Historic Preservation - Technical Procedures
- Replacing Loose, Broken Or Missing Clay Roof Tiles
- Procedure code:
- Hspg Prepared For Nps - Sero
- Thermal And Moisture Protection
- Clay Tiles
- Last Modified:
- Replacing Loose, Broken Or Missing Clay Roof Tiles
- Last Modified:
REPLACING LOOSE, BROKEN OR MISSING CLAY ROOF TILES
A. This procedure includes guidance on replacing clay roof
tiles that are loose, broken, or missing.
THIS WORK SHOULD BE DONE BY AN EXPERIENCED ROOFING
B. See 01100-07-S for general project guidelines to be
reviewed along with this procedure. These guidelines
cover the following sections:
1. Safety Precautions
2. Historic Structures Precautions
4. Quality Assurance
5. Delivery, Storage and Handling
6. Project/Site Conditions
7. Sequencing and Scheduling
8. General Protection (Surface and Surrounding)
These guidelines should be reviewed prior to performing
this procedure and should be followed, when applicable,
along with recommendations from the Regional Historic
Preservation Officer (RHPO).
C. For guidance on cleaning blackened clay roofing tiles,
1.02 SYSTEM DESCRIPTION
A. A good roofing tile should be well and evenly burnt
throughout, compact, hard yet tough, free from pinholes,
lumps, or specks of unslaked lime, cracks or laminations,
glazed or vitrified patches on the bed or underside, must
not be warped or otherwise distorted, must not have
broken edges or corners, and must not have high absorbent
qualities. It should also comply with ASTM standards for
strength in resistance to compressive and tensile loads.
B. A dense well-burned tile will show a clean fracture when
struck sharply with the edge of a trowel; a soft tile
will crumble, and an overburnt tile will splinter or
C. A clay tile roof in good condition is free of any loose,
broken, or missing field tiles. All starter tiles,
circular cover starter tiles, eave closure tiles, top
fixture pieces, ridge covers and other "special tiles"
are also in place. The roof surface is clear of all
debris so that rainwater flow is not impeded.
1.03 DELIVERY, STORAGE, AND HANDLING
A. Storage and Protection:
1. Store tile roofing materials in a dry location.
When stored outside, place on platforms off the
ground covered with waterproof coverings which will
not produce any condensation.
2. Field tile is generally shipped in pallets, and
fittings in boxes. Upon receipt of the shipment,
pallets and boxes should be inspected for
transportation damage. Examine the tiles for color
by taking 10 field tiles at random from each of the
pallets. Spread them out and observe the shade
variation. The range of shades is a prime reason
why a tile roof is so handsome. Replace the
material in its original containers for storage.
Pack any existing extra stock in similar manner.
3. Power equipment is needed to deliver the tiles to
the roof level. Outside storage is acceptable.
Manufacturers supply instructions for stacking
tiles on gable and hip roofs so that loads are
properly placed and the tiles located for minimum
handling by the tile applicator. Proper job
organization is important to save unnecessary
movement of heavy units.
1.04 PROJECT/SITE CONDITIONS
A. Environmental Requirements:
1. Do not replace or repair tile roofs in wet weather.
2. Do not remove roofing from structures when rain is
forecasted or in progress.
3. If roofing is to be removed on a clear day, remove
no more than can be replaced or repaired in one
A. Like slate, tile requires little ongoing maintenance:
1. Clay tile requires no painting, no preservative
coatings, waterproofing or fireproofing, and almost
2. Its very low porosity makes it extremely weather
3. Clay tiles can last many years. Thin, flat
shingles can last at least 75 years. Barrel tiles
have been known to last 350 years.
B. Clay tile roofs are especially susceptible to mechanical
damage from walking on tiles or from fallen tree limbs or
other objects. Adjacent trees and landscaping should be
kept trimmed to avoid breakage, and heavy pads and ridge
ladders should be used to equalize a person's weight
whenever any work is to be done on the roof.
C. In addition to scheduled inspections, inspect after each
exposure to unusually severe weather conditions such as
strong winds, hail, or long continuous rains.
A. Boston Valley Terra Cotta
Manufactures custom-made roof tiles and architectural
terra cotta for like replacement. Specialize in
restoration projects, will match color, texture, and
detail. Free literature.
B. Gladding, McBean & Co.
Clay roofing tiles sold through distributors. Free
C. Ludowici Roof Tile Co.
Clay roofing tiles in traditional patterns and imitation
wood are sold direct and through distributors. Free
product sheets on each style.
D. Midland Engineering Co.
A major distributor for roofing products including German
clay tiles and Vermont slate, sold through roofers and
direct. Free brochures on all products - specify your
E. Vande Hey Raleigh
Manufactures a broad line of extruded concrete roofing
tiles, including a simulated slate and a Mission tile.
Also has a large stock of recycled slate, concrete, and
clay tiles. Free literature.
A. Salvaged or replacement clay tile to match existing (see
companies listed above in Section 2.01).
B. Nails: Use 1-3/4" copper nails, or length and holding
power as recommended by the shingle manufacturer. The
nails should be long enough to penetrate through the
roofing material and at least 3/4 inches into the deck
NOTE: STAINLESS STEEL TABS WITH STAINLESS STEEL NAILS
MAY BE USED IF NO DANGER OF GALVANIC ACTION EXISTS.
DIRECT CONTACT WITH, OR RAINWATER RUN-OFF FROM COPPER,
ALUMINUM AND ALUMINUM ALLOYS, STEEL AND ZINC WILL CAUSE
STAINLESS STEEL TO CORRODE.
C. Sealant: Clear Silicone Rubber Sealant
or clear silicone sealant of highest quality.
D. Elastic cement: Use only non-staining, non-corrosive
cement as recommended by the manufacturer.
