Flashing details for clay tile roofs:
This article describes the special connection methods used seal or close the ridge, hip, and rake sections of clay tile roofs.
Because of the longevity of a tile roof, high-quality flashing materials should be used. The International Residential Code calls for a minimum 26-gauge metal. Galvanized steel should have a minimum of 0.90 ounces of zinc per square foot (G90 sheet metal).
More expensive options include prepainted galvanized steel or 16-ounce sheet copper.
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This article series discusses best practices in the selection and installation of residential roofing. This article includes excerpts or adaptations from Best Practices Guide to Residential Construction (Steve Bliss, J Wiley & Sons) , by Steven Bliss, courtesy of Wiley & Sons.
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At walls, dormers, chimneys, and other vertical surfaces, extend the flashing up at least 6 inches and counterflash.
Extend the clay tile flashing under the tile a minimum of 6 inches or as specified by the tile manufacturer.
With flat style clay shingles, use step flashing with a minimum 6-inch vertical leg and 5-inch horizontal leg with a hemmed edge.
Profile style clay tiles along a wall should receive channel flashing turned up at least one inch on the lower flange (Figure 2-32 shown at left).
Pipe flashings protruding through a clay tile roof generally get both a primary flashing when the underlayment is installed and a secondary soft-metal underlayment that conforms to the tile.
For profile style clay roofing tiles, this can be 2 1/2 -pound lead or dead-soft aluminum with an 18-inch-wide skirt (Figure 2-33 shown here).
According to the International Residential Code (IRC), valley flashing in tile roofs should extend at least 11 inches each way from the valley centerline, and the flashing should have a formed splash diverter at the center at least one inch high.
The code requires a minimum underlayment at the valley of 36-inch-wide Type I No. 30 felt in addition to the underlayment for the general roof areas.
In cold climates (average January temperature of 25°F or less), a self-adhering bituminous underlayment is recommended. Battens, if used, should stop short of the valley metal.
Tiles along the valley edge may be laid first and cut in place along a chalked line. Cut pieces are attached by roofing cement or a code-approved adhesive, or they may use wire ties, tile clips, or batten extenders.
Open clay tile roof valleys on clay or other tile roofs permit free drainage and are recommended in areas where leaves, pine needles, and other debris are likely to fall on the roof.
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The open valley on the New York clay tile roof shown above has been patched more than once.
They are also recommended in areas subject to snow and ice buildup.
Above our photo of an open valley on a clay tile roof demonstrates how a snow guard can block drainage of a roof valley, leading to debris clogging.
[Click to enlarge any image]
The valley flashing for a tile roof should have hemmed edges and be installed with cleats that allow individual sections to expand and contract (Figure 2-34).
In this type of valley, the flashing carries the runoff and the tile in the valley is only decorative. These are not recommended where debris from trees may fall on the roof or where the two roof planes joining at the valley have different pitches or length, causing uneven flows.
Our photograph of a closed tile roof valley (above) was taken at a home in Surprise, Arizona, in an area where there were few trees or any other leafy plants.
To prevent breakage, walk on tiles with extreme caution.
Profile tile and lightweight tile are the most vulnerable, and concrete tiles are more fragile when they are freshly manufactured or “green.” If possible, place antennas and other roof-mounted equipment where it is easy to access without crossing many tiles.
When it is necessary to walk on tiles, step only on the head-lap (lower 3 inches) of each tile.
With Mission- or S-tiles, it is best to step across two tiles at once to distribute the weight. When significant rooftop work is required, place plywood over the tile to distribute the load.
Watch out: our own experience is that it is absolutely impossible to walk on many clay tile roofs without damaging them, particularly soft clay such as the roof type used in Latin America (our photo at left).
For these roofs contractors have to remove sufficient clay tiles to provide a walking area. The removed tiles are replaced as the worker is leaving the work area of the roof.
On some other fragile but not totally fragile roofs such as slate roofs, cement tile, cement-asbestos, fiber cement, and hard-fired ceramic clay tile roofs, contractors suspend a ladder over the roof surface, hanging it from the ridge, and cushioning it off of the roof surface using foam or insulation padding, or contractors work from scaffolding. - Ed.
See ROOF INSPECTION SAFETY & LIMITS where we describe roof safety and roof damage issues when inspecting, repairing, or otherwise walking on clay tiles as well as other roof materials such as asphalt, slate, and wood roofs.
If a roofing tile is cracked, gently lift the overlapping tile and wiggle loose the damaged tile.
Remove the roof tile nail, screw, or clip with a slate ripper or hacksaw blade.
Seal any nail holes with roofing cement and slip a new tile into place, securing the butt end with an L-hook or bent copper wire (as shown in Figure 2-35).
- - Adapted with permission from Best Practices Guide to Residential Construction (Steve Bliss, J Wiley & Sons) .
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Below you will find questions and answers previously posted on this page at its page bottom reader comment box.
