Should Flashing Be Replaced or Re-Used When Installing a New Roof?

I knew comparing bids from different contractors was difficult for homeowners that don’t do it everyday, but I didn’t realize HOW frustrating it truly was until my grandmother in California sent me three estimates she had received from local roofing contractors and asked me to tell her which one she should go with.   This is what I do for a living and I couldn’t compare one to another as each contractor was recommending a different scope of work, different specifications and different products in each proposal.  (Have you ever felt frustrated comparing estimates? This article here: “How to compare estimates” might help also!)There was absolutely no way to compare “apples to apples” between the three bids and I came to the stark realization that this is the quandry that each of my customers are faced with, here in Hampton Roads, Virginia, when I present them with a proposal.  I feel for them.

One of the biggest differences between roofing estimates that homeowners will receive is that one roofing contractor may have included replacing the flashing in his proposal while another roofing contractor may be re-using it.  This could be a huge difference in the amount of work being performed and result in a very large price difference!

But is the price difference worth the extra work?

First we have to figure out when it comes to roofing what is flashing?

Flashing refers to thin pieces of sheet metal installed to prevent the passage of water into a structure from an angle or joint.

On a residential home you should expect flashing in the following areas:
1. Where the shingles terminate against a vertical wall, such as a side of a second story or a dormer or chimney.
2. Any protrusion in the roof such as a plumbing vent pipe, HVAC vent or stove pipe, or solatube or skylight.
3. Sometimes in valleys where two roof slopes meet.
Here’s a good video that shows how the shingles, flashing, housewrap and siding all fit together:

The flashing is nailed to the roof and it is critical that the nail placement is proper or it will result in leaks. In fact, after diagnosing roofing leaks for 15 years, I can tell you that roofs rarely leak in the field of the shingles, 90% of the time they leak where the roof “stops, starts or changes direction” – which means most of the time the problem is with a flashing.

This roof leak in a Poquoson, Virginia home was from a pipe collar flashing.

This brings us to the question, “if the flashing wasn’t leaking on the old roof, why shouldn’t we re-use it when the shingles are replaced? “The short answer is “you can” and it’s possible there will be no problems. But re-using the flashing can’t be considered a “best practice”, even though it is allowed by the building code it is NOT recommended by any shingle manufacturer.

Good Graphic by Extreme How-To Website

Why don’t roofing shingle manufacturer’s recommend re-using roof flashing when replacing a roof?

The short answer is, “because the nails don’t always go back into the same holes they were in originally”.   Practically, however, when you’re replacing a 15-20 year old roof, you don’t know:

1. How the original flashing was installed. Was it nailed properly?

2. Has the flashing been repaired in the past?  What kind of repair was made?   We’ve found everything from pinholes repaired with caulk to cut up beer can aluminum as repairs.

3. How many times the flashing has been re-used over the lifetime of the house?  Does the flashing look like swiss cheese it’s been nailed down so many times?

The bottom line: The only way to ensure the quality of the flashing is to replace it with new flashing and install it properly when the roof is replaced.

Believe or not, this idea got a LOT of resistance by local roofing contractors here in Hampton Roads, Virginia when I first proposed it.  One of the most common things I heard was:

“I’ve been installing roofs all my life and I’ve never had a problem with re-used flashing!”

This was said by a 30 year old roofing contractor. I pointed out to him that if he’d been working in the industry since he was 18, he had only been installing for 12 years and the very first roofs he worked on as a laborer hadn’t even made it through half of their lifespan yet.  Also, I asked him how many roofing contractors he had worked for.  When he answered 5, I pointed out that if any of the roofs he worked on had developed leaks, how would he have ever known if the customer couldn’t find him?

 The Proof in the Pudding:

Because I encountered so much resistance against recommending that homeowner’s replace the flashing when a roof was replaced – even by my own employees – I started an experiment: on a large white board in our office I wrote on the left side of the board :

“Callbacks because of leaks & cause of the leak”

On the right side of the board I wrote:

“Number of days without a leak on jobs where all flashing and components were replaced”

(I have never heard of another roofing contractor doing this, so I might be the only contractor with this data).

It didn’t look anything like this. I don’t wear a suit at work. My employees don’t wear suits either. Like the whiteboard, though? You get the idea. Work with me here, people.

Over the next two years I gave homeowners the option of re-using or replacing flashing and vents on every proposal.  Some owner’s did replace the flashing and others chose not to.  At the end of two years we had quite a list on the “Callback” side of the board.  What was the revelation?


What about the side of the board that kept track of the days without a leak on jobs where flashing was replaced?  We were over 700 days without any leaks on jobs where all the flashing and components had been replaced.   At that time we stopped keeping track.

The “proof was in the pudding”.

If you found this article helpful, here are some more roofing articles:

This post authored by
Jim Hicks.

Jim Hicks Home Improvement serves Yorktown, Virginia Beach, Newport News, Williamsburg, Chesapeake, Norfolk, Hampton, Suffolk, Portsmouth

Contractor, Home Improvement, Remodels, Additions, Kitchen, Bathrooms, Shingle Roofs, Slate Roofs, Siding, Windows 757-706-3110

Disclaimer: All images, unless otherwise noted, were taken from the Internet. In the event that there is a problem or error with copyrighted material, the break of the copyright is unintentional and the material will be removed immediately upon request.


  1. replacing eve boards that are rotten
    Should I also go ahead and replace the metai flashing

    • If you mean the drip edge I would inspect it to see if it’s still in good condition or not. Also, what caused the eave boards to rot? Was it bad drip edge?

  2. Jim, how do you reflash a double wall chimney pipe?

    • If we are talking about a sheet metal chimney pipe, it should have a flange piece. If that piece is damaged on unusable, any sheet metal shop can fabricate a replacement.

  3. My crew just installed a new roof and they renailed flashing down that didn’t have nails before They said since it was not new and we reroofed the flashing would leave a gap where water can get in It looks like crap and the homeowner is refusing to pay until its corrected Some of the nails are not even touching the metal strip of flashing they are nailed into the shingles I didn’t think that was the correct application but they soy it was

  4. I’m trying to decide what kind of material have my roof made out of. I didn’t know that flashing could help keep it from leaking! It would be so nice to have a roof that I don’t have to worry about too much.

  5. We recently had shingles replaced on a 328 unit townhome community here in Denver Colo. The general contractor (they didn’t hire a roofing company) hired
    a group of multi-state roofers, who, in the short period of 5 weeks completed half of the community. Doing so, they ripped up the siding, where it was tacked down by tack strips. They removed the tack strips, about 5″ metal to keep the siding attached to the wall. They haphazardly used other material to tack down the damaged siding, and left the property. With re-siding the community, we’re left with a real mess.

    Do all roofers just destroy the existing siding when replacing shingles? Seems expensive and not professional.

  6. I had a new roof put on my house. First heavy rain- and rain was coming out of the ceiling of my back room. The roofers were paid by my insurance co. to replace the skylight but they didn’t. After many excuses and me reporting them to the state I get a letter telling me case closed get an attorney. ( I have all my paperwork) It’s a 2×2 skylight, one estimate was 750 the most recent 1,690.00!?? I’m so annoyed. Im a single woman with a tarp over my skylight for a year now after paying 8000+ for a new roof.
    Thanks for listening.

Leave a Comment