Chimney Flashing Photo and Description Page

Updated 11 / 2022

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Common Problems Flashing Kits
Lead Flashing? Flue Pipe Flanges
How to Spot Shoddy Work What do I do Now?
Example of Step-By-Step Copper Chimney Flashing Replacement
More Examples of Copper Chimney Flashing Replacement
Examples of Client Installed Chimney Flashing Kits


General information about chimney roof flashing

Below are a few examples of masonry work & chimney flashing kits I've made
Click on the thumbnails for a larger better view

From what I have seen chimney flashing is the most neglected area of a roof, if re-flashed at all. That is why this is such and important detail that you need to be aware of. More times than not it wasn't re-flashed during the last re-roof, which is against minimum Building Code. Here in Oregon they recently changed Building Code to indlude a cricket when ever reroofing is done, yet it is still rarely added to the job, since most homeowners do not know of this change to the code. Now you know.

Why a 2-Part Flashing is Needed with any Brick Chimney:
Chimney flashing needs a 2-piece; a step-flashing mounted on the roof deck integrated with the shingles, and a separate counter-flashing piece that is mortared into the gap between the bricks. NEVER cut into the brick! This 2-part system to allow for the movement of clay structure of the chimney and the wood structure surrounding it, caused by expansion and contraction as temperatures change throughout the day, and throughout the seasons from below zero to possibly 120 degrees. Also, as you heat up the chimney while in use.

The step-flashing gets nailed on the roof and lays up against the side of the chimney. Then the counter-flashing is mortared in the chimney (NEVER caulked) to hang down over the step-flashing to maintain a water tight seal, yet allow for this movement. This is why caulking this flashing is futile and will separate before long. If it is flashed properly, there should be no need to caulk it at all. Even in the corners. It needs to maintain this seal even with wind-driven rain and snow.

If you see black tar smeared on your roof, that is only a desperate temporary fix at best, and needs to be remedied quickly with proper rust-free flashing.

Common Problems With Roof Flashing:
Clearly the #1 cause of roof failure is faulty and or rusted out steel flashing; either from improperly installed, or complete lack there of, which I have seen all too often. If there is caulk on your roof that's usually a sign of a temporary leak repair and needs properly dealt with as soon as possible!

In my 3 decades of experience crawling up on several thousand roofs, seeing these details up close, I've seen how in most cases the Roofing Contractors did not re-flash many of these problem areas, which they were hired to fix in the first place. Let alone flashed the right way. Leaving the worse problem areas of your roof not resolved, so you've just been cheated out of thousands of dollars and made to suffer continuing stress. That's like having your car repainted without even washing your car first, or neglecting to sand the rusty areas for the paint to stick to a good clean solid surface. Resulting in the paint starting to peal off the first time you run it through the Car Wash.

I've done several tear-offs where I removed 2 layers of composite shingles over the bottom layer of wood shakes; in where the only flashing I found around the dormer was under the wood shakes, and of course it was very rusty and deteriorated. That means the last 2 Roofers had not bother to re-flash their dormer at all. I have yet to see evidence of a decent Roofer in this area (no joke). It really is that bad!

This means you are 99% at risk of being ripped off by any Roofing Contractor you're likely to encounter, so I have added this educational information to help arm you while interviewing potential Roofers. Since I do not sell roofing work, this infor is honest and unbias.

One of the problems stem from sheer ignorance, ethics, and lack of good examples to follow. Roofers come more from a hammer and nail Framer mind-set. Not from a sheet metal worker's perspective like me, so these areas of roofing escapes their private logic and confound them on how to manage wind driven rain, which all roofs will encounter.

Sadly ethical responsibility seems to be a thing of the past. I understand this is not just a local issue either. Improper roof flashing using just cheap steel is the standard across the Nation. This thin steel flashing will not even last as long as the most inexpensive low life-span 25 year shingles. Even if it does not rust all the way through it will cause unsightly rust stains down the roof, as seen in these photos.

To see more photos of this project click the link below

I have personally seen thousands of examples of this close-up. In most cases they will just bend the old counter-flashing out and slip the new step-flashing under it, and then just bend that rusty counter-flashing back down over it. When I've gone out of my way to question Roofers about this they say it is the job of a Mason to replace that flashing. This might be OK if a Mason was called out to do it. Or, at least make sure the Homeowners was made aware this roof job is not yet finished, and they need to call in a Mason to finish their work. I have come to learn most Masons do not know how to replace this flashing either, and really don't want to be bothered with it. It's way too much work and not worth their time to even bid such a small and dangerous job, so you as the Homeowner are left with no options. How does this make any sense?

