How to Create a Room Addition Cost Spreadsheet

Room additions are often quite costly, because the construction has to provide its function as well as match the rest of the house structurally as well as aesthetically. In order to budget properly for a room addition it is important to get the contractors to break down the projected expenses, rather than simply supplying you with a per-square-foot charge; this way you can make an informed judgment when choosing a contractor. Making a cost spreadsheet to give to contractors to fill out will not only get you the information you need but also sends a signal to the contractors that you are to be taken seriously as a customer.

Spreadsheet program

Instructions

- 1
  Open a new spread sheet document and title it "Room Addition Cost Estimates" or something equivalent.
- 2
  Type "Labor" in cell A1. Type "Design" and "Construction" in cells A2 and A3, respectively. Type "Per Hour" in cell B1 and "Total Estimate" in cell C1. Type "Labor Total" into D3 then in E3 type the formula "=SUM(C2:C3)" so that E3 shows the total of the amounts entered into the spreadsheet by the contractor for the estimate of labor costs.
- 3
  Type "Materials" in cell A5 then "Per Piece" and "Total Estimate" into cells B5 and C5 respectively. Make a list from A6 down of materials that may be used, such as lumber, steel, concrete, glass, and hardware like nails and screws, bolts or hinges. The contractor will enter the amounts for each; expect a slight premium on hardware and the like because the time it takes for the contractor to purchase these items will be added to the overall price. Type three or four cells with "Misc 1" "Misc 2" in them for the contractor to add in any materials you missed.
- 4
  Type "Materials Total" in the last row items in column D, for example in D15 if you have nine items listed. In the E cell alongside the D cell type the formula "=SUM(C#:C#:C#)" where "#" represent the numbers of the C cells in the list. Include as many C cell numbers as have materials items listed for them. This will give the total of the materials estimate costs.
- 5
  Leave a blank row then type "Machinery Hire" in the A column, "Per Piece" in the B column and "Total Estimate" in the C column. In column A type in the names of machinery hire that may be required, such as diggers, concrete mixer's or pressure air tanks with a couple of miscellaneous columns as well. In the D column of the last row used type "Total Machinery Hire" then in the adjacent E column type in the formula "=SUM(C#:C#:C#:)" where "#" represents the appropriate row numbers. Include as many C cell numbers as are machinery hire items. This adds the total machinery hire.
- 6
  Type in "Total Room Addition Estimate" into the D cell one below the "Total Machinery Hire" cell. In the E cell adjacent type in "=SUM(E#:E#:E#)" where the "#" represents the E cells which contain the other subtotals of the different categories. This will give you the total estimate for the room addition. Save the spreadsheet and give a copy to each contractor you are considering for them to fill out and return to you with their bid.

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