Prolong Your Roof Life! Repair It Yourself!

Fix that leaky chimney or flashing!

As having spent a few hours on my roof today to remedy an issue with our chimney I have to share that in a previous life, I worked as a roof inspector for quality assurance. We were a third-party entity that provided an RFP to roofing contractors, then enforced the SOW onsite. The end-user hired our company to represent them in all roofing matters, so for the purposes here, we were the end-user customer.

The way a roofing system works is there are several layers in this case for a ply system and aggregate roofing material on top. We provided what the system would be, the materials it was to be made of, and ensured that it was installed per our specs - which in some instances exceeded the manufacturer's specifications.

The underlayment goes down, then the roofing system on top of that, then the metal flashings, and if you're lucky - it includes the finishing roof cement, granules, and silver paint.

Repaired Chimney Flashing

Finished Chimney Flashing Repair
Finished Chimney Flashing Repair

Fixing Flashings

On top of the roofing system, when you set metal flashings at every roof system penetration, you need to ensure that the water barrier is still intact. Unfortunately, in a residential setting, most roofing contractors do not finish the flashings in the manner in which we do in a commercial setting. What normally happens in a commercial setting is that the contractor sets the new metal flashing down on top of the roof system using tar and/or mastic (roof cement), complete with granules embedded and silver paint.

So today, I was informed I needed to get up there and fix it... since we are expecting rain. So I go up, and it is readily apparent where we needed some help at the chimney. So here is how you do it:

Supplies:

  • Brush
  • Broom
  • Rags
  • Nitrile gloves (more than a pair - this stuff gets messy, mastic is toxic)
  • 2" putty knife/spatula
  • Mastic - if you are expecting rain the same day or so get the 'wet' version.
  • Webbing of some sort: the mesh used for drywall repair or fiberglass, or similar
  • Granules: absorb, kitty litter, or similar
  • Silver Paint; reflective roof paint preferred


Supplies

Click thumbnail to view full-size
Mastic - standardMastic - wetDust BrromPush Broom - I took this opportunity to clean all of the pine needles off of all of the valleys.1-1/2" to 2" Putty KnifeRoofing Granules; kitty litter, oil absorbing, etc.
Mastic - standard
Mastic - standard
Mastic - wet
Mastic - wet
Dust Brrom
Dust Brrom
Push Broom - I took this opportunity to clean all of the pine needles off of all of the valleys.
Push Broom - I took this opportunity to clean all of the pine needles off of all of the valleys.
1-1/2" to 2" Putty Knife
1-1/2" to 2" Putty Knife
Roofing Granules; kitty litter, oil absorbing, etc.
Roofing Granules; kitty litter, oil absorbing, etc.

How to do it:

  1. Clean the debris from the area with a brush or whatever tools necessary.
  2. Using a 2" putty knife or similar, spread the mastic along the area to be repaired. about the width of the putty knife, making sure there is a proper seal; no holes above the membrane.
  3. Add the granules onto the mastic once completed, patting them into the mastic - not just sitting on top.
  4. Paint the whole line of mastic/granules silver.
  5. Do this at every area for repair, remembering that water flows downhill, including around all of the flashings*.
  6. Check the flashings welded areas and rims, sealing any area that has come apart. Notate that you need new flashings, replace at next roof repair opportunity.

This should get you through the worst of it! Let me know how it goes!

Photo Gallery

Click thumbnail to view full-size
Finished Chimney Flashing RepairChimney Flashing; prior to any repairMastic applied, you can see the mesh I placed - you cover it with another coat of mastic.After the mastic is applied, add the granules - make sure you press them into the mastic to ensure retaining the granules.Let it set up a bit... at least a half hour or so, then paint it with the silver paint.Seen from the ground, you can see the flashings were rusty and unprotected; with no mastic.Bare flashing; don't think your roofer skipped something on you, this is commonly done in a residential application. Homeowners don't know enough to ask for them.You can see the top edge of the flashing where the metal is separating, possibly leaking water down below, or under the roof system.As a temporary solution, I applied the mastic here as well, then painted the entire flashing - mainly as a new starting point for me to monitor from here on out.The larger flashing, you can see here they had sealed it, and painted it silver, but the seal had broken.A closer view of the broken seal.I applied more mastic, then repainted the whole thing as the other flashings.Newly painted/sealed flashings from the ground. From this vantage point, any rusting or compromised flashings should be readily visible.
Finished Chimney Flashing Repair
Finished Chimney Flashing Repair
Chimney Flashing; prior to any repair
Chimney Flashing; prior to any repair
Mastic applied, you can see the mesh I placed - you cover it with another coat of mastic.
Mastic applied, you can see the mesh I placed - you cover it with another coat of mastic.
After the mastic is applied, add the granules - make sure you press them into the mastic to ensure retaining the granules.
After the mastic is applied, add the granules - make sure you press them into the mastic to ensure retaining the granules.
Let it set up a bit... at least a half hour or so, then paint it with the silver paint.
Let it set up a bit... at least a half hour or so, then paint it with the silver paint.
Seen from the ground, you can see the flashings were rusty and unprotected; with no mastic.
Seen from the ground, you can see the flashings were rusty and unprotected; with no mastic.
Bare flashing; don't think your roofer skipped something on you, this is commonly done in a residential application. Homeowners don't know enough to ask for them.
Bare flashing; don't think your roofer skipped something on you, this is commonly done in a residential application. Homeowners don't know enough to ask for them.
You can see the top edge of the flashing where the metal is separating, possibly leaking water down below, or under the roof system.
You can see the top edge of the flashing where the metal is separating, possibly leaking water down below, or under the roof system.
As a temporary solution, I applied the mastic here as well, then painted the entire flashing - mainly as a new starting point for me to monitor from here on out.
As a temporary solution, I applied the mastic here as well, then painted the entire flashing - mainly as a new starting point for me to monitor from here on out.
The larger flashing, you can see here they had sealed it, and painted it silver, but the seal had broken.
The larger flashing, you can see here they had sealed it, and painted it silver, but the seal had broken.
A closer view of the broken seal.
A closer view of the broken seal.
I applied more mastic, then repainted the whole thing as the other flashings.
I applied more mastic, then repainted the whole thing as the other flashings.
Newly painted/sealed flashings from the ground. From this vantage point, any rusting or compromised flashings should be readily visible.
Newly painted/sealed flashings from the ground. From this vantage point, any rusting or compromised flashings should be readily visible.

Me up on the roof.....

How did it go?

How much roofing experience do you have? How was was this for you?

  • A lot, this was a piece of cake.
  • A bit, I didn't find this intimidating at all.
  • A little, I was slightly intimidated - and afraid of heights to boot!
  • None, I was terrified. But I did it, ladder and all!
  • None, and still none. I got to the part where I called the roofer and had them come fix it temporarily!
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