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Tile Roofing for High-Wind Areas
Home Builder’s Guide to Coastal Construction

FEMA 499/June 2005
Technical Fact Sheet No. 21

Purpose: To provide recommended practices for designing and installing extruded
concrete and clay tiles that will enhance wind resistance in high-wind areas.

Key Issues

Missiles: Tile roofs are very vulnerable to breakage from windborne debris
(missiles). Even when well attached, they can be easily broken by missiles. If a
tile is broken, debris from a single tile can impact other tiles on the roof,
which can lead to a progressive cascading failure. In addition, tile missiles
can be blown a considerable distance, and a substantial number have sufficient
energy to penetrate shutters and glazing, and potentially cause injury. In
hurricane-prone regions where the basic wind speed is equal to or greater than
110 mph (3-second peak gust), the windborne debris issue is of greater concern
than in lower-wind-speed regions. Note: There are currently no testing standards
requiring roof tile systems to be debris impact resistant.

Attachment methods: Storm damage investigations have revealed performance
problems with mortar-set, mechanical (screws or nails and supplementary clips
when necessary), and foam-adhesive (adhesive-set) attachment methods. In many
instances, the damage was due to poor installation. Investigations revealed that
the mortar-set attachment method is typically much more susceptible to damage
than are the other attachment methods. Therefore, in lieu of mortar-set, the
mechanical or foam-adhesive attachment methods in accordance with this fact
sheet are recommended.

To ensure high-quality installation, licensed contractors should be retained.
This will help ensure proper permits are filed and local building code
requirements are met. For foam-adhesive systems, it is highly recommended that
installers be trained and certified by the foam manufacturer.

Uplift loads and resistance: Calculate uplift loads and resistance in accordance
with the Design and Construction Guidance section below. Load and resistance
calculations should be performed by a qualified person (i.e., someone who is
familiar with the calculation procedures and code requirements).

Corner and perimeter enhancements: Uplift loads are greatest in corners,
followed by the perimeter, and then the field of the roof (see Figure 1 on page
2). However, for simplicity of application on smaller roof areas (e.g., most
residences and smaller commercial buildings), use the attachment designed for
the corner area throughout the entire roof area.

Hips and ridges: Storm damage investigations have revealed that hip and ridge
tiles attached with mortar are very susceptible to blow-off. Refer to the
attachment guidance below for improved attachment methodology.

Quality control: During roof installation, installers should implement a quality
control program in accordance with the Quality Control section on page 3 of this
fact sheet.

Classification of Buildings
Category I: Buildings that represent a low hazard to human life in the event
of a failure
Category II: All other buildings not in Categories I, III, and IV
Category III: Buildings that represent a substantial hazard to human life
Category IV: Essential facilities

Design and Construction Guidance

1. Uplift Loads
In Florida, calculate loads and pressures on tiles in accordance with the
current edition of the Florida Building Code (Section 1606.3.3). In other
states, calculate loads in accordance with the current edition of the
International Building Code (Section 1609.7.3).

As an alternative to calculating loads, design uplift pressures for the corner
zones of Category II buildings are provided in tabular form in the Addendum to
the Third Edition of the Concrete and Clay Roof Tile Installation Manual (see
Tables 6, 6A, 7, and 7A). (see footnote)

Note: In addition to the tables referenced above, the Concrete and Clay Roof Tile
Installation Manual contains other useful information pertaining to tile roofs.
Accordingly, it is recommended that designers and installers of tile obtain a copy
of the manual and its Addendum. Hence, the tables are not incorporated in this fact
sheet.

2. Uplift Resistance
For mechanical attachment, the Concrete and Clay Roof Tile Installation Manual
provides uplift resistance data for different types and numbers of fasteners and
different deck thicknesses. For foam-adhesive-set systems, the Manual refers to
the foam-adhesive manufacturers for uplift resistance data. Further, to improve
performance where the basic wind speed is equal to or greater than 110 mph, it
is recommended that a clip be installed on each tile in the first row of tiles
at the eave for both mechanically attached and foam-adhesive systems.

For tiles mechanically attached to battens, it is recommended that the tile
fasteners be of sufficient length to penetrate the underside of the sheathing by
¼ inch minimum. For tiles mechanically attached to counter battens, it is
recommended that the tile fasteners be of sufficient length to penetrate the
underside of the horizontal counter battens by ¼ inch minimum. It is recommended
that the batten-to-batten connections be engineered.

For roofs within 3,000 feet of the ocean, straps, fasteners, and clips should be
fabricated from stainless steel to ensure durability from the corrosive effects
of salt spray.

3. Hips and Ridges
The Concrete and Clay Roof Tile Installation Manual gives guidance on two
attachment methods for hip and ridge tiles: mortar-set or attachment to a ridge
board. On the basis of post-disaster field investigations, use of a ridge board
is recommended. For attachment of the board, refer to Table 21 in the Addendum
to the Concrete and Clay Roof Tile Installation Manual.

Fasten the tiles to the ridge board with screws (1-inch minimum penetration into
the ridge board) and use both adhesive and clips at the overlaps.

For roofs within 3,000 feet of the ocean, straps, fasteners, and clips should be
fabricated from stainless steel to ensure durability from the corrosive effects
of salt spray.

4. Critical and Essential Buildings (Category III or IV)
Critical and essential buildings are buildings that are expected to remain
operational during a severe wind event such as a hurricane. It is possible that
people may be arriving or departing from the critical or essential facility
during a hurricane. If a missile strikes a tile roof when people are outside the
building, those people may be struck by tile debris dislodged by the missile
strike. Tile debris may also damage the facility. It is for these reasons that
tiles are not recommended on critical or essential buildings in hurricane-prone
regions (see ASCE 7 for the definition of hurricane-prone regions).

If it is decided to use tile on a critical or essential facility and the tiles
are mechanically attached, it is recommended that clips be installed at all
tiles in the corner, ridge, perimeter, and hip zones (see ASCE 7 for the width
of these zones). (See Figure 1.)

Figure 1: for critical and essential facilities, clip all tiles in the corner,
ridge, perimeter, and hip zones.

5. Quality Control
It is recommended that the applicator designate an individual to perform quality
control (QC) inspections. That person should be on the roof during the tile
installation process (the QC person could be a working member of the crew). The
QC person should understand the attachment requirements for the system being
installed (e.g., the type and number of fasteners per tile for mechanically
attached systems and the size and location of the adhesive for foam-adhesive
systems) and have authority to correct noncompliant work. The QC person should
ensure that the correct type, size, and quantity of fasteners are being
installed.

For foam-adhesive systems, the QC person should ensure that the foam is being
applied by properly trained applicators and that the work is in accordance with
the foam manufacturer’s application instructions. At least one tile per square
(100 square feet) should be pulled up to confirm the foam provides the minimum
required contact area and is correctly located.

If tile is installed on a critical or essential building in a hurricane-prone
region, it is recommended that the owner retain a qualified architect, engineer,
or roof consultant to provide full-time field observations during application.

Footnote: * You can order the Concrete and Clay Roof Tile Installation Manual
online at the website of the Florida Roofing, Sheet Metal and Air Conditioning
Contractor’s Association, Inc., (
www.floridaroof.com) or by calling (407) 671-
3772. Holders of the Third Edition of the Manual who do not have a copy of the
Addendum can download it from the website.