Recommended: Adding a waterproof membrane and strengthening roof connections when replacing a roof. Adding collar ties and gable end bracing (see page 12). Bracing and securing chimneys. Maintaining roofs to lessen damage during a disaster.

Not Recommended: Not maintaining or repairing roofs as needed. Not strengthening materials and connections when possible. Allowing leaves and debris to build up on a roof or in gutters.

Standing seam metal roof. Image Credit: Patrick Sparks Engineering, Inc|Patrick Sparks

Standing seam metal roof. Image Credit: Patrick Sparks Engineering, Inc|Patrick Sparks

Corrugated metal roof in Shreveport, LA. Image Credit: NPS|Sarah Marie Jackson

Corrugated metal roof in Shreveport, LA. Image Credit: NPS|Sarah Marie Jackson

The best time to upgrade a roof is when it needs replacement. Use this opportunity to incorporate new storm-resistant materials, secure the roof decking, and strengthen the connections. All of these things offer additional protection from high winds. This is also a good time to add waterproof self-adhering membrane or “water shield” to the roof deck. Water shield membranes provides backup protection if shingles or other roofing materials are blown off by a storm. Wind-resistant shingles offer additional protection. The exterior roofing materials should always be replaced with in-kind materials unless there is a compelling reason to change them.

Terra Cotta roof at Kings Highway Christian Church in Shreveport, LA. Image Credit: NPS|Sarah Marie Jackson

Terra Cotta roof at Kings Highway Christian Church in Shreveport, LA. Image Credit: NPS|Sarah Marie Jackson

Slate roof at Marston House in Shreveport, LA. Image Credit: NPS|Sarah Marie Jackson

Slate roof at Marston House in Shreveport, LA. Image Credit: NPS|Sarah Marie Jackson

A roof that is nearing the end of its service life or that is not well maintained is more susceptible to damage from high winds. While replacing the roof may not be part of the plan, strengthening the connections between structural elements provides protection against wind uplift. Ensure that roofing and roof sheathing are well attached to the framing. Strengthening or replace roof vents. Making all necessary repairs to ensure the roof can resist high winds. Applying a construction adhesive along the roof deck and rafters connecting the pieces can strengthen the connections and does little to alter historic character.

For gabled roofs, gable ends are often the tallest walls on a house and are frequently improperly braced or connected to the building’s structure. These walls and roof edges are particularly susceptible to high winds. Adding gable end bracing prevents failure of the gable and securing the roof structure to the end wall prevents uplift. These retrofits can be easily and discretely accomplished from the attic space and should be a high priority.

Asbestos roof on an outbuilding in Campti, LA. Image Credit: NPS|Sarah Marie Jackson

Asbestos roof on an outbuilding in Campti, LA. Image Credit: NPS|Sarah Marie Jackson

Chimneys should be braced and securely attached to the building to reduce the risk of failure during a storm. High winds can topple a chimney, causing it to collapse onto the roof. Flooding can wash-out a chimney foundation. If a chimney falls, it could not only damage the building, but also surrounding buildings or landscape features. Chimneys must be braced if they are more than 2 1/2 times taller than they are wide. Metal strap bracing can be added to attach the chimney to structural elements such as ceiling or floor joists. If the mortar that holds the masonry together is weak or missing, it should be repointed to ensure stability.

Gable. Roof styles drafted by Cynthia J. Steward, LDHP..

Gable. Roof styles drafted by Cynthia J. Steward, LDHP.

Double Pitch Hip. Roof styles drafted by Cynthia J. Steward, LDHP.

Double Pitch Hip. Roof styles drafted by Cynthia J. Steward, LDHP.

Double Pitch Hip. Roof styles drafted by Cynthia J. Steward, LDHP.

Double Pitch Hip. Roof styles drafted by Cynthia J. Steward, LDHP.

Shed. Roof styles drafted by Cynthia J. Steward, LDHP.

Shed. Roof styles drafted by Cynthia J. Steward, LDHP.

Hip. Roof styles drafted by Cynthia J. Steward, LDHP.

Hip. Roof styles drafted by Cynthia J. Steward, LDHP.

Parapet. Roof styles drafted by Cynthia J. Steward, LDHP.

Parapet. Roof styles drafted by Cynthia J. Steward, LDHP.

Mansard. Roof styles drafted by Cynthia J. Steward, LDHP.

Mansard. Roof styles drafted by Cynthia J. Steward, LDHP.

Gambrel. Roof styles drafted by Cynthia J. Steward, LDHP.

Gambrel. Roof styles drafted by Cynthia J. Steward, LDHP.

 

 

 

 

References

Add Strength and Water Resistance When Repairing Your Roof, LSU AgCenter 

Against the Wind, FEMA

Disaster Mitigation for Historic Structures, 1000 Friends of Florida

Engineering Principles and Practices for Retrofitting Flood-Prone Residential Structures (Third Edition), FEMA

Homeowners Guide to Retrofitting: Six Ways to Protect Your Home from Flooding, FEMA

Additional Resources

Home Builders Guide to Coastal Construction: Technical Fact Sheet Series, FEMA


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National Center for Preservation Technology and Training
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