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Roofs
Roofs are a very important part of your home and yet, quite often they are selected by the architect with little input from the homeowner.
Your roof protects your house from the elements and the sun which can get harsh here in the Lowcountry. It must also stand up to the occasional hurricane.
The first thing to consider about your roof is the thickness and composition of your roof sheathing. This is the panel which is nailed to the rafters. The current building code (table R503.2.1.1(1)) requires these panels to be 7/16" thick (nominally) for rafters every 16". Many architects call out and builders use 1/2" (nominal) panels. At Willis Sinclair Homes, we always use 5/8" (nominal) panels on the roof. That is 43% thicker than the minimum required and 25% thicker than is normally called out.
The two common materials are plywood and OSB. While some argue both materials are about equal, there are some significant differences. One original problem with OSB was moisture soaking in the edges and making the board swell. Manufacturers now coat the edges, but in the real world, boards are cut in the field. Those edges will swell. OSB is not allowed on roofs in Dade County, Florida and yet OSB continues to be popular. One reason might be cost. Typically, OSB is less expensive than plywood. At Ponds & Sons, we use only plywood on our homes.
If you make sure you have 5/8" plywood on your roof, the next thing to consider is the plywood covering. Felt paper ("tar paper") is the old stand by covering, but it is woefully inadequate to protect against water intrusion. Felt paper also will not last very long in the hot sun before it deteriorates. That means the roofers have to be on the job within a very few days of the felt paper placement. Willis Sinclair Homes uses a product called "Ice & Water Shield" or something similar. This is a thick bitimous under layment that has adhesive on the back side so it adheres to the roof. It is a rubbery material, so it actually seals around nails and screws. It will completely waterproof the roof so the need to get roofers started in a few days is not so critical. Why is felt paper still used if Ice & Water Shield is so much better? Cost and ease of installation are the two main reasons. Ice and Water Shield is an excellent second line of defense in case of heavy winds and blowing rain.
Once the sheathing is on and covered, the next question becomes, "What type of roofing material should I use?" Here in the Lowcountry, the two most popular are architectural shingles and metal roofs. Slate and tile roofs are not often used.
By far, the lowest cost roof is three tab shingles. However, we prefer to use the next step up, architectural shingles. These are thick, multi layer shingles that look similar to the old three tab shingles except for the thickness. You can get them with several guarantees from twenty-five to fifty years. Strangely enough, shingles do not usually last for their warranty period. They typically cost about $1.50 per square foot for good architectural shingles. Shingles are on many roofs in the Lowcountry.
The next step up is a painted galvalum roof. This is a steel roof with a coating of aluminum and zinc. The galvalum coating is better than the old zinc (galvanized) coatings used in the past. One drawback of steel roofs is warranties. Typically, warranties will not be honored if the roof is within five miles of salt water. Many different colors are available. The colors are baked on, so repainting is very seldom needed.
| Roof type | Cost per square foot | Expected Lifetime |
| Architectural Shingles | $1.50 | 20-25 yrs |
| Painted Galvalum Steel | $6.00 | 40 yrs |
| Painted Aluminum | $6.50 | 40 yrs |
| Copper | $8.25 | 100 yrs |
Aluminum roofs are warrantied in areas close to salt water. They are also painted in many different colors. Some claim an aluminum roof is more likely to be punctured by a flying limb or debris in a storm than a steel roof. In reality, if things are flying around, damage is possible no matter what material is used.
Copper is another choice for roofing materials. The main appeals of copper are its appearance and extremely long life. Many of the very early buildings in our country which are still standing had copper roofs. Copper has been used for over a thousand years as a roofing material.
If metal is chosen, there is yet another decision to be made: the shape of the metal. Standing seam with hidden fasteners is the most popular. These panels are flat with a vertical rib on either side. Fasteners hold the rib down and the next piece of roofing covers the fasteners and snaps down. Hiding the fasteners is nice from an appearance view point as well as making the roof totally watertight. Some homes use corrugated roofing.
| Standing Seam | Corrugated |
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There are many other shapes. Some imitate slate or clay tiles. Which is best? Standing seam is very good because its fasteners are hidden and out of the weather. Corrugated has to be held down with screws which pierce the material. Although the hold down screws have rubber washers, anytime you pierce the roof, there is a potential for a leak.
At Willis Sinclair Homes, the most common roof we install is a standing seam roof. Typically, the seams are 17" apart to maximize the material usage (and thus minimize the cost).
If you are still wondering what sort of roof to use, give us a call. We can help you decide. We very much want you to have the best possible house for the best possible price.
Call (843) 846 - 2500