Ten Most Common Roofing Mistakes - Part 1

Roofing shingles are not waterproof. If the slope of the roof is too low, water can run under the edges of the shingles into the structure.

We see this all of the time on screen porches and covered decks. Most single sloped roof pitches are determined by the height of the windows on the second floor. This limits the pitch of the roof. According to most manufacturers, the pitch of the roof should be a minimum of 2/12 or the rise should be 2 inches for every 12 inch horizontal measurement. Anything lower that 2/12 is subject to leaking. If you have a low slope roof, the solution is a membrane roof with the edges sealed. This material normally comes in 36 inch wide rolls that should be installed by a roofing professional.

Drip edge goes around the perimeter of the roof to prevent water from running under the edges of the

shingles into the structure. First, the drip edge gets nailed in place along the lower edge of the roof. Next, the roofing felt goes on top of the drip edge to prevent water from entering at the eave. Felt comes in 15 lb and 30 lb rolls. Once the deck is completely covered, install more drip edge along the rakes on top of the felt. This holds the felt in place and prevents the ends from curling.

A starter course of shingles is next. Make these by cutting the tabs off full shingles and using just the top portion with the adhesive strip at the bottom. Then nail the starter course to the roof so the edges and ends are flush with the drip edge. The starter course fills in the gap between the tabs and seals the first course at the gutter line.






Every penetration through the roofing shingles is a potential roof leak. Plumbing vents, furnace vents,

chimneys, dormers, skylights, valleys and vertical walls are all sources of potential leaks. To prevent leaks, a leak barrier is recommended around these items to insure the shingles are totally sealed to prevent the possibility of a leak. A leak barrier is a self-adhering, waterproof, rubberized membrane that is installed in the most vulnerable areas on the roof prior to installing the shingles.  Once installed, a leak barrier will seal to the roof deck surface and around any penetrations to create a watertight surface. Leak barriers are not required by the building codes, but are recommended by professional roofers.  

Most roofers use pneumatic nail guns to nail down shingles. When the pressure is set too high, the nails get driven into the shingles too far.  When the nails are overdriven, the heads of the nails punch right through the mat of the shingle and  the nail heads lose their ability to hold the shingles in place. This voids the shingle manufacturers’ warranty and greatly increases the potential for shingles to come loose and blow off, possibly in sheets.


Another problem is exposed nails in the roof flashing. Every exposed nail is a potential for a roof leak. There should be no exposed nails in any roof except at the end ridge shingle. Just sealing the nails is not an option since the sealant will eventually dry out and pop off.
The last item is toe board nail holes. Some roofers nail 2x4s over the shingles to use as walk boards. When they finish  the roof, they remove the boards which leave holes in the roof shingles. Any hole in the shingle is a roof leak that will take up to ten years to deteriorate the roof decking. Only roof jacks should be used which leave no nail holes.


Next month we will discuss the other five most common roofing mistakes.

Quote Of The Month

"It takes a long time to grow an old friend.”
John Leonard

Tip Of The Hat To:

Greg Cantrell
Living Stone Properties
232 West Crogan Street, Suite C
Lawrenceville, Georgia 30045

Warranty Recall Chek