• Concrete

Concrete can be very difficult to calculate, or it can be very easy. The best way to simplify things is to make a formula. For example, if all the concrete you pour needs to be 4", you need to figure out how much square feet of area a cubic yard of concrete will cover with 4 inches. So here is your formula:

1 cubic yard = 27 cubic feet = 46,656 cubic inches
1 square foot of concrete 4" thick = 576 cubic inches (12" x 12" x 4")
46,656 cubic inches / 576 cubic inches = 81 square feet of coverage

Once you figure out how much each cubic yard of concrete will cover, based on your specifications, you can divide the number of square feet you need by the number you derived to find out exactly how many cubic yards of concrete you need total. For instance, with the above calculation, if you need concrete for 1,200 sq. ft. you divide that by 81. 1200 sq ft. / 81 = 14.8 cubic yards of concrete.

To be on the save side you will probably want to add 5-10% waste factor. You want to do this in all the aspects of the construction cost estimations.

Also, you need concrete for your foundation, and most foundation contractors charge by the hour or by the square footage, so find out which to estimate your costs here.

• Footings
Again, as a general rule, a good foundation sub will want to give you these figures so he or she an get the work done without delays of problem. For the most part, footing contractors charge by labor only, and will charge by the lineal foot of footing poured. Pier holes will be extra, and you provide the concrete. A footing contractor will know the code requirements for your area, so you will calculate your expenses using those dimensions. You will want to come up with a simple formula like you did for concrete.

For example: If your footings need to support an 8" block wall
Footing dimensions = 8" high x 16" wide
8" x 16" x 12" (1 foot of footing) = 1,536 cu. in.
46,656 cu. in. / 1,536 cu. in. = 30.38 lineal feet of footing per cubic yard of concrete.
So, if you have a 1200 lineal ft. home you would divide 1200 by 30.38 to decide how many cubic yards of concrete you will need.
1200 lineal ft. / 30.38 lineal feet = 39.5 cubic yards of concrete (plus 10% for waste)

o Concrete Floors or Slabs: you will want to know the dimensions then calculate as shown above based on the dimensions needed.
o Monolithic Slabs: with monolithic slabs you will want to break one-piece slabs into two components--the slab and the footing section--then figure the items separately.
o Block Foundations and Crawl Spaces: concrete blocks usually come in 8" x 8"x 16", so when determining how many blocks you need, if you will be using this size of block you will measure the height of the wall in inches and divide by 8, this will tell you how many block you have in each row. Then you will figure out how many rows you need. Multiply the number of blocks in each row by the number of rows you need, and that will tell you how many blocks you need total.
o Poured Concrete Walls: usually the sub will charge by the lineal foot, and the price will include the concrete. If it doesn't you will have to figure the concrete separately.
o Brick: To figure the number of bricks needed, you want to figure out the square footage of the wall then multiply that by 6.75 (there are usually 675 bricks per 100 sq. ft. of wall). Of course, as with all of the others, add an extra 5-10% for waste.
o Mortar: You will probably need to figure one bag of mortar for every 125 bricks, and one bag of mortar for every 28 blocks. Also realize that each bag of mortar mix requires about 20 shovels full of sand, so calculate that cost as well. The mason you hire may supply the mortar, if not they will get you accurate take-offs of both the mortar and the bricks.
• Framing
Framing is the hardest part to estimate. You are going to really need to study the layout and construction techniques of your home carefully. You will want a scaled blueprint and a scaled ruler for measuring. You will probably want to consult with your framing contractor when you are estimating your framing costs, as they will help you know what you will need, how far apart your joists will be spaced, etc. Also, don't forget there is more to framing then just the walls, so consider all aspects of framing. Or, you can let your materials supplier do this--get 3 bids and check the supplies against each other. Also, you will want a good framing sub help you, and tell you what is good and what isn't because some lumber supply companies send out twisted or warped lumber, and have awful service. So, have a framing sub review everything, and also have them give you a count of nails that will be needed.
o Floor Framing
o Wall Framing
o Roof Framing
You can always send back lumber, nails, and other unused supplies. Sometimes you have to pay a 10% restocking fee, but this can be negotiated. So, in order to keep track of materials you want to return, keep them in a neat, separate stack.

• Roofing Shingles
Roofing shingles are sold in "squares." A "square" is the number of shingles you need to cover 100 sq. ft. of roof. So, in order to estimate the cost of roofing shingles you will need to find the square footage of the roof, and add 1 ½ sq feet for every lineal foot of eaves, ridge, hip, and valley. Then, of course you want to divide the total you come up with by 100 to know how many "squares" you will need. However, shingles aren't your only cost. You will probably need roofing felt as well. It comes in 500 sq. ft. rolls. So, divide the sq. ft. of the roof by 500 and add 20% for overlap and waste to determine the number of rolls you will need. You may also need flashing, as it is required around chimneys and areas where two rooflines of differing heights meet. This comes in 50 ft rolls, so you will need to figure out how much you need. You can get deadly accurate take-offs on roofing materials by asking a roofer to figure the numbers.

