By Randy Frassetto
Published Tuesday, September 25, 2012
| From the November 2012 Issue of FireRescue
In the first part of this two-part series (For part 1, see the September issue; www.firefighternation.com/article/truck-co-operations/tile-roof-tactics-considerations-part-1), I covered the difference between two common roof materials, concrete and clay tile, and described ventilation techniques for opening a roof covered with concrete tiles. In this article, I’ll focus on the building construction considerations and tactical approach for ladder crews dealing with a structure covered in clay tiles.
Clay Tile Basics
Clay tiles have been in use for many years and are still installed in both residential and commercial applications. Clay tiles differ from concrete in regards to weight, attachment methods and the way the roof below them may be constructed. It’s important that the company officer understand the hazards associated with clay tiles before committing their crew to perform vertical ventilation.
Clay tiles can weigh anywhere from 12 to 16 lbs. per square foot, and that doesn’t include the mortar that’s often used to attach or repair them. They come in both one-piece “S-tiles” and two-piece “pans and tops tiles” that can range from about 6 to 14 inches in width. Clay tiles are made of sand cast or fire clay and therefore break easily. Although newer constructed roofs are designed to carry the weight of clay tiles, some clay tiles may be sitting atop a roof that’s not designed for this added weight. A roof that’s old may no longer have the structural integrity to support the dead load that it originally had on it.
The method with which clay tiles are installed will play into the tactical operations. Guide wires are run from the ridge to the ledge of the structure where each column of tiles will be placed. Each tile is then placed on top of the guide wire and attached individually using a guide wire (or wires) placed through the top of each tile. Another method to attach tiles to a roof is to nail each individual tile into a wood strip and the sheathing/decking of the roof. Often, roof tiles will have mortar that’s used to repair broken tiles. This method for fixing tiles has become an aesthetic trend for a “Tuscan” look, so it’s common to see an entire tile roof with mortar protruding from each individual tile.
When it comes to roof construction, clay tile is placed on everything from very old to brand new buildings. Although conventional-style roofs have been known to be more stout than lightweight trusses under fire conditions, it’s important to note that older constructed roofs may be weaker due to age. Termites, weather and age alone can cause these roofs to fail quickly, even when they’re not exposed to fire. As such, firefighters should be familiar with both conventional and lightweight construction methods, as they play a vital role in firefighting and ventilation tactics.
As in all fires, the best time to devise a plan is prior to the fire. Driving around your first-due and walking around structures can give you a ton of information that will be beneficial when responding to a fire in the same area. Get an overall impression of the structure to determine the type and condition of the roof that the tiles are covering. Looking under the eaves often provides a great cross-section of what the rest of the roof may look like.
Situational awareness and determining what type of fire (structure, contents or both) both play a vital role in determining ventilation tactics. Positive pressure attack (PPA) is an outstanding choice for ventilation, but it has to be in the department’s tactical playbook and should be performed prior to crews operating interior. If a contents fire is present with no attic involvement, a rooftop ventilation operation may be feasible—but only after determining the tenability of the roof. If fire is in the attic space, the company officer should identify if there is enough unburned attic space to operate on and if cutting a hole will support the interior crews’ fire suppression tactics (i.e., steam conversion). Oftentimes a hole may only need to be cut to slow the progression of the fire if the crews interior can’t get ahead of the fire spread.
Once the CO has made the decision that a rooftop operation will be conducted, the CO should check and re-check what firefighters will be operating on top of. Before a ladder is even climbed, look underneath the overhang. Often this will be a direct reflection of what the tile is sitting on top of. Make note of rafter or truss dimension, spacing and condition, as well as what type of sheathing is on top of the roof. It’s extremely important to remember that a conventional-style rooftop may be weakened due to age, termites and/or exposure to the elements.
Assuming that the area underneath the roof appears to be tenable, once a ladder is thrown, crews should be able to identify the method used to attach the clay tiles and confirm the roof sheathing construction. Tiles can be easily broken using an axe, a trash hook or any similar tool brought to the roof. While remaining on the load-bearing wall, break a tile and see if it’s nailed, concreted in place or attached to a cable. Once the attachment method is identified, remove the underlayment to expose the roof sheathing/decking. If the roof construction is deemed to be good enough on which to operate, use a back cut and/or sounding to identify a structural member and determine rafter spacing. It’s important that firefighters remain on structural members (rafters) for the duration of the roof operation, cutting over smoke, not fire.
While advancing to the ridgeline on a structural member, continuously sound the roof for tenability while creating smoke holes or monitoring attic vents to identify attic space conditions. Once crews reach the area where the vent hole will be cut, remove enough tiles parallel to the ridgeline to allow for the head cut.
Nailed/Concreted Tile Removal
If tiles are concreted and/or nailed individually, the first row may need to be broken to allow firefighters enough space to get their hands on the remaining tiles. Once the first row is removed, grab the top of the tile as close to the nail as possible and pull upward. Working down toward the load-bearing wall, remove enough tiles to complete an adequate size ventilation hole.
Wire-Attached Tile Removal
To remove tiles that are individually attached to a tie wire, break tiles where the head cut will be completed. Once the tiles are broken, cut the tie wire that is running from the ridge to the ledge for each column. The column of tiles can then be pulled downward until there’s enough of an opening to cut a ventilation hole. Columns may be pushed off to the side to keep the area where firefighters are operating clear.
Clay tiles often mask the condition of the roof on which they sit. Even if tiles appear to be a newer install, ladder companies should be skeptical about what lies beneath them. A tactical consideration should be the time it takes to complete a clay tile roof operation due to tile removal, and company officers should sacrifice space for time to conduct this operation.
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