Rain, water, and common chimney issues in #Spring

Leaky chimneys. Raindrops in the fireplace. Water pooling on the tops of the chimney cap.

It’s that time of year — when we still have snowy days, but start seeing mostly rainy ones. It’s usually when homeowners take notice of the performance of their chimney, already one of the most taken-for-granted parts of a home.

The chimney performs several vital functions. Their simple appearance misrepresents their complex construction and performance requirements, and a chimney deteriorated by constant exposure can be a potential safety hazard — such as direct contact with water and water penetration!

This blog post is designed to address some of those issues. Keep in mind: water can be introduced to a chimney from other areas of the home.  Damaged gutters, overflowing gutters, downspouts dumping water near or on the chimney, and even gutters that are not sloped away from the chimney, can all cause water to show up in strange areas related to the chimney.

So, do these issues sound familiar?

Deteriorated metal or masonry firebox assemblies

• Rusted damper assemblies

• Rusted fireplace accessories and glass doors

• Rotting adjacent wood and ruined wall coverings

• Water-stained walls and ceiling

• Deteriorated central heating system

• Stained chimney exterior

• Decayed exterior mortar

• Cracked or deteriorated flue lining system

• Tilted or collapsed chimney structure

•The chimney stinks or smells. [When water mixes with creosote in a wood-burning chimney system, it can generate a highly disagreeable odor that can permeate a home!]


Let’s address what could be the culprit — flashing. Manyleaks are flashing related.  Why?  Because we see glued on, tarred on junk.

Once we find and explain the flashing problem, its now time to repair or replace it. Proper chimney flashing has two parts:  The step flashing, and the counter flashing.  The best practice is to cut a groove into the chimney at the top of the flashing and tuck and seal the metal into the structure.


Another issue is the cricket. A chimney cricket defers the water around the chimney instead of letting it pool at the rear of the chimney. It is a common building code that chimneys more than 30 inches wide need a cricket; CSIA Certified Chimney Sweeps often find that the cricket isn’t there or find that the cricket is improperly installed. Sometimes there is a cricket on one side when there should be a corner cricket.


Then there’s spalling.

We all see a lot of flaking chimneys in the area. Spalling is due to water absorption into the masonry.  Brick are like sponge.  They soak up all the moisture, when the water freezes it pops the faces of the brick off. The back-and-forth of cold-warm (freeze/thaw) is a big issue in climates such as Indianapolis.

Don’t forget furnace flues, which are often left out of the equation when replacing, inspecting, or removing a heating appliance. They have had moisture condensing in them for years. We all see the higher efficiency furnaces being installed with no liner kit or the “abandoned” or “orphaned” water heater.

Furnace or boiler flue leakage can cause water problems.  This leads to moisture stains on the chimney and in the home.

Yes, efflorescence can be caused by rain water, but on chimneys it is often excessive moisture from flue gasses.

A good solution is to apply professional grade moisture protection to masonry structures.  This will definitely help prolong the life of these structures. Professional grade products allow the structure to breath, but do not allow water to enter.

Unfortunately, waterproofing  will not fix bad or spalled brick.

Now let’s talk about the roof of the chimney, the crown. Most are cracked and are made of mortar. Few have proper bond breaks. Usually, you have 2 options. If the crown seems solid and is just cracked, not falling apart, we can apply a flexible. If it is not solid, falling apart, or laid on plywood or wood shingles, it should be torn off and replaced.

Did you know that this is what a crown should look like?  It should be poured in a form, 4 inches thick, with a bond break and a drip edge — kind of like a soffit on a house.

Some, made of plain steel or galvanized metal are rusting and hard to remove.  Just like our rusting flashing, common chimney caps made from galvanized metal and rust in a matter of years.  This can cause rust stains on the chimney. Caps keep out rain, animals, leaves and debris.  Stainless steel caps won’t rust.

The best chimney caps are large stainless steel multiflue caps that are custom made and completely cover the chimney top.

Moving inside the home. When we look inside a masonry firebox, we should be looking for signs of water entry.

Water streaks, loose brick, or damaged firebrick can all be caused by water entry.

A lot of times the area will smell musty and damp.

This is also a good time to check for more evidence of settlement.  Look for separation between the profile and the firebox. This usually indicates settling of the chimney or hearth.


When you are checking any factory built fireplaces, make sure you take a moment to look for rust on any surface. Also, try looking through the air circulating grills for water stains or rust; you may be surprised at what you find.




Instead of a masonry crown, a prefabricated chimney has a sheet metal top called the “chase cover.”

Many of these covers are field fabricated and perform poorly.  They are prone to water leakage, water pooling and rust.

Water can show up at ceiling lines, in the firebox, and behind the louvers of the prefabricated fireplace.


If customers hear water dripping when it rains it is not uncommon that the storm collar has failed. As with all vents the storm collar needs to be a proper size and sealed to shed water away from the pipe.

Chimney Safety Institute of America addresses all the hazards associated with water and your masonry chimney in the homeowners section of csia.org.

Special thanks to CSIA Certified Chimney Sweep Jeremy Biswell of The Fluesbrothers Chimney Service in Kansas City, Kansas for insights into the issues with water in chimneys. Find Jeremy and 1,500 CSIA certified professionals in your zip code through our free search engine locator.

2 thoughts on “Rain, water, and common chimney issues in #Spring

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s