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Hip Roof Chimney Leaks Image

Hip roofs are great for resisting strong winds, shedding water, and providing shade on all fours. However, as one report explains, hip roofs and chimneys are at odds with each other.

One troubled reader asks certified home inspector Dwight Barnett for help. It seems as if his chimney leaks no matter what he does, particularly putting as much sealant and flashing as possible. As it turns out, the “all-fours” design hip roofs sport gives no respite to chimneys and other penetrations.

No matter where you place the chimney on a home with a hip roof, the roof will drain toward the chimney and no amount of flashing material will hold back the torrents of rain and snowmelt.

Hip roofs aren’t like gable roofs where precipitation only has two ways to go down. This is why many skilled roofers in Maryland like DryTech Roofing install essential flashing on places where the roofing material and penetration meet. Among these is a cricket, sometimes called a chimney cricket.

Required by Code

The need for crickets appears on the 2012 International Building Code (IBC), the latest version, under Section 1503. According to the code, any chimney more than 30 inches wide must have a cricket installed perpendicular to the slope. This also applies to other penetrations such as vents but skylights are an exception (as they have a different standard).

On a related note, the cricket’s height, which depends on the slope of the roof in question, must also comply with codes. A chimney penetrating a roof with a slope of 6:12 must be protected by a cricket with the height of 25 percent of the chimney’s width. As the minimum width required for chimneys is at 30 inches, the cricket— in this case— must be 7.5 inches tall.

The codes, however, don’t say anything about the ideal pitch or slope angle of the cricket. Many roofers suggest a cricket with the same pitch as the roof being installed on.

Materials and Repair

It doesn’t take much to construct a cricket; some roofers have done it using a combination of wooden frames, step flashing, and asphalt shingles to match. In some cases, metal crickets are used primarily to match metal roofing. The important thing is that the cricket holds firm against a heavy torrent.

Nevertheless, a cricket doesn’t eliminate the need for Maryland roof repair. Penetrations, on a roofing perspective, are always the most critical parts of the roof as far as leaks are concerned. The codes specify a one-inch air space between the chimney wall and the edge of the cricket for ventilation.

 

(Article excerpt from “A hip roof leads to chimney leaks,” Scripps Howard News Service [c/o The Seattle Times], May 7, 2012)