A computer program has been developed to handle cost accounting and estimating for the project. This can be very useful for analyzing variations in the project, changes in costs of labor and/or materials, and for extension of the project to other areas.
The program does the following:
1) All costs are kept as lists of hours of labor for different types of work (eg. number of hours of carpentry labor, number of hours of unskilled labor, etc.), lists of materials (eg. Board Feet of Lumber, Number of roofing tiles, pounds of nails, etc.), lists of fuel consumption (gallons of gasoline, gallons of oil, KWH of electricity), lists of tools and equipment.
It is quite easy to substitute in different labor costs for another situation and get a new estimate. We actually did this with a local contractor, inserting his costs of labor and materials and calculating what he would have to charge to build the house as compared to what the cooperative could do it for.
Also note that materials are listed in the estimate in two ways. There is a section of the estimate showing the costs of producing locally the materials needed. This shows the number of hours of labor, materials (if any), tools , and fuel used in the production of the materials. By substituting in the costs of labor, fuel, etc. a local cost for production is computed. The program easily calculates the cost based either on local production of these materials or based on purchase on the local market.
2) A change in any of these costs can be given to the program and in about 3 seconds a complete new cost estimate can be made. Thus changes in labor rates due to inflation or type of workers used (eg. professional builders vs self-help) can be instantly incorporated. Or a change in lumber prices, cost of gasoline, or any other item used in the project can be quickly entered and the new cost estimate generated. In this way the overall estimate never becomes outdated by changes in labor or material costs.
3) The program allows changes in simple design parameters. For example, the size of certain rooms can be changed. The program will automatically calculate the new sizes of other rooms, new size of the house, amounts of various materials required including size and length of structural members. In several seconds a complete new estimate has been generated showing the amount of labor and materials required to build the revised plan along with the total cost based on the current prices of labor and materials.
4) Changes can also be made in structural variables. The design loads the building is designed to resist can be changed. Also spacing of rafters or posts can be altered. The program will make the necessary structural calculations to determine the size beams and rafters required. All this will then be incorporated into the list of materials and overall cost estimate.
The variables which may be easily altered are listed on the page titled "VARIABLES ESTRUCTURAL Y DE DISENO". A sample printout and estimate titled "COSTOS Y CANTIDADES" is attached. This estimate is based on the cooperative performing all its own labor, thus all labor is figured at a single rate. The coop pays its members C$400/day. We have used C$600/day (50% higher) so as to provide a high side estimate.
The chart titled "Precios Variables. Catalogo de Costos" gives a list of materials used in the construction and current prices. It also lists the wage rates for various types of labor. Changes in prices can be inserted here and they changes will be immediately reflected in the cost estimate for the housing.
Also listed here are costs of producing various materials with self-help labor. These costs will change principally as the labor rate allocated for self-help labor changes.
The chart entitled "Variables Estructural y de Diseņo" shows key variables in the design of the house. Any of these items may be changed and the change will be immediately reflected in the quantities of materials and labor in the estimate, sizes of structural members, etc. In addition various aspects of the house such as its floor area, area of walls, etc. are calculated and shown under "Dimenciones y Areas Resultantes". Measures shown in feet are also shown in meters
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