How To Understand The Layers Of Your Roof: Flashing

How To Understand The Layers Of Your Roof: Flashing

Flashing is not flashy. Roof flashing is a catch-all term for some vital parts of the many components of your Grand Rapids-area home’s roof. It helps protect your home against Michigan’s worst weather, all year long. 

Metal Flashing

When roofers refer to flashing, they are usually talking about thin, flexible metal sheets used to bridge gaps between different materials. Consider your roof: chimneys of stone and brick must meet roofs of wood, shingle, and metal. 

All materials expand and contract as temperatures change. The problem is — using your chimney as an example — wood and stone thermally expand at different rates, so they must be built with tiny gaps between them. 

To cover that gap, roofers install metal flashing. This prevents water from seeping into the sheathing and onto rafters. Metal flashing is also used in valleys, to prevent water pooling and saturating sheathing. 

You often see metal step flashing from your yard; it embraces the first few bricks above the roof line, around your chimney. 

Flexible Flashing

Curb flashing is used around skylights of extruded metal that must sit within rafters of wood. As with your chimney and roof, the skylight changes size and shape at different rates than the rafters, so curb flashing — flexible plastic or rubber — is installed to prevent leaks. 

This material can also be used around kitchen and bathroom vents and in other places. You might see a bit of curb flashing if you have a keen eye, but much of it is hidden beneath your roofing material

Rubber Boots

Some roofers lump the rubber boots used around sanitary stacks in among the general category of flashing. These donut-type sealants prevent water leaks around the roof piercings above bathrooms. These are very visible but easily overlooked when gazing up in admiration at your beautiful, well-maintained roof. They are almost always black or another dark color, to blend into your roof’s general profile. 


Metal flashing, curb flashing, and rubber boots are not glamorous. They are necessary parts of your roof, and must be in good shape for your roof to stay intact and shed water. Roof leaks are common when flashing fails.

During full roof replacement, your roofer removes most flashing and evaluates any that can be reused, replacing aged-out items. 

Moore and Sons Roofing provides homeowners in the Grand Rapids area with complete roofing services. Contact us today so you can sleep better tonight, knowing the roof that protects your home is protected by us.

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