A. Rule or Tape
C. Chipping Hammer
E. Fox-tail Broom
F. Caulking Gun
G. Slate Ripper
H. Drill and Glass Drill Bits
A. Whenever possible, make inspection from ground or from
above if possible. Inspect for:
1. Biological growth: Inspect for dirt build-up,
biological attack, mold, fungus. Also inspect for
buildup of debris and vegetation such as moss or
lichen. Heavy coatings of any type form dams and
stop natural drainage, resulting in various types
of deteriorations. This is more apt to occur on
2. Individual tiles: Inspect tile ridge details and
starter courses for missing, loose, broken, or out
of place tiles.
3. Wear: Excessive weathering, spalling or staining
indicating weathering and age. Tile movement may
be detected by unusually clean areas (lack of
stains). Movement is often a sign of failed
4. Leaks: Inspect the underside of the roof deck from
the attic to detect leaks. Flashings are the most
vulnerable points. Therefore, inspect the
underside carefully at all flashing points and
along downhill side of any roof penetrations for
evidence of leakage such as water stains.
1. Establish rules for any foot traffic that may be
required during repair operations.
a. Ideally, clay tile should not be walked on.
b. Lay down heavy padding and then hang a self-
supporting ladder over the ridge of the roof.
c. Ladders to the roof should be secured at the
top to prevent any sliding or fall-out from
the building. The ladders should be set on an
incline whereby the bottom of the ladder is
approximately 25% of the height from the base
of the building.
2. Safety on the roof:
a. Wear rubber-soled shoes that have non-slip
tread (preferably sneakers with a high top for
good ankle support). Avoid wearing loose
b. Wear safety-belt or harness and secure to the
chimney (if it's in good shape) or to a window
on the opposite side of the building. Leave
only enough slack so you can work comfortably
in one area, and adjust the slack as you work
on other sections of the roof.
c. Be sure the roof is clear of debris and water.
Avoid stepping on damaged or crumbling roofing
3. Steep roofs: On slopes where the roof is steeper
than 4 inches rise per foot, special consideration
must be given to footing and handling of materials.
a. Chicken ladders or cleats shall be used on the
roof as required for adequate footing.
b. Safety lines, of an approved type should be
properly worn and secured with ropes of sufficient strength.
Rubber-soled shoes with grip-type bottom
should be worn.
c. Carrying and transporting of materials should
be limited to a safe amount so that balance
and footing are not impaired.
d. Do not work on roof when wet or snow-covered.
B. Surface Preparation:
1. Carefully examine, measure, and record existing
tile patterns at edges, hips, ridges, and other
special conditions. Measure the exposed dimensions
and amount of lap of each type piece prior to the
removal, as well as length, width, and thickness
2. For safety of the personnel, keep the deck clear of
waste material as the work proceeds. Sweep the
deck clean after all loose or broken pieces have
3.03 ERECTION, INSTALLATION, APPLICATION
A. Salvaging a Broken or Loose Tile: If the shingle tile is
broken at the nail hole, salvage the tile by carefully
drilling a new hole with a carbide-tip drill and nailing
the tile in place with a hammer so that the tile "hangs"
on the nail.
B. Replacing Shingle Tiles:
1. Remove loose tile(s).
a. If tile is to be salvaged and reused,
carefully remove nails using either a slate
ripper, or insert a hack saw blade under the
cover tile and saw through the nail.
b. If the tile is already broken, light blows
with a hammer to further break it into pieces
will facilitate removal.
2. Select a replacement tile of proper size to match
existing, allowing a typical gap on each side.
NOTE: NOTHING LOOKS WORSE THAN UNMATCHED TILES
NEXT TO EACH OTHER IN THE SAME COURSE. TO BLEND
THE NEW TILES IN WITH THE OLD, DON'T MIX THEM ON
THE SAME ROOF PLANE. PUT THE NEW ONES ON DORMER
ROOFS, ON A CLIPPED GABLE, OR IN SHADOWS.
3. Slide the replacement tile into position.
4. After aligning it carefully, drill a hole right
below the slot of the two covering tiles.
NOTE: MAKE SURE YOU DRILL THE HOLE ABOVE THE
DOUBLE COVERAGE; YOU WANT A HOLE ONLY IN THE NEW
TILE, NOT THE ONE BELOW IT.
5. Hold the new tile in place using a heavy gauge
copper wire nail with a large flat head.
NOTE: ITS LENGTH SHOULD BE TWICE THE THICKNESS OF
THE TILES PLUS ONE INCH.
6. Drive the nail between the covering tiles.
7. Cover the nailhead (also known as "making a baby"):
a. Bend a strip of copper about 2" wide and 6"
long into a slightly concave shape to make a
cover for the exposed nailhead.
b. After tile is secure, slide copper strip under
the tile positioned above the tile just
replaced until the bottom of strip is 2" below
a. Secure with a 1" wide copper tab (20 oz).
Nail the copper tab into the deck between the
butt joint of the two tiles below.
b. Seal the nail hole with a nonstaining,
noncorrosive cement as recommended by the
manufacturer and suitable for use with copper.
c. Lay in the new tile and bend tab up and over
the end of the tile to hold it in place. The
tab should be doubled at the bent end to
provide extra stiffness to the tab.
B. Repair of Barrel Tile:
1. Remove loose or broken tile and select replacement
(see Section 3.03 A.1. and 2. above).
2. Nail copper tabs with copper nails to supporting
batten or sheathing. For nails through sheathing,
seal with a nonstaining, noncorrosive cement as
described in Section 3.03 B.7. above.
3. Bend tab as above to hold tile in place (see
Section 3.03 B.7.c. above).
END OF SECTION