The simpler the roof shape, the less costly it is to build. Plan
In another post I discussed how to use smart planning to save money during the rough framing stage of building. Once you have framed and sheathed the home, it's time to "dry-in", in other words, to finish the exterior envelope to the point that when it rains outside, it no longer rains inside the house, i.e adding the roof. When it comes to controlling roofing costs, there are two main topics to consider: the type of roofing material and the design of the roof.
The least expensive roof is going to be the simplest design. A flat roof that covers the whole house, a shed roof and a gable are all simple styles with a minimum of different planes. Once you start putting in dormer windows, skylights, and combining different roof planes that intersect you are increasing the cost. Of course these are also the factors that make a home architecturally interesting.
So what else should you consider? Every time the roof comes to an edge, whether at the end of the roof or a change in plane, for instance where the roof meets a chimney, metal flashing will need to be installed. These are critical points for possible leaks, so great care needs to be taken to detail these areas properly. More points that need to be flashed means higher roofing costs. Every penetration in the roof will also need to be flashed. Minimize chimneys, vents and other penetrations and you have a roof that will be less likely to leak in the future and less expensive to build and maintain.
The most common roofing material is the asphalt shingle. This is an affordable option, and just like tires tell you the mileage to expect, shingles will tell you the years to expect the roof to last. You get what you pay for, and if you are planning your forever house, it may pay in the long run to purchase a more expensive shingle so that you aren't paying for the labor to replace it again in 15 years.
If you want your roof to last even longer, there are higher-end options like metal roofing, slate or slate look-a-likes made from recycled tires. The flashing and gutters on your roof will last as long as a shingle roof or longer if you use the affordable painted aluminum. If you want gutters and flashing that will last forever, choose copper, but expect to pay a premium. If you have a flat roof, you will choose between modified bitumen, EPDM or TPO. Often these roll roofing products are called "rubber roofs". All of these products hold up well if installed properly, and can last indefinitely if coated every 5-10 years, an inexpensive maintenance when compared to replacing a roof.
In the past I've written about the benefits of mature trees around your home. The roof is another part of the house that can benefit from the shade provided by trees. Sun is the enemy of your roof, so if it is shaded, it will last longer. Keep your gutters free of leaves and you are set.
Of course if you really want to protect your roof, cover it in soil and plant sedums and grasses on top of your house. You will need to ensure that the roof framing is engineered to support the increased loads resulting from this wet soil. If you are building new, this is not difficult to do - talk to a structural engineer to be sure. A green roof not only absorbs rainfall and insulates the house, it also protects the roofing material underneath by shading it from the sun. Make sure the roof fits the home and your budget and you will rest easy when the first storm rolls in.
To see all Kenny Gronos' articles on Controlling Costs, click here
To see the house shown above, click Plan 48-237.