My brick chimney is on the side of my house. I was in the attic and I noticed water marking right behind the chimney. I am assuming this is because of the flashing.

I am a do it yourselfer and I have easy access to the roof. I plan on reshingling the roof in 3-5 years, so this can be a temporary fix or if it is easy to do I can redo it when it comes time to reroof.
I have zero experience. I don't have a brake to bend flashing. Is this something I can do solo?

You can do it with a cheap harbour freight grinder and hand seamers.

https://www.familyhandyman.com/roof/installing-chimney-flashing/view-all/

https://www.lowes.com/pd/BLACK-JACK-4-75-Gallon-Fibered-Waterproofer-Cement-Roof-Sealant/3009895

Would this work?

Your next roofer is going to have a fit if you smear all that shit on your chimney.

Im a big advocate on diy, but i would hire the flashing out.  It shouldnt cost that much for one side of a chimney.  If you end up doing it yourself, you shouldnt have to use more then a tube of caulk.

I've only seen lead used for chimney flashing. You can buy it at Lowes or Home Depot, but you need to ask for it as they keep it behind the contractor's desk because people steal it.

It's very easy to work with the lead, but go slow so you don't rip it.

The worst part is taking out the old flashing and grooving the mortar joints to accept the new flashing. An angle grinder does a nice job of that though.

Also, take your time when working the lead under the roof shingles. "Be the water" and be sure to install the flashing so water can't get underneath it. Give yourself plenty of length under the shingles. Removing some shingles and renailing them as you flash will make life a lot easier.

With that said, if you think you know where the leak is, a little mastic/roofing tar/roofing caulk spread around can do wonders. It can be a pain to remove/work around down the road, but isn't that bad provided you're not trying to do it on a 90 degree day.

Use copper flashing for a masonry chimney.

Portland cement )in the mortar) EATS aluminum and steel quickly.

Copper or lead not so much.

Examine the slots in the brick.
They need to be large enough for the copper flashing AND the lead used to lock the copper in the groove.

It is a lot easier to learn how to solder copper flashing than 'burning' lead flashing.
There are some ways to minimze the need for soldering but it is still useful to be able to do is on many installs.

You need flashing and counter flashing.
They should NOT be in the same masonry groove to work most effectively.

Some clamps and extra pieces of wood will allow you to hand (and hammer) bend copper flashing to shape.

Since the largest piece is usually on the up-roof wide of the chimney, and cannot be seen from the ground appearance is not usually very critical.

I strive to use a single copper piece that wraps around the chimney sides here to eliminate all seams and joint.

considering i will be my next roofer the way my finances are going, im really not to worried. an angle grinder with a wire brush attachment would probably remove all of it with little effort. i might try and caulk it.

If you can use caulking to temporarily stop the water, it will be a better seal than the roof cement. Roof cement has its place, smeared all over a chimney isn’t it, and unless you use a fabric or mesh it’s not going to last long anyway and will look hideous. If you want to, send me some good pics of around the chimney I will see if I can diagnose and give you suggestions how to fix. Email is [email protected]

The best use for roof cement is to hold pieces of shingles on the surface.

Is there anything that stands out as being in disrepair?

Runoff from rain on masonry eats anything except copper.

Aluminum very quickly.
Galvanized steel a little slower.

Yes, scrape off the old caulking/sealant from the counter flashing. It’s definitely loose or open. Re-seal with a good 1 part urethane and make sure to tool it out good so that your getting proper adhesion. The rest of the mortar on the chimney, step flashing and counter flashing looks good from what I can see in the pics. The very bottom exposed nail could also be hammered back down and a small amount of caulking applied to cover the nail head. Again tooled down so you know it’s stuck.

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The caulk on the top of the flashing WIL fail sooner than anything else.

Put some correct counter flashing into slots in the mortar with lead caulking (strips driven i) to hold it.