 Even if this flashing is not rusty at all, it is not going to last through the life-span of the new roof. Even though Roofers are not willing to replace old flashing they are not likely to bother notifying you the Homeowner of these rust issues that still need fixed, so you don't have a clue that the roofing job was never finished. Then you'll start to notice staining inside from those leaks, which means serious damage has already occurred.

What's worse with this scenario is how many Homeowners are conned into paying to fully re-roofing their house because of these flashing leaks, instead of just replacing that flashing. These fancy talking Salesman are much more motivated to sell a whole re-roofing package to unsuspecting Homeowners to make that big ticket sale. All the while, knowing they have no intention to replace that defective flashing with something better.

Even if they do actually replace that flashing, they again will do this new work without the benefit of using a rust-free metal like aluminum or copper. Keep in mind how in most cases they will not bother to re-flash the problem areas as they had promised; failing to solve your actual problems.

This is the main reasons liability insurance for Roofers has been very hard to get and extremely costly for several decades. Costing around 500% more than any other type of construction work. That is very telling in of itself; demonstrating irrefutable proof of what I'm saying here. Numbers don't lie. Feel free to research this.

Most of roof flashing can be replaced without re-roofing the whole house (as seen above), but of course that is far less profitable for a Roofing Contractor, so that option is rarely discussed or considered as an option.  Each one of those Roofers know better, but they still do the same kind of crapy roofing work with that same cheap steel flashing, which they just tore off of your house. Seeing the evidence of it's failure time and time again.

They all know how the new flashing will fail in short order, but they just don't care. Isn't this said to be the definition of insanity: doing the same thing and expecting different results. Sadder yet is how they are only saving not more than $300 on the average reroofing by not using all aluminum flashing; which is about twice as thick and will not rust even if all the paint were to flake off decades later and still protect your house.

It's criminal in my mind. Can you imagine the amount of landfill that could be reduced if steel flashing was made illegal? Yet for over 30 years that I know of; Roofing Suppliers are not allowed to stock aluminum, stainless steel, or copper flashing by their Corporate Office.

If that were not bad enough; Instead of flashing areas with metal; they will often use the cheapest caulking sold; called mastic or asphalt tar. They just smear it around those problem areas. Mastic is just fibered tar with no UV protection. This will usually get the roof past their minimum required 1 year warranty the Construction Contractors Boards requires of any Licensed Contractor, but not lasting much more than that. Mastic will become brittle, crack, and peal away within a few years. If their work were to be inspected by a State Code Enforcement Inspector it would not be approved. They are not to use mastic anywhere on a roof. That is a clear sign this roof was not properly flashed right. Mastic is only to be used as an emergency patch to pacify the leak until a proper fix can be made. Although, it makes for a very messy clean-up when that repair can be done. The roofing in that area has to be replace after a mastic attack, as seen in these photos:

To see more photos of aluminum flashing click the link below

We know this to be a very common intentional crime of Roofing Contractors, since pretty much any roofer has seen the evidence of these all too common issues when doing a tear-off of an old roof; i.e. very rusty steel flashing on the roof and mastic failure with stained plywood underneath.  When they tear into a bad roof for replacement it tells a story: why this roof failed.  They would have to be complete morons to not see this clear evidence in front of their eyes.

Yet, they continue to ignore this evidence and do the same shoddy work, since in most cases they are not required to file for a building permit to replace your roof year after year; not having to worry about an inspector double checking their work. It has been this way for over 3 decades that I know of. If more than 15% of the roof deck needs replaced a Roofer is required to file for a permit. Yet that is still rarely done, since they know their work will not withstand the scrutiny of an inspection and you are the victim of this negligence.

What about Lead Flashing?
Some clients have asked about using lead for chimney flashing. Roofers like it, since they can cut is so easily with a box-cutter and form it by hand. It is some times use while the chimney is being first built, but I do not know how you could be able to get it into the mortar, when the more rigid and thinner copper flashing is difficult to quickly install before the mortar sets.

Another important issue with lead is how soft it is. I have seen numerous cases where animals had chewed holes in lead flashing.

My understanding is lead is harmful to the environment and people as well, so lead is ill advised. That is why they made lead illegal to use in gasoline almost 50 years ago.

