This is a more detailed look at the flashings used in your roof installation. For more information about the rest of the roof, check out this guide on the best roofing materials for your home.
Flashings are a key component of your roof. Not only must you make sure all of the flashings below are installed correctly on your roof, but you also must make sure they are the right quality (and hopefully painted to make your home look good).
The word flashings is a big word, as it technically is used to describe any metal used on your roof. This includes:
- pipe flashings
- valley metal
- drip metal
- step flashings
- apron flashing
Flashings are by far the most vulnerable points on your roof since they are covering holes in the roof or joints where the roofing meets something else. This is the most critical part of the roof for your roofers to install right. Most of the leaks we encounter on older roofs are due to flashings that are deteriorated or installed improperly.
Because a roof is supposed to last a minimum of 25-30 years, we highly recommend that all flashings be replaced when you get your home reroofed. Even if all these flashings already exist, they are often filled with holes and are beginning to break down. The only way to ensure your flashings don’t leak in the future is to replace all of them.
These seal around the pipes that stick up through your roof – usually a bathroom vent or Radon vent of sorts. These flashings are critical to a roof’s performance since it is literally covering a hole in your roof. If this pipe flashing fails because of a material or installation defect, water can go straight through your roof into your attic.
The classic type of flashing to use on these are a stainless steel base combined with a black rubber ring that seals around the pipe itself. The only problem with these are that the rubber gets baked in the sun and frozen in the cold. Over time this rubber becomes brittle and will crack. What we recommend is an all-metal flashing that wraps around the hole pipe. Not only will these flashings last forever (no rubber to wear out), but you can also paint them to match the roof and they look great.
A valley in your roof is anywhere that 2 horizontal planes meet each other, usually at a right angle. This creates a seam between the sheathing where you have to blend two sides together. This is an inherent weak spot in a roof. Since plywood is flat, there will be a sharp corner in the valley, and when you lay felt and shingles over the top it can create an air pocket between the plywood and shingle. If anything is put in the valley (like someone’s foot, a snow shovel, etc) it can break through the shingle and leave a huge hole leading directly into your home.
Since all the water on a roof will run to the valley, this can end in huge problems on the inside of a home. This is why we highly recommend installing valley metal in the valleys. There are two different ways to do it, either a concealed valley metal (works well with the lighter weight shingles), or an exposed valley metal that should be painted to match the roof. Exposed valley metal is necessary when using some of the heavier weight shingles that you can’t bend through the valleys.