Your roof and storm damage prevention

9/24/2020 (Permalink)

Wind damage can be just as devastating as flood damage. Inspect your roof and use the best materials you can afford

Certain home shapes and roof types can better resist high winds and hurricanes, according to a researcher at New Jersey Institute of Technology (NJIT). Civil engineer Rima Taher, PhD, special lecturer in the New Jersey School of Architecture at NJIT. She spent two years examining the findings of research centers that have studied the best designs and construction materials and methods needed to withstand extreme wind events and hurricanes.

"Although I'd like to say that there is a simple and economical solution for housing that won't fail or collapse in the perfect storm, such information does not yet exist," said Taher. "However, it is obvious that thanks to the work of wind engineers and researchers that changes to home design and construction can make buildings safer for people, while saving government and industry billions of dollars annually."

"Design of Low-Rise Buildings for Extreme Wind Events" (Journal of Architectural Engineering, March, 2007) by Taher highlighted such research findings. Wind researchers at the Center for Building Science and Technology (CSTB) in France, researched and tested reduced-scale home models at its wind tunnel facilities, and developed a prototype of a "cyclonic" or hurricane-resistant dwelling. Taher cooperated with the CSTB wind researchers, working on the structural aspect of the home's design.

That design eventually became an elevated structure of a square plan form on an open foundation. The home had a hip roof and was equipped with a central shaft with aerodynamic features designed to reduce wind forces during an extreme wind event. Wind tunnel tests at CSTB showed that such a home would be far more efficient under high winds and hurricane conditions than a typical structure. CSTB is working with a builder to construct a prototype of such a home on Réunion in the West Indian Ocean.

From this work and other studies Taher recommends the following construction considerations for homeowners in hurricane-prone regions.

• A home with a square floor plan (or better a hexagonal or octagonal plan) with a multiple-panel roof (4 or more panels) was found to have reduced wind loads.
• Roofs with multiple slopes such as a hip roof (4 slopes) perform better under wind forces than gable roofs (2 slopes). Gable roofs are generally more common because they are cheaper to build. A 30-degree roof slope has the best results.

• Wind forces on a roof tend to be uplift forces. This explains why roofs are often blown off during an extreme wind event. Connecting roofs to walls matters. Stapled roofs were banned following Hurricane Andrew in Florida in 1993.
• Strong connections between the structure and its foundation and connections between walls are good. Structural failure is often progressive where the failure of one structural element triggers the failure of another, leading to a total collapse. Connections are generally vulnerable but can be inexpensively strengthened.
• Certain areas of a building such as the ridge of a roof, corners and eaves are normally subject to higher wind pressures. In the cyclonic home design, CSTB researchers proposed some aerodynamic features to alleviate these local pressures such as introducing a central shaft which would function by creating a connection between the internal space and the roof ridge considered to be the location of the largest depression. This connection helps balance pressures leading to a significant reduction in the roof's wind loads.
• Roof overhangs are subject to wind uplift forces which could trigger a roof failure. In the design of the hurricane-resistant home, the length of these overhangs should be limited to 20 inches.
• The design of the cyclonic home includes simple systems to reduce the local wind stresses at the roof's lower edges such as a notched frieze or a horizontal grid to be installed at the level of the gutters along the perimeter of the home.
• An elevated structure on an open foundation reduces the risk of damage from flooding and storm-driven water

Not only does the shape of the roof need to be taken into account but so to the material that it is made out of. We will also take a look at the roofing materials available along with the relative costs for them.

Asphalt Roll Roof

Asphalt roll roofing is made from large rolls of the same material used in asphalt shingles. Used for relatively flat pitches, such as angled shed roofs, roll roofing is installing by laying strips lengthwise across the roof in overlapping courses. Roll roofing is a fairly easy material to install, and many DIYers do this themselves. But it is better suited for sheds, garages, and perhaps porch roofs, and is not a very good solution for most home roofs.

Average Lifespan

Asphalt roll roofing can be expected to last from 5 to 10 years, at most. Getting maximum life from the roofing is really just a matter of keeping it clear of debris and quickly patching any punctures or damage that occurs.

Installation Costs and Lifetime Value

Asphalt roll roofing is normally installed on roofs with a relatively flat peak, so a 2,000 square foot house will have very close to 2,000 square feet of roof area. Average costs for installing this roof are about $2.25 per square foot, for a total average cost of roughly $4,500. But assuming that this roof will likely need to be replaced perhaps 12 times over 100 years, total costs over this period, in today's dollars, can be as high as $54,000 over 100 years.

Built-Up Roofing (BUR)

A built-up roof (BUR) is a layered roof that is created by alternating layers of roofing felt and waterproof materials such as fiberglass, and hot tar (bitumen). Normally used on roofs that are flat or with a very slight pitch, BUR roof. It is fire-resistant and inexpensive, but the roofing is messy and smelly to install.

