Ensuring a Low Slope is Watertight

From time-to-time we install shingles on a roof that has flatter areas where the slope or pitch doesn’t conform to the rest of the roof.

We recently converted a roof from cedar shakes to asphalt shingles where there was a low slope area between two steeper pitch sections of the roof.  In order to deal with the water runoff from the steeper slopes, we installed self adhering SBS membrane to this section.  The membrane will also prevent the ice and snow from backing up in this area, which is always a concern in our climate.

We start by applying ice and water shield to the entire area including the steep slopes on all three sides.  This application ensures that all sides of the roof draining into the flatter area are water tight.


View from an upper roof down onto the flat valley area

Once the ice and water shield is in place we apply the self adhering SBS membrane (cap sheet) to the valley area and up the side of each slope that drains onto this part of the roof.  The membrane is overlapped on the down slope to prevent any chance of water penetration.


The SBS cap membrane is applied well up the sides of the steeper slopes

The bottoms of the steeper areas are shingled in a picture frame so that all sides that drain onto the new membrane which will direct water correctly.  You can see that the slopes facing the metal valley are framed to direct any runoff into the valley and down to the low slope, membrane covered area.


Shingles are applied to direct water flow to the metal valley and SBS covered area

Finally, the slopes facing the SBS area are shingled in to finish this part of the roof.


The completed low slope area

Welcome to our Blog!

Hello and welcome to our blog.  It may seem odd for a roofing company to have a blog, after all, a roof is a roof and what is there to write about? Well, lots!

In our series, we will explain the importance of the different components of a roof and how products and installation both can make a great difference in how well your roof performs and how long it will last. We might even throw in a recipe for tonight’s dinner or a tip on how you can remove that annoying stain on your ceiling.

Each month we will share our knowledge of a different piece of the roof and how each piece affects the overall longevity of your home.   We will explore, individually, the different products that we use and their effectiveness as well as explaining why we use each piece to ensure a quality installation that meets or exceeds building code.

If you have questions that are not answered here, call or email us and we will be happy to answer them for you.  We can arrange an appointment with you for a free detailed quote to reroof your home.

You can depend on us for an accurate quote, quality installation and great after sales service.  Check out our rating at the Better Business Bureau and at

Next month we will look at metal components, why we use them and their installation.