DIY How to Recaulk Chimney Flashing

DIY Roof Repairs | February 23, 2021  | By: John Esh

Chimneys are a beautiful asset to a home or business! Most internal fireplaces require some type of ventilation and most often, chimneys are that ventilation.

How Do Chimneys Age?

The mortar, a cementitious material, secures the bricks in place and lasts about 25 years. Its lifespan can be more or less depending on the degree of harsh weather conditions. As the mortar is exposed to the sun, water, and fluctuating temperatures, it expands and contracts. While this is normal, as the mortar ages, it begins to form cracks. If left untreated, these cracks throughout the chimney structure and along the bottom near the flashing can cause leaking.

This chimney in particular is not causing any leaking, but upon inspection, it shows clear signs of aging. There are cracks in the bricks, cracks in the crown of the chimney, and some moss growth. We would recommend a mason coming to inspect the full integrity of the chimney. Our job as roofers is to make sure the flashing that transitions the roof material to the brick structure of the chimney is secure.

Steps to Recaulk the Chimney Flashing


This is Kevin with Joyland Roofing. We’ve got a chimney here that has some issues and I want to point those out before we take care of them.

The flashing looks to be in good condition; the main concern here is you can see this caulk is pulling away, leaving the gap there. We will want to go along and recaulk that.

It looks like there was an air bubble [in the caulk] that popped and that could be causing an issue. Like I said, the flashing looks good, we are just going to seal it up.

We are going to apply some sealant along this edge, fill in the hole that was formed, and secure this up.

You want to make sure that you use a really good silicone sealant, not just something off the shelf at Home Depot. The sun wreaks havoc with a cheaper caulk, caulk that’s not silicone.

Make sure that you try to stay smooth and consistent and get the nail heads covered with sealant too.

I am going to do the same thing on the front side. As you can see, there is some moss built up. Make sure to clean that out, along with any dust or grime that wouldn’t allow the caulk to hold.

Alright, as you can see, we went all along there with the sealant. I tried to stay as smooth and consistent as possible to avoid any other air gaps forming or gaps in the brick.

Get in touch with Joyland Roofing


Do you have questions? Would you like a professional to inspect or recaulk your chimney in southcentral or southeastern PA? Contact Joyland Roofing at 717-340-9565.

    Pennsylvania Home Improvement Contractor License (HIC) # PA124258