2008 National Building Cost Manual
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Introduction | Table of Contents | Back Cover

by Dave Ogershok

Explanation of the Cost Tables This manual provides construction or replacement costs for a wide variety of residential, commercial, industrial, agricultural and military buildings. For your convenience and to avoid possible errors, all the cost and reference information you need for each building type is listed with the primary cost figures for that building. After reading this and the following two pages you should be able to turn directly to any building type and make an error-free estimate or appraisal. The costs are per square foot of floor area for the basic building and additional costs for optional or extra components that differ from building to building. Building shape, floor area, design elements, materials used, and overall quality influence the basic structure cost. These and other cost variables are isolated for the building types. Components included in the basic square foot cost are listed with each building type. Instructions for using the basic building costs are included above the cost tables. These instructions include a list of components that may have to be added to the basic cost to find the total cost for your structure. The figures in this manual are intended to reflect the amount that would be paid by the end user of a building as of mid 2007. They show the total construction cost including all design fees, permits, and the builder's supervision, overhead, and profit. These figures do not include land value, site development costs, or the cost of modifying unusual soil conditions or grades. Building Quality Structures vary widely in quality and the quality of construction is the most significant variable in the finished cost. For estimating purposes the structure should be placed in one or more quality classes. These classes are numbered from 1 which is the highest quality generally encountered. Each section of this manual has a page describing typical specifications which define the quality class. Each number class has been assigned a word description (such as best, good, average or low) for convenience and to help avoid possible errors. The quality specifications do not reflect some design features and construction details that can make a building both more desirable and more costly. When substantially more than basic design elements are present, and when these elements add significantly to the cost, it is appropriate to classify the quality of the building as higher than would be warranted by the materials used in construction. Many structures do not fall into a single class and have features of two quality classes. The tables have “half classes” which apply to structures which have some features of one class and some features of a higher or lower class. Classify a building into a “half class” when the quality elements are fairly evenly divided between two classes. Generally quality elements do not vary widely in a single building. For example, it would be unusual to find a top quality single family residence with minimum quality roof cover. The most weight should be given to quality elements that have the greatest cost. For example, the type of wall and roof framing or the quality of interior finish are more significant than the roof cover or bathroom wall finish. Careful evaluation may determine that certain structures fall into two distinct classes. In this case the cost of each part of the building should be evaluated separately. Building Shapes Shape classification considers any cost differences that arise from variations in building outline. Shape classification considerations vary somewhat with different building types. Where the building shape often varies widely between buildings and shape has a significant effect on the building cost, basic building costs are given for several shapes. Use the table that most closely matches the shape of the building you are evaluating. If the shape falls near the division between two basic building cost tables, it is appropriate to average the square foot cost from those two tables. Area of Buildings The basic building cost tables reflect the fact that larger buildings generally cost less per square foot than smaller buildings. The cost tables are based on square foot areas which include the following: All floor area within and including the exterior walls of the main building.   Inset areas such as vestibules, entrances or porches outside of the exterior wall but under the main roof.   Any enclosed additions, annexes or lean-tos with a square foot cost greater than three-fourths of the square foot cost of the main building. Select the basic building cost listed below the area which falls closest to the actual area of your building. If the area of your building falls nearly mid-way between two listed building areas, it is appropriate to average the square foot costs for the listed areas. Wall Heights Building costs are based on the wall heights given in the instructions for each building cost table. Wall height for the various floors of a building are computed as follows: The basement is measured from the bottom of floor slab to the bottom of the first floor slab or joist. The main or first floor extends from the bottom of the first floor slab or joist to the top of the roof slab or ceiling joist. Upper floors are measured from the top of the floor slab or floor joist to the top of the roof slab or ceiling joist. These measurements may be illustrated as follows: Square foot costs of most building design types must be adjusted if the actual wall height differs from the listed wall height. Wall height adjustment tables are included for buildings requiring this adjustment. Wall height adjustment tables list square foot costs for a foot of difference in perimeter wall height of