• Siding and Sheathing
Multiply the perimeter of the outside walls by the height to obtain the total square footage of the outside walls. Now, if there is any other part of the house that needs siding or sheathing find the square footage of that as well. Depending on the siding you use and how it comes will determine how much you need to buy, just make sure you have enough to cover all the square feet you have to cover. A sider will give you the take-off to compare with the supplier (lumberyard, siding supplier, etc.) You may get a better deal straight from a supplier, you may get a better one through a sider.

• Cornice Material
To estimate cornice material you need to know the type and style and trim material you are going to use. Most cornice's require the following materials, so figure them into your costs as well (if you get these numbers from a sider or supplier they will figure these needed materials in):
o Fascia boards
o Drip Mold
o Soffit
o Bed Mold
o Frieze Mold

• Insulation
This is one of the easiest things to calculate. You simply multiply the perimeter of the area needing insulation by the height, and that will give you the square footage to be insulated and since insulation comes in batts and is sold in square footage coverage, you can get just what you need. However, insulation subs usually supply the insulation with their bid. It is usually much cheaper for them to supply the insulation, so the labor becomes cheap in comparison to what it costs you for the materials.

• Drywall
Drywall is usually sold by the sheet but estimated by the square foot. So find the square feet needing drywall, don't forget to count each inside wall twice, and count the space for openings, plus add some for waste. This should be a good estimate of what you need. If the house has vaulted or tray ceilings they will require extra wallboard and labor and that too should be added in. Also, for every 1000 sq. ft. of drywall figure on one roll of joint tape and 30 gallons of joint compound. Yada yada yada--you will be better off generally to pay supplier for materials. Make sure you get their figures for the lineal feet.

• Millwork and Trimwork
Basically the same lineal feet of walls used to calculate the drywall will tell you how many lineal feet of baseboard trim you will need. Add 10% for waste. Also, measure the perimeters of rooms that need crown or shoe molding, and add 10% for waste. So finish carpenters will do this, but not all of them, so you will want to get the estimates from drywall to check the lumberyards take-off figures.

• Flooring
Basically you are going to be using several different mediums of flooring (carpet, tile, linoleum etc.) so it is probably going to require the flooring contractor to come up with the cost estimate for your floors. You can however estimate by square feet plus 10% for waste. Flooring subs will give you figures which you should check against supplier figures.

• Miscellaneous Coverings
Miscellaneous coverings are things like slate for foyers or fireplaces, etc. All of these items are sold by the square footage of the area being covered, and subs usually charge their amount based on the same thing. So, talk to your subs, and figure the square footage to get a good cost estimate.

• Paint
The cost of paint is generally included in whatever big a painting contactor gives you, unless you specify otherwise. Most owner-builders choose to cut costs by doing some of the painting themselves, so to estimate your costs here, you will need to decide the amount of paint needed. Coverage is usually listed on the paint container, so figure out the square footage needing paint, and add 15% for waste and touch ups. If you paint yourself, you will want to learn how to use a power spray painter. They are not hard to use, but you want to make sure you are safe. To learn, ask the paint supplier for assistance, they will probably teach you how to use one for free. Then, you can rent the power spray painter from a supplier. Also, consider primer, and the amount you will need. You won't necessarily need primer for the outside, but it is a must on the inside with sheetrock. Consider getting extra paint for later touch ups, especially if you are having the colors custom mixed.

• Cabinets
Usually for cabinets you have the same person for your supplier and sub, but if you use a separate supplier and sub, have the sub check figures and layout. The plan for cabinets should be on your blueprint, so use that layout if you are buying the cabinets to estimate cost, and if you are having them installed by a contactor he or she will take care of the exact measurements. Just make sure that the painting, staining, and installation are all included in your cost estimate.

• Wallpaper
Typically one roll of wallpaper will safely cover 30 sq. ft. of wall area, including matching patterns and waste. So, determine the amount of area needed to be covered and divide by 30 to figure the number of rolls needed. I personally dislike installing this myself, so I always sub this out. However, you really need to look around, the experience and price really vary.

• Misc.
You will need to calculate any windows, lights, hardware etc. you will need. These are pretty easy to calculate. You will want to check the window list twice or more before you sent out to bid, make sure you got it right. Also, with doors count and make sure your estimation is accurate.

Other estimates you will need, such as electrical, plumbing, heating, and air should come straight from the contractors themselves as they usually provide all the materials and labor.

• Buying or Renting Tools
One item you may overlook, but that you should figure into your cost estimation is the cost of the tools you will need. Any jobs you do yourself you will need tools for. If you hire a sub or a contractor they should have their own tools, but this is not always the case. So, leave some room in your budget, and cost estimation for the building tools you will need.