Common signs of shoddy workmanship:
The most common mistake I see Roofers make when they have bothered to re-flash a chimney is to cut a shallow groove along the diagonal sides of the chimney to caulk a straight piece of flashing in, but these will not remain attached for long to the crumbly bricks and old mortar. Although that is not the worst problem; this sets up a fracture point for the chimney to crack and possible collapse in a minor Earth tremor. I have seen lots of evidence of this happening. So, keep in mind how if they do this to your chimney, they have permanently damaged your chimney. Where the only solution would be to rebuild the chimney down to the roof line with new bricks. If this damage has not yet been done to your chimney you need to warn your Roofer how you will require them to rebuild your chimney if they do this.

Shown in these photos below I was able to easily pull the long side flashing piece off without straining. Let alone the need for tools to pry it off. That is an example of how poor this sort of fix is. This was not an old install either. It was done less than 2 years prior to my replacement work.

To see 12 more photos of this project click the link below

Even high quality silicone caulk should never be used to attach counter-flashing, because it is just rubbery and adds no structural strength to your compromised chimney. Just as with the useless effort of tuck-pointing a chimney to make the mortar grooves look nice again; the new granulated caulk in such a shallow groove has only the old crumbling mortar to stick to, so it will simply fall out within a few years. These grooves need to be ground out a lot deeper than just 1/2" in order to have the upper and lower brick surface to adhere to, and only be filled back in with REAL mortar.  The groove needs to be at least 1.5" to 2" deep.  Anything short of that is a waste of time and money.

Aluminum flashing can be special ordered from a fabrication shop like mine, but of course that makes it just much more expensive than mass produced stock, but the time delay is the main reason roofers will not have it made for your house. If you bothered to have aluminum flashing listed int he contract, 9 times out of 10 they will still show up with steel flashing parts. If you are not there with a magnet to test and demand they get the right flshing, you just got screwed!

My Roofing web page at: goes into more detail about these terrible issue.  So don't leave without reading it over. It will help to save yourself a great deal of wasted cost and anguish down the road.

Can you make us a custom copper chimney flashing kit?

Here is an example of one of my first Client installed chimney flashing kits back in 2008:

I seem to be the only sheet metal shop willing to spend the time to work with Homeowners through e-mail to figure out these custom kits for them or their local installer to use. They are labeled and numbered in order of installation, precut, and bent to minimize customization needed at the job site. Below is some instruction and detailed photos to help give you a good idea of how to do this properly.

For more information regarding custom chimney flashing kits I make for our Clients across the Nation go to my Flashing Kits web page for more details:

What about chimney flue pipe flange and other flashing?
As you can see from our web site I can also help with many other custom flashing needs. Although, you may need to consider physical contact of the copper flashing with steel pipes and the detrimental effect it will have on the steel through electrolysis or galvanic corrosion. The steel will not harm the copper, but the copper will accelerate the deterioration of the steel. Stainless steel is compatible with copper. This chimney pipe for a wood stove in my wood shop corroded within a year and became unusable.

What If I Already Have This Kind Of Shoddy Workmanship On My House?
If you are are a victim of this all too common unethical business practice you can show your Contractor this web site. Then you should be able to deduct the cost of repairing your chimney and it's flashing even if you are going to do it yourself, plus the cost of cleaning off that black tar. I would encourage you to insist he has that tar removed and cleaned off by his workers to the point as if it were never there. That ought to teach him a lesson. It is messy work and solvents on your new roofing will damage the shingles and cause a terrible staining mess. If the contractor uses a solvent he'll then need to replace all the damaged and stained shingles at the same time.

Do not let them talk you into any other alternative, trying to minimize their costs. They will try to discredit me and say I do not know what I am talking about, but it is simple logic here they cannot BS their way out of if you stand your ground. Roofers will claim that it can only be done this way when the chimney was first built by the brick mason, but I prove here that is simply not true.

Below are examples of jobs I've worked on, that show these shoddy practices I've worked to repair.

Are there any other flashing shapes that may be better?
In my effort to seek a better product for my clients I had designed a special type of step-flashing with a pair of 45 degree bends, in stead of just a single 90 degree bend. This is an improvement over the standard right angle bend configuration normally used. This has several advantages and should not be difficult to fit into any type of roofing material.

Here are a pair of photos of this alternative flashing being installed by one of our clients:

Sealing around the corners of a chimney has always presented a problem to make sure it's water tight without the use of a caulk, which could fail sooner than the life span of the roof. It needs to maintain a seal even in the harshest wind storms and allow for the expansion and contraction with will differ than the wood structure. I have found this alternative shape helps in several other ways as well:

(a) navigates the rain water out away from the corners of the chimney a bit better.

(b) slows the water down and reduces upward splattering under the counter flashing.

