Importance of Tying Down Your Roof
By: Amanda Campbell
Updated: August 30, 2010
If you've seen any news footage of tornadoes or hurricanes, you've probably seen how easily their storm-force winds can pry a roof off a house. The roof is the most vulnerable part of your house. And if the roof blows off your house, it is easy for other parts of the house to collapse.
In order to protect your home and family, make sure your home is properly braced. Often builders simply "toenail" rafters into the top plate of the house's top wall. This means a long nail is hammered at a side angle through the rafter and into the top plate. In a heavy storm, wind can circulate under the roof's overhang, crack the rafter, rip out the toenails, and blow the roof right off. And if the roof is torn off, the rest of the house is vulnerable to severe damage.
Insist that your builder secure your roof with rafter clips. Also known as tornado clips or hurricane clips, rafter clips should be mounted to the top plate of the exterior wall and into each rafter. With rafter clips in place, wind should have to shear through the nails that attach the clips before it could rip off the roof.
In addition to rafter clips, every exterior corner of your home should be reinforced with 4'x8' sheets of Oriented Strand Board (OSB). Each sheet of OSB is nailed to the top and bottom plate of the wall, as well as to the entire length of the wall studs. This extra reinforcement at the corners will prevent the top plate of the exterior wall from blowing off if the roof should be lost.
Also, pay special attention to the way the walls of your home are attached to the foundation. Many builders simply nail the bottom of the wall into the concrete foundation. But to better secure the walls to the foundation, L-shaped bolts should be inserted into the concrete foundation immediately after it has been poured. Once the foundation has cured, the L-shaped bolts are permanently embedded. When the walls are framed, holes are drilled so the wall can be set down over the bolts then attached with a washer and nut to secure the wall.
Rafter clips, reinforced exterior corners, and L-shaped foundation bolts are three "must-haves" that will help your home stand strong in the face of dangerous storms, protecting your family and your belongings.
How tornado-resistant is your house?
How would your home fare against a tornado? Here's a short quiz. Add up your points, then match them to the H-scale (for home survivability) that appears at the end.
NOTE: This quiz is designed only to give you a rough indication of how tornado-resistant your home is. Don't use it to justify moving out of your neighborhood, suing your builder, or any other rash course of action!
1. What kind of home do you live in?
* Mobile (-10)
* Old building, light framing, not built to code (0)
* Newer building, reasonably well constructed (+10)
* Sturdy, well-built structure (+20)
2. (Non-mobile home) What kind of roof does your home have?
* Mansard (+3)
* Hip (+3)
* Gable (0)
* Flat (0)
3. (Non-mobile home) Do you have any of the following features?
* Attached garage facing south or west (-3)
* A cellar (+5)
* Porch facing south or west (-3)
* Large overhanging eaves facing south or west (-3)
4. How many trees do you have shielding your home to the south and west?
* None (0)
* A few (+1)
* A moderate amount (+2)
* Very many (+3)
5. Where do you live?
* On flat terrain (0)
* Next to a river (0)
* In a valley (0)
* Behind a magic tornado-proof hill blessed by four Indian tribes (0)
* On a hill (0)
* Other (0)
6. (Non-mobile home) If you are sure that the walls of your home have been securely anchored to the foundation (NOTE: sometimes builders, either to save time or money, will overlook this important step), add 10 points.
7. (Non-mobile home) If you have taken extra measures to ensure the roof is anchored well, give yourself five points if you have used extra nails to hold the rafters to the walls. Give yourself ten points if you have used a stronger connector, such as hurricane clips or anchor bolts.
8. (Mobile home) If you have tie-down straps anchoring your home, give yourself 3 points.
Point Totals
Less than zero: H0. Box kite. Tie a string to it.
1-10: H1. Straw house. Cross your fingers.
11-20: H2. Typical dwelling. Needs some work.
21-30: H3. Suburban special. Tough enough? Maybe.
31-40: H4. Storm shelter. Any room for the neighbors?
41-up: H5. Fort Knox. Blow wind, blow!
In order to protect your home and family, make sure your home is properly braced. Often builders simply "toenail" rafters into the top plate of the house's top wall. This means a long nail is hammered at a side angle through the rafter and into the top plate. In a heavy storm, wind can circulate under the roof's overhang, crack the rafter, rip out the toenails, and blow the roof right off. And if the roof is torn off, the rest of the house is vulnerable to severe damage.
Insist that your builder secure your roof with rafter clips. Also known as tornado clips or hurricane clips, rafter clips should be mounted to the top plate of the exterior wall and into each rafter. With rafter clips in place, wind should have to shear through the nails that attach the clips before it could rip off the roof.
In addition to rafter clips, every exterior corner of your home should be reinforced with 4'x8' sheets of Oriented Strand Board (OSB). Each sheet of OSB is nailed to the top and bottom plate of the wall, as well as to the entire length of the wall studs. This extra reinforcement at the corners will prevent the top plate of the exterior wall from blowing off if the roof should be lost.
Also, pay special attention to the way the walls of your home are attached to the foundation. Many builders simply nail the bottom of the wall into the concrete foundation. But to better secure the walls to the foundation, L-shaped bolts should be inserted into the concrete foundation immediately after it has been poured. Once the foundation has cured, the L-shaped bolts are permanently embedded. When the walls are framed, holes are drilled so the wall can be set down over the bolts then attached with a washer and nut to secure the wall.
Rafter clips, reinforced exterior corners, and L-shaped foundation bolts are three "must-haves" that will help your home stand strong in the face of dangerous storms, protecting your family and your belongings.
How tornado-resistant is your house?
How would your home fare against a tornado? Here's a short quiz. Add up your points, then match them to the H-scale (for home survivability) that appears at the end.
NOTE: This quiz is designed only to give you a rough indication of how tornado-resistant your home is. Don't use it to justify moving out of your neighborhood, suing your builder, or any other rash course of action!
1. What kind of home do you live in?
* Mobile (-10)
* Old building, light framing, not built to code (0)
* Newer building, reasonably well constructed (+10)
* Sturdy, well-built structure (+20)
2. (Non-mobile home) What kind of roof does your home have?
* Mansard (+3)
* Hip (+3)
* Gable (0)
* Flat (0)
3. (Non-mobile home) Do you have any of the following features?
* Attached garage facing south or west (-3)
* A cellar (+5)
* Porch facing south or west (-3)
* Large overhanging eaves facing south or west (-3)
4. How many trees do you have shielding your home to the south and west?
* None (0)
* A few (+1)
* A moderate amount (+2)
* Very many (+3)
5. Where do you live?
* On flat terrain (0)
* Next to a river (0)
* In a valley (0)
* Behind a magic tornado-proof hill blessed by four Indian tribes (0)
* On a hill (0)
* Other (0)
6. (Non-mobile home) If you are sure that the walls of your home have been securely anchored to the foundation (NOTE: sometimes builders, either to save time or money, will overlook this important step), add 10 points.
7. (Non-mobile home) If you have taken extra measures to ensure the roof is anchored well, give yourself five points if you have used extra nails to hold the rafters to the walls. Give yourself ten points if you have used a stronger connector, such as hurricane clips or anchor bolts.
8. (Mobile home) If you have tie-down straps anchoring your home, give yourself 3 points.
Point Totals
Less than zero: H0. Box kite. Tie a string to it.
1-10: H1. Straw house. Cross your fingers.
11-20: H2. Typical dwelling. Needs some work.
21-30: H3. Suburban special. Tough enough? Maybe.
31-40: H4. Storm shelter. Any room for the neighbors?
41-up: H5. Fort Knox. Blow wind, blow!