Average Lifespan

BUR roofs typically last from 20 to 30 years. Maximizing the lifespan of a built-up roof is accomplished by regular inspection and repair, and by keeping debris off the roof to prevent degradation of the surface.

Installation Costs and Lifetime Value

Built-up roofing average about $4 per square foot, installed. On a 2,000 square foot house with a roof very close to that square footage, average professional installation costs about $8,000. Assuming that this roof will need to be replaced about four times over a 100 year period, average roofing costs in today's dollars are about $32,000 over 100 years. However, this type of roof is not suitable for a home with any real slope to the roof.

Composite Asphalt Shingle Roof

Composite shingle roofing is the most popular of all roofing materials, found on more than 80 percent of all homes. Composite shingles use either an organic or fiberglass base that is saturated with asphalt, coated on the bottom side with asphalt, and the exposed surface impregnated with small chips of slate, schist, quartz, or ceramic granules. The vast popularity of shingles owes to the relatively low cost, easy installation, and decent life expectancy. These roofs are normally installed by professional crews, but installation is not out of reach for a skilled DIYer.

Average Lifespan

Composite asphalt shingles can be expected to last 15 to 40 years, depending on the quality of the materials chosen. Some shingle roofs may even last as long as 50 years. Most shingle roofing manufactures offer a range of products in different weights and different life expectancies. Manufacturers like Owens Corning, GAF, or Certainteed come with accordingly high-end warranties pushing a half-century.

Maximize the lifespan of asphalt shingle roofs by avoiding cheap shingles and avoiding walking on them. Keep them free of moss, and never power wash an asphalt shingle roof.

Installation Costs and Lifetime Value

On average, asphalt shingle roofs cost around $5 per square foot to instal,l although the price range can be substantial, depending on the types of shingles selected and the labor costs from region to region. Assuming that a 2,000 square foot house with a typical roof slopes has a roof square footage of about 2,200 square feet, that roof averages about $11,000 for professional installation. Assuming this roof might be replaced three to four times, an asphalt shingle roof will cost, in today's dollars, $33,000 to $44,000 over 100 years. Since a typical homeowner rarely lives in a home for more than 30 or 40 years, during which they may reroof only once, asphalt shingles make for a fairly cost-effective roofing material from most people.

Wood Shingle Roof

Wood shingle roofs are made from thin, wedge-shaped pieces of natural wood, such as cedar or yellow pine, which are sawn from logs. They make for an extremely attractive roof but are tricky to install and not suitable for most DIYers. Be aware that growing fire hazards in some regions has caused legal restrictions on the use of wood roofing materials. They are not a good choice in any location where there are seasonal wildfire hazards.

Average Lifespan

Wood shingle roofs average about 25 to 30 years in longevity, though longer lifespans are sometimes achieved in locations where the roof experiences mild conditions and remains free of debris. Meticulously maintained, wood shingle roofs can last for 50 years. To extend the life of a wood shingle roof, make sure to replace split and cracked shingles immediately, and keep the roof free of moss.

Installation Costs and Lifetime Value

Wood shingles are more expensive than asphalt shingles, costing between $6.50 and $11.00 per square foot, installed. Assuming an average of about $9 per square foot, a 2,000 square foot house with 2,200 square foot of standard sloped roof will cost $19,800 to roof. Assuming this roof will need to be replaced at least three or four times over a century, costs can be as high as $60,000 to $80,000 over 100 years, calculated in today's dollars.

Wood Shake Shingle Roof

Wood shakes are a thicker material than wood shingles, and they can be expected to stand up better than wood shingles to weather and UV rays. They are not suitable for most DIYers to install, requiring professional installation. Like wood shingles, shakes may be restricted in regions where wildfires are a known hazard.

Average Lifespan

Wood shake roofs can be expected to last 35 to 40 years, though longer life is not rare. To maximize lifespan, you do need to baby them and practice proper maintenance. There is no "set it and forget it" option for any wood roofing material. Remove debris as soon as it falls on the roof. Eliminate moss. Replace split shakes right away. Replace curled, cupped, or split shakes immediately.

Installation Costs and Lifetime Value

Both the materials and installation are more expensive for shakes than for wood shingles. You can typically count on shakes being about 50 percent more expensive than shingles. Based on an assumption of $13 per square foot, a 2,000 square foot house with 2,200 in sloped roof square footage will cost $26,000 to install. If three installations are required over a century, average costs in today's dollars would run $78,000 over 100 years.

Standing-Seam Metal Roof

An increasingly popular type of roofing, especially in areas prone to wildfire danger, standing-seam metal roofs are made from large steel panels laid on the roof deck with the seams overlapping in raised ridges that run vertically along the roof slope. Metals used are usually steel or aluminum, although copper and zinc are also used. These roofs are virtually maintenance free, and very durable. They are not suitable for DIY installation, however.