buildings of various areas. The amount applicable to the actual building area is added or deducted for each foot of difference from the basic wall height. Buildings such as residences, medical-dental buildings, funeral homes and convalescent hospitals usually have a standard 8-foot ceiling height except in chapels or day room areas. If a significant cost difference exists due to a wall height variation, this factor should be considered in establishing the quality class. Other Adjustments A common wall exists when two buildings share one wall. Common wall adjustments are made by deducting the in-place cost of the exterior wall finish plus one-half of the in-place cost of the structural portion of the common wall area. If an owner has no ownership in a wall, the in-place cost of the exterior wall finish plus the in-place cost of the structural portion of the wall should be deducted from the total building costs. Suggested common wall and no wall ownership costs are included for many of the building types. Some square foot costs include the cost of expensive veneer finishes on the entire perimeter wall. When these buildings butt against other buildings, adjustments should be made for the lack of this finish. Where applicable, linear foot cost deductions are provided. The square foot costs in this manual are based on composite costs of total buildings including usual work room or storage areas. They are intended to be applied on a 100% basis to the total building area even though certain areas may or may not have interior finish. Only in rare instances will it be necessary to modify the square foot cost of a portion of a building. Multiple story buildings usually share a common roof structure and cover, a common foundation and common floor or ceiling structures. The costs of these components are included in the various floor levels as follows: The first or main floor includes the cost of a floor structure built at ground level, foundation costs for a one-story building, a complete ceiling and roof structure, and a roof cover. The basement includes the basement floor structure and the difference between the cost of the first floor structure built at ground level and its cost built over a basement. The second floor includes the difference between the cost of a foundation for a one-story building and the cost of a foundation for a two-story building and the cost of the second story floor structure. Location Adjustments The figures in this manual are intended as national averages for metropolitan areas of the United States. Use the information on page 7 to adapt the basic building costs to any area listed. Frequently building costs outside metropolitan areas are 2% to 6% lower if skilled, productive, lower cost labor is available in the area. The factors on page 7 can be applied to nearly all the square foot costs and some of the "additional" costs in this book. Depreciation Depreciation is the loss in value of a structure from all causes and is caused primarily by three forms of obsolescence: (1) physical (2) functional, and (3) economic. Physical obsolescence is the deterioration of building components such as paint, carpets or roofing. This deterioration may be partially curable. The tables on pages 43, 205 and 239 consider only typical physical obsolescence. Individual judgments will have to be made of functional and economic obsolescence. Functional obsolescence is due to a deficiency or inadequacy in some characteristic of the building, such as too few bathrooms for the number of bedrooms, or some excess, such as a 10 foot ceiling in a residence. This obsolescence may be curable. The tables do not include functional obsolescence considerations. Economic obsolescence is caused by factors not directly concerning the structure, but rather, by adverse environmental factors, resulting in loss of desirability. Examples include the obsolescence of a store in an area of declining economic activity, or obsolescence resulting from governmental regulation changing the zone of an area. Because this kind of obsolescence is particularly difficult to measure, it is not included in the tables. “Effective age” considers all forms of depreciation. It may be less than chronological age, if recently remodeled or improved, or more than the actual age, if deterioration is particularly bad. Though effective age is not considered in the physical life tables, it may yield a better picture of a structure's life than the actual physical age. Once the effective age is determined, considering physical, functional and economic deterioration, use the percent good tables on pages 40 or 200 to determine the present value of a depreciated building. Present value is the result of multiplying the replacement cost (found by using the cost tables) by the appropriate percent good. Limitations This manual will be a useful reference for anyone who has to develop budget estimates or replacement costs for buildings. Anyone familiar with construction estimating understands that even very competent estimators with complete working drawings, full specifications and precise labor and material costs can disagree on the cost of a building. Frequently exhaustive estimates for even relatively simple structures can vary 5% or more. The range of competitive bids on some building projects is as much as 10%. Estimating costs is not an exact science and there is room for legitimate disagreement on what the "right" cost is. This manual can not help you do in a few minutes what skilled estimators may not be able to do in several hours. This manual will help you determine a reasonable replacement or construction cost for most buildings. It is not intended as a substitute for judgment or as a replacement for sound professional practice, but should prove a valuable aid to developing an informed opinion of value.

Introduction | Table of Contents | Back Cover