Slipping (Sticky) Roof Membrane Under Existing Step Flashing

March 9, 2023

A three-foot stick can hold a section of step flashing out of the way while you work the membrane into place.



Covering a roof with peel and stick membrane is a relatively straightforward task: begin at the bottom and cover the roof, sticking the membrane down as you go up.

Slipping the sticky membrane underneath step flashing—without it sticking to the roof, can make the straightforward a little curvier.

The solution? Use thin starter strips to secure the edge.

But how can you simultaneously hold up three feet of step flashing?

With a wedge. A triangle shape will allow you to slide it under the step flashing tight to the wall without bending the metal.

When the wedge is in place, cut a thin slice of roofing membrane and peel back the release sheet on the top corners.

Slide the peel and stick against the wedge, rolling the edge up onto the stick but not pushing the edge onto the wedge. 

It is a delicate dance between positioning the membrane where you want it and removing the wedge when you need it.

With the top of the membrane strip positioned, pull back the release paper and position the rest of the membrane strip.

Notice that Lynn is bending the peel and stick up the side of the wedge stick. 

Finally, pull out the stick as you slip the far edge of the membrane under it. 

Now you can get to the easy part of filling in the big spots.


—Lynn Hayward is a builder and remodeler in Northport, Maine


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