Our Company Blog

3 Ways Water Ruins Your Chimney

 

We might start sounding like a broken record after a while, but the truth is the truth: Moisture is your chimney system’s worst enemy. Sure, we have to consider other potential chimney problems in providing proper chimney care, like fire hazards and proper draft. But when Mountain Man Fireplace and Chimney technicians are called out for chimney repairs, more often than not, the culprit behind that repair need is water.

How Water Damages Your Chimney

One potential result of excess water in your chimney is damage to your mortar joints.

One potential result of excess water in your chimney is damage to your mortar joints.

Here’s the thing about the various sources of chimney trouble: Most of them are either irregular, or relatively avoidable. Yes, a lightning strike could cause serious damage to your chimney, but those don’t happen frequently. Same goes for seismic events. And while a chimney fire is a serious concern, we can do a lot to make those far less probable, from sweeping your chimney every year to guiding you toward proper burning practices (like always and only burning seasoned or kiln-dried firewood).

Water, on the other hand, is consistent. Season after season, year after year, rain, snow, sleet and other forms of precipitation bear down on your chimney exterior, wearing at the masonry and the various components of your system. You can’t keep your chimney clear of moisture, but you can know how moisture attacks and damages your chimney, and learn what you can do to protect the system and avoid extensive damage.

3 Types Of Water Damage

Rust/Corrosion

Many components of your chimney system are made out of metal, including your chimney flashing and chimney cap. In pre-fabricated chimney systems, you’ll have a metal chimney chase installed at the top performing a job similar to that of a masonry chimney crown: diverting water away from the flue opening. Depending on what those components are made of, rust and corrosion could be a concern. Galvanized metal is a budget-friendly material, but it doesn’t stand up to the elements nearly as well as copper or stainless steel. Galvanized caps and covers can start to fail even in just a few years. Rust and corrosion are things we’ll look for during your chimney inspection, but if you see rust streaks on your chase cover or chimney cap or notice damage on your flashing in between inspections, call Mountain Man — those components likely need replacing.

Spalling

Spalling masonry is masonry that’s flaking, chipping or crumbling, and that can span from surface flaking on your chimney crown to bricks that look like their faces have popped clean off. And yes, water is your culprit here too. Water causes spalling often through the freeze/thaw cycle — moisture weaves its way into small imperfections like cracks, then the water freezes as the temperatures drop, and expanding ice breaks open the masonry from the inside. But the regular assault of rain and snow can just slowly wear at your masonry too, causing the surface to flake and crumble.

Mortar Joint Damage

Bricks will generally stay stronger longer than the mortar joints holding them together. So after years of being bombarded by precipitation, it’s common for mortar joints to recede or crack, allowing moisture to move toward the interior of your chimney, affecting other components (like rusting your throat damper or wearing down the mortar joints in your firebox). Leaks like these can also create a mold issue. Mold feeds on moisture, and if it starts growing in your chimney, it can contribute to health problems, from skin irritation to respiratory problems, for the people in your home

How To Keep Water From Ruining Your Chimney

Your chimney system was designed with components that protect it against water. Your chimney crown or chase cover usher rain away from the flue; flashing keeps water from intruding where your chimney meets the roofline; a chimney cap helps protect the flue opening from letting precipitation in. When Mountain Man technicians perform your annual chimney inspection, we check all of those components to ensure that they’re performing properly and effectively — and if they’re not, we can do the right repairs to change that. So keeping up with those inspection appointments: a big step toward keeping water from ruining your chimney.

Another proactive step we can recommend is having Mountain Man techs apply a waterproofing sealant to your masonry. Waterproofing keeps excess moisture from being absorbed, and protects the masonry itself, helping to extend its service life. It’s a really worthwhile extra step that helps you avoid damage and leaks, and care for a beautiful part of your home.

If you have any questions about moisture damage to your chimney — or if you’d like to make an appointment with Mountain Man Fireplace & Chimney’s CSIA-certified technicians — just give us a cal

Why is My Chimney Leaking?

There are few things more aggravating to a homeowner than having water leaking into their home. Finding the exact source of a leak around a chimney can be particularly frustrating.  The inherent complexity of having a masonry structure pass through a framed roof can turn the proper diagnosis of a leaking chimney into a time-consuming headache.

Annual chimney maintenance is helpful because it alerts you to problems early, before they become catastrophic.

Annual chimney maintenance is helpful because it alerts you to problems early, before they become catastrophic.

To understand the fundamentals of why a masonry chimney will or won’t leak, let’s start at the top of the flue and work down to the roofline.  First, if you don’t have a chimney cap, get one.  An uncovered chimney allows whatever rain and snow are falling to enter right into the fireplace flue.  Over time, that water erodes the mortar joints between the flue tiles and it also damages the chimney as the water is heated into steam during operation of the fireplace.

The chimney crown is the ‘lid’ over your chimney.  It’s useful to think of a chimney as a hollow box built out of cinder blocks or bricks.  To keep water from entering the chimney from above, a crown is poured.  The crown should be concrete that is 4” – 5” thick and contoured to drain moisture.  Lots of chimney crowns in our area were just built with mortar instead of concrete or they lack an expansion joint to allow the top flue tile to expand when the fireplace is in use.  The result is cracks and erosion that allow water to penetrate and cause increasingly larger cracks as the freeze-thaw cycle occurs.

The sides of a masonry chimney are often the least understood culprit when making a leaky chimney diagnosis.  Like all masonry materials, mortar joints will allow water penetration when saturated.  When the mortar joints are cracked or damaged, water easily flows through them and into the space between the cinder block structure and the stone veneer.  It flows downward until it reaches the framing of the roof and into your home.  Even in our dry climate, when a chimney is exposed to excessive rain and snow, it will absorb moisture through the rocks or bricks on the sides. The solution is to locate the weakened joints and cracked rocks and seal or replace them as necessary.

Where the chimney meets the roofline can be the most complicated region of a leaking chimney to diagnose.  Every roof-chimney interface should have an overlapping system that includes both flashing and counter-flashing.  The flashing starts under the roofing materials and runs up alongside the chimney.  The counter-flashing starts out with a ‘cut’ into the side of the chimney and then overlaps the flashing to create a barrier to water intrusion.  Unfortunately, a huge percentage of homes in our community have chimneys that are flashed improperly.  We often see chimneys where the counter-flashing is just placed along the chimney and ‘sealed’ with some type of goop.  WRONG!  Chimneys like these need significant repairs to keep the water out of your home.

To correctly diagnose and fix a leaking chimney, we evaluate the entire chimney as a system: top (cap and crown), middle (stonework or bricks) and bottom (flashing and counter-flashing).  If any of the three sections is leaking, then the chimney has a potential for water to enter the home.  Next month we’ll explain how to find the leaks on a framed chase with a factory-built chimney.

To schedule a fireplace/chimney sweeping and/or inspection – call us today at Mountain Man Fireplace and Chimney, Inc – (303) 679.1601 / 838.3882 or electronically at office@MtnManChimney.com.  Semper Fi!