Putting up a new roof can cost as much as 2% to 3% of the total house cost, if high quality materials are used.
The three most basic needs of man are food, clothing, and a roof over his head. The importance of the third one should never be underestimated. Putting on a new roof or replacing the existing one is a huge improvement job. The cost estimates are dependent on a range of factors including location, material, roof size, and labor charges. To make an accurate estimate, you will need an accurate measure of the area or square footage of the house. Here, we provide a brief guide to calculating the same, along with rough estimates of the costs, according to the material used.
Let's compare prices per sq. ft. for different roofing materials. This will give you an idea about the variation of the cost, according to the material used. The costs compared here are rough estimates, which can vary with location, quality and type of the shingles, number of layers, slope, labor charges, and area of the roof. Know that it is not possible to provide exact estimates due to the high number of variables involved, and the estimate provided below are therefore, necessarily ballpark figures.
This is the cheapest of all the roofing materials, compared to all other options. Some of the best shingles in this category are provided by manufacturers like Owens Corning, GAF, and Certain Teed. They may be used to install a completely new roof or can be used to patch over an old one. They come in two types, which are fiberglass and organic. The average cost of this type of roofing is USD 0.8 to USD 1.2 per square foot. For a roof with a low slope, with a size ranging from 1650 to 2100 square feet, the total cost can range from USD 670 to USD 3700. The determining factor of the cost is the quality of materials used.
Wood shingle roofing makes for a pretty picture. However, it requires a lot of maintenance, costs more, and has an average lifespan of about 20 years. The average cost per square foot, for wooden shingles is USD 4 to USD 7. The cost to put it up, over a single story ranch home, with a roof area of about 1,600 to 2,100 square feet, will range from USD 6,800 to USD 14,700, with the exact cost dependent on the wood quality used.
Tile roofing is also a good choice of material, as it is durable, stylish, and rot-proof. The cost per square foot for a concrete tiles of standard quality will be about USD 4.50 to USD 9, which will rise to about USD 7 to USD 10 for the deluxe variety. Opting for the standard type, the costs for a basic one story, ranch style home roof (1,600-2,100 square feet) would be USD 7,600 to USD 19,000.
The advantage of having a metal roofing material is that it is lightweight, rot-proof, and fire resistant. For a single story ranch home (1,600-2,100 square feet), steel shingles costing USD 3 to USD 7.5 per square foot, will cost about USD 4800 to USD 16500 in total. For the same roof, coated-steel sheets will cost about USD 7 to USD 10, amounting to USD 11,200 to USD 22,000 for the roof.
Another option is going for interlocking aluminum shingles, that will cost about USD 7 to USD 9 per square foot or aluminum roofing panels that cost about USD 9 to USD 11 per square foot. The costliest option is copper, with rates ranging from USD 15 to USD 18 per square foot.
A slate roof is one of the long-lasting variety of materials, that you could use. Once installed, it lasts for a lifetime and hence, it costs substantially more than what other roofs would cost. The rate can range from USD 9 to USD 40 per square foot. A 1600 to 2100 sq.ft. roof will cost about USD 16,000 to USD 84,000.
Other than the material costs, the total cost will depend on the shape and size of your roof, of course. There may be some additional costs, if the roof supports of your house need some repairing, rebuilding, or reinforcement. This, along with labor costs, can make the additional costs go up to USD 1,000 to USD 10,000.
It is good that you show the willingness to make calculations and estimate the exact prices on your own. This is better than blindly paying the contractor, whatever he asks for. When you calculate costs on your own, you can get the roofing job done, at a reasonable price.
Method of Calculation
There is a method of calculating roofing estimates, which is discussed further. It is based on using the square footage of your home and roof pitch. For making calculations simpler, it is suggested that you keep the floor plan of your house, made to scale, designed by your architect, in front of you. This calculation assumes that your house has a gable roof.
In this method, you need to first calculate the pitch of the roof. Pitch measures how much your roof rises vertically, for each horizontal foot rise. One can do that with the following procedure. On the gable side of your roof, mark a spot at a distance of one foot horizontally, from roof base. Then, from the same spot, measure the distance, vertically, to the underside of the roof base. What you get is a right-angled triangle, with the distance from the underside of the roof as one side, the distance from the roof base as the triangle base (12" or 1 foot in length), and a part of one side of the gable roof as a hypotenuse.
Next, take the ratio of the distance, from the underside of the gable roof and the base length (12"). Let's suppose that the vertical distance from underside of the roof is 9". Then, the ratio is 9/12, which is 0.75. Next, square the ratio and add one to it. Then, our hypothetical ratio value will become (0.752 +1), which is equal to 1.5625. Lastly, find the square root of this number. In our case, square root of 1.5625 is 1.25. Since the gable roof extends a bit over the edge frame of the house, round off the number to the nearest decimal place. In our case, it rounds up to '1.3'. Remember this last number.
Take the last number (1.3) and multiply it by the total estimated square footage of your house. That is, if the total square footage of your house is 1200 sq.ft., then you must get (1200 x 1.3 equal to) 1560 square feet. Finally, multiply the last number (1560 here), by the roofing costs per square foot. If it is, say USD 1.2 per square foot, then the final roofing cost estimate will be (1560 x USD 1.2), which is equal to USD 1872. Though the calculations seem complicated, once you understand them, you can make an estimate in about a minute, using a calculator. If your house has a flat roof, simply multiply the total square footage, with the roofing cost per square foot, to get a rough estimate.
Going for an inexpensive roof with low quality materials may seem like a wise cost-saving measure right now, but it may cost more through repairs, in the long run. Opt for a high quality roof, that provides longevity and doesn't compromise on the aesthetic appeal.