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Changing Your Fireplace’s Fuel Source Could Cause Damage

Replacing your traditional wood-burning fireplace with gas logs or a gas fireplace insert is tempting. Gas fires turn on and off with the flip of a switch or the press of a button; they’re temperatures are controllable; they’re generally cleaner and more efficient; and you don’t have to worry about the hassle of dealing with firewood. But if you’re looking to switch your wood-burning fireplace to another type of fuel, you do need to consider the damage it could cause to your masonry chimney without taking the proper precautions.

What is spalling?

Simply put, spalling is the crumbling and cracking of bricks or masonry, generally caused by an excess of moisture. Spalling can cause the face of bricks to pop off, and over time, spalling in your chimney can weaken the structure. When you’re chimney’s bricks are failing, it can allow carbon monoxide, heat, and even flames or sparks to find their way out of your chimney and into your home’s structure, putting your home and your family at risk.

How do alternate fireplace fuels cause spalling?

Your fireplace’s masonry was meant to deal with the byproducts of a wood fire, such as soot and creosote. The byproducts of a gas fire, however, are very different. The primary output of a natural gas fire is water vapor, which condenses on the sides of the chimney as the smoke from the fire cools near the chimney’s top. That water vapor is primarily acidic, containing the same acids found in rain. Because fires rely on oxygen from within a home to burn, the water vapor from a gas fire also often contains the chlorides from cleaning products that present are present in most homes’ air. The acid, chlorides, and moisture wear down a masonry chimney, leading to spalling and a failing chimney.

How do you avoid spalling when switching fireplace fuel sources?

The best way to prevent a problem with your chimney when switching fuel sources is to have your fireplace insert or gas logs installed by a CSIA-certified chimney sweep. That sweep will inspect your chimney to make sure it is compatible with the insert or logs you wish to install. To create the right draft for your new fireplace, which ensures that your fire will combust efficiently, your chimney sweep will make sure that the flue is the proper size for the fireplace. Your sweep also will check to make sure the chimney’s material is well-suited to the fireplace. If your chimney is not ideal for your new fireplace, your chimney sweep can install a flue liner that is the right size and material for your fireplace.

If a new fireplace already has been installed and you are unsure of how your chimney is fairing, your certified chimney sweep will check for damage during your annual chimney sweep and inspection, which is vital even if you are no longer burning wood. Your chimney sweep will be able to identify spalling before it becomes a major issue and recommend a way to address the spalling.

Whether you’re looking to install a new fireplace, or if you’re concerned about your chimney’s compatibility with your new fireplace, call the certified chimney sweeps at Mountain Man Fireplace and Chimney. Our experts will ensure your chimney won’t fall victim to spalling with your new fuel source.

By Jake Johnson on November 30th, 2015 | Tagged with: Tags: , | Leave a Comment

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


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 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