Technical Procedures Disclaimer
Prior to inclusion in GSA’s library of procedures, documents are reviewed by one or more qualified preservation specialists for general consistency with the Secretary of Interior Standards for rehabilitating historic buildings as understood at the time the procedure is added to the library. All specifications require project-specific editing and professional judgement regarding the applicability of a procedure to a particular building, project or location. References to products and suppliers are to serve as a general guideline and do not constitute a federal endorsement or determination that a product or method is the best or most current alternative, remains available, or is compliant with current environmental regulations and safety standards. The library of procedures is intended to serve as a resource, not a substitute, for specification development by a qualified preservation professional.
We’ve reviewed these procedures for general consistency with federal standards for rehabilitating historic buildings and provide them only as a reference. Specifications should only be applied under the guidance of a qualified preservation professional who can assess the applicability of a procedure to a particular building, project or location. References to products and suppliers serve as general guidelines and do not constitute a federal endorsement nor a determination that a product or method is the best alternative or compliant with current environmental regulations and safety standards.
- This procedure includes guidance on replacing clay roof tiles that are loose, broken, or missing. THIS WORK SHOULD BE DONE BY AN EXPERIENCED ROOFING CONTRACTOR
- See 01100-07-S for general project guidelines to be reviewed along with this procedure. These guidelines cover the following sections:
- Safety Precautions
- Historic Structures Precautions
- Quality Assurance
- Delivery, Storage and Handling
- Project/Site Conditions
- Sequencing and Scheduling
- 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).
- For guidance on cleaning blackened clay roofing tiles, see 07321-02-R.
1.02 SYSTEM DESCRIPTION
- 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.
- 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 crack.
- 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
- Storage and Protection:
- 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.
- 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.
- 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
- Environmental Requirements:
- Do not replace or repair tile roofs in wet weather.
- Do not remove roofing from structures when rain is forecasted or in progress.
- If roofing is to be removed on a clear day, remove no more than can be replaced or repaired in one day.
- Like slate, tile requires little ongoing maintenance:
- Clay tile requires no painting, no preservative coatings, waterproofing or fireproofing, and almost no cleaning.
- Its very low porosity makes it extremely weather resistant.
- Clay tiles can last many years. Thin, flat shingles can last at least 75 years. Barrel tiles have been known to last 350 years.
- 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.
- In addition to scheduled inspections, inspect after each exposure to unusually severe weather conditions such as strong winds, hail, or long continuous rains.
- Boston Valley Terra Cotta
6860 South Abbott Rd
Orchard Park, NY 14127
Manufactures custom-made roof tiles and architectural terra cotta for like replacement. Specialize in restoration projects, will match color, texture, and detail. Free literature.
- Gladding, McBean & Co.
601 7th Street,
Lincoln, CA 95648
Clay roofing tiles sold through distributors. Free roofing brochure.
- Ludowici Roof Tile Co
4757 Tile Plant Rd.
PO Box 69
New Lexington, Ohio 43764
Clay roofing tiles in traditional patterns and imitation wood are sold direct and through distributors. Free product sheets on each style.
- Midland Engineering
52369 S.R. 933 North
South Bend, IN 46637
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 interest.
- Vande Hey Raleigh Mfg., Inc.
1665 Bohm Drive
Little Chute, WI 54140-2529
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.
- Salvaged or replacement clay tile to match existing (see companies listed above in Section 2.01).
- 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 lumber section.
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.
- Sealant: Clear Silicone Rubber Sealant or clear silicone sealant of highest quality.
- Elastic cement: Use only non-staining, non-corrosive cement as recommended by the manufacturer.
- Rule or Tape
- Chipping Hammer
- Fox-tail Broom
- Caulking Gun
- Slate Ripper
- Drill and Glass Drill Bits
- Whenever possible, make inspection from ground or from above if possible. Inspect for:
- 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 north slopes.
- Individual tiles: Inspect tile ridge details and starter courses for missing, loose, broken, or out of place tiles.
- 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 fastenings.
- 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.
- Establish rules for any foot traffic that may be required during repair operations.
- Ideally, clay tile should not be walked on.
- Lay down heavy padding and then hang a self- supporting ladder over the ridge of the roof.
- 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.
- Safety on the roof:
- Wear rubber-soled shoes that have non-slip tread (preferably sneakers with a high top for good ankle support). Avoid wearing loose clothing.
- 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 in one area, and adjust the slack as you work on other sections of the roof.
- Be sure the roof is clear of debris and water. Avoid stepping on damaged or crumbling roofing materials.
- 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.
- Chicken ladders or cleats shall be used on the roof as required for adequate footing.
- 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.
- Carrying and transporting of materials should be limited to a safe amount so that balance and footing are not impaired.
- Do not work on roof when wet or snow-covered.
- Establish rules for any foot traffic that may be required during repair operations.
- Surface Preparation:
- 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 after removal.
- 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 been removed.
3.03 ERECTION, INSTALLATION, APPLICATION
- 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.
- Replacing Shingle Tiles:
- Remove loose tile(s).
- 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.
- If the tile is already broken, light blows with a hammer to further break it into pieces will facilitate removal.
- 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.
- Slide the replacement tile into position.
- 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.
- 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.
- Drive the nail between the covering tiles.
- Cover the nailhead (also known as "making a baby"):
- Bend a strip of copper about 2" wide and 6" long into a slightly concave shape to make a cover for the exposed nailhead.
- After tile is secure, slide copper strip under the tile positioned above the tile just replaced until the bottom of strip is 2" below nailhead.
- 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.
- Seal the nail hole with a nonstaining, noncorrosive cement as recommended by the manufacturer and suitable for use with copper.
- 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.
- Remove loose tile(s).
- Repair of Barrel Tile:
- Remove loose or broken tile and select replacement (see Section 3.03 A.1. and 2. above).
- 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.
- Bend tab as above to hold tile in place (see Section 3.03 B.7.c. above).