Masonry Magazine January 1975 Page.17
NCMA-TEK
An Information series from National Concrete Masonry Association
Cold Weather Construction With Concrete Masonry
71
Concrete Units
Introduction
Cold and other inclement weather (rain, snow, ince) cost many persons a considerable amount of money. Home buyers pay more for homes because builders work only a portion of the year, though overhead costs continue throughout the year. Taxpayers pay more when schools and other public buildings are not completed as fast as they can be. Building owners and businessmen lose money when they have to wait for new stores, offices, and factories to be completed. Skilled workers, such as bricklayers who average working only 35 weeks a year, lose wages because of bad weather shut downs. Several years ago, the U.S. Department of Commerce estimated that the nation's economy loses up to $10 billion annually as the construction industry slows down, and even shuts down, because of inclement weather.
The effects of seasonality on the construction process and the economy in general are well known. In most instances, the adverse effects can be overcome with the use of proven techniques and available materials. Experience in Canada, Northern Europe, as well as in several cities in the United States has demonstrated that all-weather construction is in expensive. A Canadian Construction Association survey has indicated that the additional cost of all-weather construction is between 3/4 of one percent and 1.5 percent of the total contract price. This added cost in most cases is easily offset by the economic benefits of early completion.
Recommendations for the construction of strong and durable masonry during cold weather have been developed by the International Masonry Industry All-Weather Council. This Council is composed of the following organizations: Bricklayers, Masons & Plasterers International Union of America; Laborers' International Union of North America; Mason Contractors Association of America; National Concrete Masonry Association; Portland Cement Association; and Brick Institute of America. The following discussion and recommendations are largely based on the booklet entitled "Recommended Practices and Guide Specifications for Cold Weather Masonry Construction," Copyright 1973 (Fourth printing, November 1974), published by the International Masonry All-Weather Council.
Weather Data
General
The designing, planning and execution of all-weather masonry construction projects require several types of weather service data. These data fall into two general categories: climatology, which may be defined as the historic record of the average and the extremes of atmospheric phenomena; and meteorology, which may be defined as the current state of the atmospheric conditions and their short-term projected movement and consequences.
The individual planning an all-weather masonry construction project is usually concerned with the average climatological data (i.e., average daytime and nighttime temperatures for the expected period of construction and the expected extremes for this period; and the average wind velocity and the expected extremes). From these data, he can make judgements as to the amount and type of protection, if any, that may be necessary, and base his planning and cost estimate accordingly. Generally, the contractor, who is responsible for the execution of the project, is more interested in the immediate and short-term meteorological conditions at the project site. For example, if the temperature is 37 F. at 3 P.M. at the site, he must know what the temperature, wind, etc., will be at 3 A.M. the following morning so he can plan and act accordingly.
Sources of Data
The major source for most weather data is the National Oceanic and Atmospheric Administration (NOAA), U.S. Department of Commerce. Climatological design and planning data are available from the Environmental Data Service of NOAA. Meteorological information for weather forecasting is available from the U.S. Weather Bureau of NOAA.
TEK 71 © 1975 National Concrete Masonry Association