(c) helps to be able to trim off the commonly compromised and damaged shingles nearest the chimney when replacing the flashing without a full re-roofing project, thus reducing the shingles needing replaced around the chimney.

(d) helps reduce scraping needed where the chimney meets the roof: old caulk or sloppy mortar work.

(e) makes it easier to cut the new grooves without needing to grind so close the the roof.

(f) application of an underlayment resting up against the side of the chimney for added protection is also made possible; without such risk of cracking that membrane needed with conventional flashing with such a sharp bend profile.

To see more photos of this installation follow this link:

Let me know if you need any special configuration and we'll customize your kit to fit.



Step-By-Step Copper Chimney Flashing Replacement
(you can click on each image to get a closer look)
Here is a link to download a PDF or DOCX file for this information to print out
(made for us by a satisfied client named Dominic M. Buccigrossi)

Old Flashing Removal:

You will have to wait for a spot clear weather, which can be hard to come by here in the Northwest, since the roofing needs to be torn up for a time to rip out the old rusty steel step-flashing. These photos show as I'm in the process of striping out the old steel step-flashing.

 These high density sealed cell foam cushion pad you see on the right are to sit on while I work.  It is not that I am so spoiled I need this comfort.  It is because it protects the roofing shingles from my work boots chafing the shingles, especially on a hot day.  It also is a safety issue, as it helps me be a lot more stable on the angled roof. Another added benefit is how it keeps me from wearing holes in my work clothes so fast. Shingles are very abrasive, just like sandpaper. It can be just an old common foam cushion, like a couch cushion w/o the cloth cover or camping pad.

A few parts of the original counter-flashing were still in the mortar joints, but had rusted so badly that it had broken off and still needed to be removed, so it does not interfere with the new copper flashing. These photos show close-up shots of the mortar grooves ground out in between the bricks in preparation for the new copper counter-flashing.  It is very important to not cut into the brick. Just the horizontal mortar joints. I use a 7.25" worm drive circular saw, with the flat work plate removed, so I can grind in tight to the roof and deep with these cuts into the chimney mortar joints. regular grinders will not work and are too dangerous to use.

These cuts need to be about 2" deep, which is half of the brick width. Enough to remove the old rusty flashing out of the chimney, but not further. Remember the bricks are only 4" wide. You must be careful with this or the chimney could collapse under the weight of the bricks above these cut lines. So far I've not had a chimney collapse from this extraction work, but I imagine it could happen. Especially when I've see old mortar that was so rotten that I could dig into it with just a wood pencil, so it's best to be mindful of that possibility. Especially if the mortar is that soft and crumbly. Standard bricks are just 4" wide, so that still leaves at least half of the old mortar to continue to support the weight of the bricks above these cuts while I am working on this. There could be a full ton above pressing down on these cuts.

As you can see it makes a huge dusty mess that can be dangerous under foot and harmful to your lungs.  You'll need to wear a good resperator filtered face mask and safety goggles while doing this grinding work. This dust will settle in your hair and you'll not be able to drag a comb  through it (ick), so it is best to wear a hard hat or a bandana. It will wash out just fine with ordinary shampoo, but it will seem far dirtier than you have ever known your hair to be.

Step Flashing Installation:

This shows the 20oz solid copper sheet metal base step-flashing in place, nailed down and hidden under the shingles on the sides. You should use 1.5" copper roofing nails.  I also add some clear caulk in the corners and the copper is folded over these corners to shield the caulk from the Sun. When this is complete there should be no visible nails or caulk. Roofing is all about hiding the fasteners. I was careful enough to not need to replace some of the shingles around the chimney, but that is not common. You should have some matching shingles handy to replace any damaged shingles from this re-flashing work.

Counter Flashing Pre-fitting:

The image on the right shot show the counter-flashing test fitted in the grooves and custom shaped and set into place before it is going to be mortared in. Some customizing will be needed. Make sure this is all prepped and ready before mixing the mortar, as you will not have time to make many changes after that, so this is an important step.

There should be a 1/2" gap between the counter flashing bottom edges and the shingles to allow for the expansion and contraction of the chimney in relationship to the wood structure of the house. You will not want this to bind up and get bent out of shape if it is set too close.

When you are ready mix about 1/2 gallon of mortar. The counter-flashing is then quickly mortared into the gaps I had cut in the sides of the chimney. I first shove the mortar into a joint with mason tuck pointing tools starting with the bottom sections working my way up only one grove at a time shoving the flashing into the mortar as fast as possible before the mortar quickly sets. The dry bricks will such the water out of the mortar within seconds, so be ready with each piece as you work your way up.

