The Importance of Flashing in Your Home

In rainy Oregon, it is crucial to protect your home with the proper roofing materials to keep moisture at bay. 

Flashing is critical in keeping moisture out of your home, but it is one of the elements that we find to be missing the most often during a home inspection. 

Why does flashing do and why is it so important to have on my home? 

What Does Flashing Do? 

While shingles are the most commonly talked about component of a roof, flashing is equally important. The purpose of flashing is to seal holes and gaps in materials with a water-proof strip. 

The weak points of your home’s roof are where flashing is placed – almost always places where two surfaces come together. This is because where materials come together, there is almost always a crack, which allows moisture to get in and also makes it harder for it to escape. 

Flashing is directionally placed to direct water away from the roof, channelling water droplets downward and off the roof. 

Why is Flashing Important?

Homes are made with less air leakage rates and more insulation, which means that flashing is even more important. This is because if water does get into the cracks of a home, it will not evaporate as quickly, and will cause rot and mold. 

Because flashing is made from water-proof materials – such as aluminium, copper and lead-coated copper, lead, galvanized steel, and PVC – the water is repelled and is driven away from the home.

Where Should Your Home Have Flashing?

Flashing should be placed anywhere that there is a joint or meeting of materials, such as:  


  • Chimneys are one of the biggest penetrations (or holes) in the roof.
  • They need to be sealed properly to prevent erosion from rain and leaks. 
  • Flashing is attached on the side to direct water away so it doesn’t collect at the base.


  • A valley is where the sloping parts of a roof meet, creating a dip where water and snow can collect. 
  • Water is directed off the roof into the valleys, so flashing is important to create a quick and durable channel for the runoff to escape. 


  • Skylights are not on every roof, but they are another gap in the roof where water can enter the home if it is not directed away. 
  • Flashing is typically installed on all sides of the skylight, in addition to other sealing materials. 


  • Any other vents in the roof or walls have flashing, to deter water and increase the effectiveness of the seal. 
  • Flashing protects the sealant used from the elements as well. 

Don’t Skip the Flashing

Often when roofers and repairmen are in a hurry or don’t have as much experience, they may use other materials in place of flashing. When inspecting homes, we often see roofing tar and caulk used in the place of flashing. 

Roofing tar is more common, because it is convenient for roofers to use while they are already installing a roof. However – it will dry out and crack over the years. These cracks can be so tiny that they are easy to miss, but water can seep through easily and cause rotting and damage to the home. 

Caulk similarly will crack and dry out eventually, from the changing weather and constant elements. It just isn’t as strong as metal, and will give way to water if it is not replaced and resealed frequently. 

Guest blog by Bryant Wilkins of Advance Home Inspections in Baltimore, Maryland.

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