Average Lifespan

Standing-seam metal roofs have a lifespan of 30 to 50 years, but as a relatively new product, information is still being gathered. In good circumstances, metal roofs may well last 75 years. To maximize lifespan, regularly check them to make sure that fasteners and sealants haven't failed, and inspect for distressed, bent, or slipped panels.

Installation Costs and Lifetime Value

Costs for standing-seam metal roofs average about $10 per square foot for steel or aluminum, $13 per square foot for zinc, and $18 per square foot for copper. For a 2,000 square foot house with 2,200 in sloped roof area, average national costs for a steel panel roof are about $22,000. But there is strong evidence that improved metal roofs now being sold may routinely last 50 years. If a metal roof is replaced only once, costs in today's dollars are $44,000 over 100 years.

Is Metal Roofing the Best Value?

For a homeowner who lives in a home for 30 to 40 years before selling, a single $22,000 re-roofing expense might be the only one ever incurred if using metal roofing. And if you are shopping for a new home, buying one with a metal roof may mean you'll never face a re-roofing project at all. In many ways, standing-seam metal roofs might be a more cost-effective option then the far more popular asphalt shingle roof.

Clay or Cement Tile Roofs

Clay tile roofs are very popular in the Southwest, but they can be found anywhere in the country, thanks to their incredible strength and durability. Traditional tiles are made from terracotta clay, but there are also ceramic tiles roofs (made of fired clay), as well as concrete tile roofs. All consist of individual tiles installed in overlapping layers over the roof surface, and all have roughly the same degree of strength and durability. They require a sturdy roofing framing sufficient to hold the weight and must be installed by skilled professionals. This may well be the only roof your home ever needs.

Average Lifespan

Clay tile roofs routinely last 100 years or more when properly maintained. Tile roofing's Achilles heel is not decay, as with wood shake or shingles, nor the slow sloughing off of mineral grains, as with composite shingles. Rather, cracking is what can doom tile roofs. Avoid walking on your tile roof as much as possible. When efflorescence develops, as often happens with terracotta, buff it off with a clean, dry towel. Coat the tiles with a clear alkyd primer. Replace cracked and broken tiles as soon as you spot them.

Installation Costs and Lifetime Value

Costs vary considerably, depending on whether the tiles are traditional clay terracotta, fired ceramic, or concrete. Concrete tiles can cost around $10 per square foot, installed; terra cotta can range from $15 to $20 per square foot installed; and ceramic tile, from $20 to $30 per square foot, installed. If installing a traditional Spanish clay tile roof at $20 per square foot, costs for a 2,000 square foot house with 2,200 of sloped roof area would be $44,400. However, since this roof will very likely last a century, costs in today's dollars would remain $44,000 over 100 years. If you are really concerned about future owners, a tile roof is a great choice. And if you are shopping for a new home, a tile roof less than 50 years old may well be a house you'll never need to reroof.

Slate Roof

Slate is another version of a stone roof, but rather than being made from molded clays or concrete, these are roofs covered with actual stone hewn from rock mined from quarries. Slate has a natural tendency to split into flat slabs, making this the ideal natural stone to cover roofs. Slate must be installed by trained craftsmen. It is the most expensive of common roofing materials, but also the most durable of all. Properly maintained, it can potentially last the lifetime of your home

even if that lifetime is two centuries long. Because of the expense, this is a roofing material usually used on large, luxury homes.

Average Lifespan

This is a roof that can easily last 100 years or and far more. There are slate roofs still in operation that literally date back to Shakespeare's time. To achieve this kind of longevity, immediately replace any broken slate tiles you see. Make sure that all flashings are correctly installed and in good working order. When your copper flashing has turned black, it is time to replace it.

Installation Costs and Lifetime Value

There is quite an enormous variation in costs for a slate roof, which can range from around $10 per square foot to as high as $75 per square foot, installed. Assuming an average installation cost of $30 per square foot, a 2,000 square foot home with 2,200 in sloped roof area can cost roughly $66,000 to roof with slate. That 's the only cost ever incurred though. Ever. At today's dollars, a slate roof would cost $66,000 over 100 years. And $66,000 for 200 years. And $66,000 for 300 years...

No matter what materials your roof is made out of, how new, or well maintained it is there will be times when the weather can cause damage to your roof and cause water damage to your home. It is important to check its condition often and repair damages immediately to avoid costly water damage repairs down the road.

Roofing materials article

https://www.thespruce.com/best-roofing-materials-for-longevity-1821951

Article by science daily.

https://www.sciencedaily.com/releases/2007/06/070619155735.htm

Photo: Boston Globe