The wider top and bottom joints are especially hard to do quick enough before the mortar gets too stiff to be able to press the whole counter-flashing piece in. I often have to tap it in with a rubber mallet even on just a small single flue chimney like this. You may even need to spritz these groves with a water bottle before shoving the mortar in the longer groves to keep the mortar from setting up too quickly, or use 2 shorter pieces to install one at a time. If it does not work out you will need to scrape out the stiffened mortar and start over, so don't try to force the metal in the grove and denting it up and ruining that piece.

As you see here this chimney has just a simple horizontal tray along the top side. It is best to have a cricket or saddle made to divert the rain water and debris out to the sides of the chimney. It is a bit trickier to make and install, but makes a big difference. It should be made to the same roof angle out to the sides. Not very simple math to calculate t6hese angles. It should also have a wood support under it, or it may get dented when some other worker is up there and did not know it was just hollow underneath.

This is the chimney from the back side. It is important that there is this two part flashing with a good 1/2" gap along the bottom edge of the counter-flashing, since the chimney is founded in the floor of the basement, and it will be expanding and contracting differently than the wood structure of the house, so it needs to be able to move in relation without binding up. As listed above, it would have been best to have built a cricket to divert the water and debris off to both sides of the chimney, but that would have added another $150 to the cost of this flashing project. Since this was just a rental I knew she was not wanting to invest any more than she had to.

The worm drive saw seen in the roof valley below to the right is what I use to grind out the mortar joints. The base plate has been removed to be able to get in close the the roofing. Side motor saws will work fine on one side, but the motor would be in the way on the other side. The grinder tools they sell do not have a larger enough blade to get in deep enough for this work and too thick to cut above and below the old metal flashing that has to be removed.

The shingles are wet from hosing down the mess after I had broomed of the bulk of it. A plastic and or a wire brush with hydrochloric acid can be used to clean up left-over mortar smears to leave a nice clean job.  The acid will need to be diluted, or it will be too caustic to the worker for use.  One part to ten parts water is plenty strong still.  It is also helpful to clean the mortar off of the shingles.  Be sure to use protective rubber gloves.

Buyer Beware:
Back in the mid 90's I've seen other contractors charge over $750 just to counter-flash a single flue chimney with cheap steel. That was over 25 years ago, so with inflation it would be more like 3X that amount now, or well over $2k. This was back when copper was less than half the cost and gas was only $1.30 a gallon. I believe the cost these days should not be more than $1k to re-step-flash and counter-flash a single flue chimney with parts and labor using 20oz copper. Perhaps more if they are adding a copper clad cricket. To use cheaper steel or even aluminum would save them only about $150 these days, which is only 10% of the cost of their work. Even if they would make you pay an extra $300, it is best to have them use the thicker 20oz copper. If they tell you they can only get 16oz copper, then you know not to hire them, because they have already lied to you or just too stupid to do the job.

You will even need to double check their materials before it goes in, or you are likely to get a thinner copper or just painted steel that sort of looks like copper used instead. By then it is too late. I have several seen contractors use a steel or aluminum sheet metal that was just painted to look like untarnished copper far too often. If it attracts a magnet at all, it is not copper. I've never seen copper plated steel sheet metal, so do not fall for this ploy either. The Sun will bake off that thin layer of paint and it will rust within a decade or so.

One of the only ways you can know for sure the right material is used is to have me make up a solid copper flashing kit for you, and have them use that instead. Then discount you for the difference in cost.

It is a sad state of affairs, but it seems few experienced roofing contractors even know how to do this right, or are willing to try. The basic logic of rain management seems to escape them. Even when they have an example there in front of there face to see how it is to be done on most chimneys they come across.

You would do well to compel your local roofing contractor to read over these web pages and finally learn their craft.  They may take offense to this suggestion, and especially this web page, but that is very telling of their lack of character and you would do well to take that as evidence they cannot be trusted to have your best interest in mind and you should not hire them. The overwhelming evidence here shows this is a simple fact of reality that cannot be debated. Here is a Word 'doc' file to print out with the recommended list of tools and more detailed  instructions:





Helpful Roofing Information
For some valuable advice with regards to roofing and rain management issues check out our:

(a) Gutter Installation
(b) Gutter Debris Protection Options
(c) Roofing Quality Standards
(d) Moss Control & Treatment

web pages for answers and solutions that could save you thousands of $ and a great deal of anguish.

If you do find this information very helpful, feel free to send us a $ tip for the assistance we so freely have published on the web here for your benefit, like you might tip a waitress.  Heck, send us a gift certificate for a candle lit dinner for two.


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