if he lets people go in slack seasons they may be hard to replace. So he tends to stretch out work in busy seasons to fill in gaps in slack seasons. It is not the most economical way to build houses, and it makes some customers angry with him, but under the present system he has no choice.

In the same context, he has to bid as high as he safely can on a job because he knows that when it is completed he will have to tide himself over until the next contract is secured. Since most contractors are in the same boat, prices tend to push against "what the traffic will bear.'

If builders knew that they could depend on a share of a large volume of new houses they could approach both problems in a more businesslike way.

When a new product is introduced into the construction market a new material or component-it may represent long-range benefits, but its immediate effect may be to create uncertainty. Consider the building inspector. We complain about restrictive building codes, and with good cause; but the problem goes beyond the code itself. If you want to build a house which does not conform to the city code, but in fact represents an improvement over the code, the building inspector has a problem. He has no one to whom he can turn for expert advice; no one who can guarantee that the house will be safe if he approves the innovation. Furthermore, if he approves the house outside the code, and the house is sold, and the new owner has an accident traceable to the innovation, the inspec