On 2020-02-26 - by (mod) -
Anon:
Clay and concrete tile roofing guides (documents provided in this article series) discuss open and closed valley designs and underlayments extensively but I don't generally see attention to the cosmetic detail of how the abutting valley tiles are trimmed to fit neatly.
Illustration adapted from Ludowici cited above. [Click to enlarge any image]
Key is a reliance on the valley flashing to avoid roof leaks, leaving the tile abutments at the valley as a cosmetic details
except
as I suggested earlier, that if the valley underlayment is a membrane rather than metal, exposure to sunlight may reduce its life.
Boral Roofing provides that company's guide to valley installation at
VALLEY FLASHING INSTALLATION, RIBBED [PDF] (2016) Boral Roofing, retrieved 2020/02/26, original source: www.boralroof.com/wp-content/uploads/boral-resource/Ribbed-Valley-Metal-Installation.pdf
Excerpt: A closed or open valley is optional, but should be dictated by site
conditions. A closed valley is created when the roof tiles are cut close to
the center of the valley. An open valley has a 4-8-inch wide open trough
down the center of the Ribbed Valley Metal, created when the roof tiles are
cut 2-4-inches from the center of the valley on each side. In areas subject
to snow or ice damming, open valleys should be cut in a taper to widen
toward the down-slope with a minimum 1/8-inch per foot.
Ludowici roofing, in the company's barrel tile installation manual cited above, describes open tile roof valleys and cites "mission field cut valley tiles" suggesting that the roofer needs a tile saw to make appropriate cuts to bring the diagonal end of the valley tiles sufficiently and uniformly close to the valley center.
The company also notes that the field-cut valley tiles can be pointed with mortar. - Illustration below excerpted and adapted from Ludowici cited above.
On 2020-02-25 18 by Anonymous - closed valley for Boral roof tiles?
is there any step by step installation guidelines of how to install a closed valley (boral tiles)?
Michael
If we can see valley underlayment then it's not a successfully-built "closed valley".
**IF** the valley liner is sufficiently durable, waterproof, wide, and properly installed such that it's not going to be damaged by sun and weather exposure, what remains might be a cosmetic issues.
On 2020-02-22 by Michael
in a closed valley installation should the tiles be aligned at center of the valley? High point of one tile meeting with the high point of the another tile or not?
We have openings at the middle line ( valley) because tiles are not meeting high end with high and low end with low end.
On 2020-01-08 by danjoefriedman (mod) - contractor required to repair flashing not installed according to manufacturer's specifications
Lothar that detail is not provided in any building code that I've seen.
I don't think we can rely on "code compliance" for ever good construction practice detail. The code writers know this, which is why you'll often also see ".... must be installed according to the manufacturer's specifications"
See flashing details for clay tile roofs
at FLASHING, CLAY TILE ROOFS
Arizona provides these
On 2020-01-07 by Lothar Martin
how far have valley metals to extend past the roofline in arizona?
I would like to have the protruding valley trimmed back to roof line, but the roofer says that would be against code.
What is the right answer?
This clay tile roof flashing question was posted originally
at ROOF FLASHING, ASPHALT SHINGLE VALLEYS
On 2019-10-04 - by (mod) -
Siu
Please post questions just once on one page - we have many readers to whom we want to respond
https://inspectapedia.com/BestPractices/Best_Roofing_Underlayment.php
On 2019-09-29 by Siu
Mission tile roof with steep slope
Contractor is to re-roof and reset the entire
Question:
Is it ok / effective that the contractor only to remove existing underlayment as needed but will install APOC base (CX-L Crossover Hybrid Roof Underlayment) using plastic cap nails to entire roof field
Thank you
On 2018-07-23 - by (mod) -
Roof.
You always want to dry in first on a building before putting on the interior wall finishes - almost any material otherwise you risk water damage to the wall coming through the interior when it rains.
So you need the roof to have been installed and it's best also to have a working gutter system sufficiently that you can keep rain splash from falling off the roof and onto your siding while the work is being done.
On 2018-07-22 by pat
What should be done first? I have a small addition. Installing the roof over the new addition OR doing the outside stucco work?
On 2017-08-01 - by (mod) -
Bruce
Sorry but I'm not sure what you mean by horizontal roof projections.
However you might be able to get the exit venting you need by construction of appropriately located dormers on the roof that are sized and fitted to serve as exit vents.
On 2017-07-31 by Bruce youngman
I need to put in large roof vents to accommodate a full house fan. I have a clay tile roof is there any flashing available to work with horizontal roof protrusions?
On 2017-02-15 - by (mod) - sealant around plumbing vents?
Mike
I would never rely on a sealant to seal vent pipes protruding through a tile roof, as temperature and other weather changes ultimately lead to nasty leaks at the penetration.
I would find, buy, or fabricate appropriate vent stack flashing (that combines metal flashing shaped to fit the tiles and a rubber boot that seals around the vent pipe) that intercepts water and directs it out onto the tiles below the vent.
That said, silicone sealant is durable and bonds well to most clean dry materials.On 2017-02-14 2 by Mike
What sealant do I use around vent pipes on tile roof
...
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