White Stains On My Chimney? What Is Efflorescence?

A common issue with masonry chimneys is the formation and eventual build up of a white substance called efflorescence. While many people may assume the residue is a normal occurrence in an aging chimney, it can actually be a sign of underlying issues.

So What Exactly Is Efflorescence?

Efflorescence indicates the presence of water in your chimney. The bricks in a masonry chimney contain minerals such as sodium, potassium, calcium, and magnesium. When water seeps into the porous masonry materials a white stain develops as the water evaporates and brings the minerals to the surface. Over time this substance can accumulate and may have a crystallized or “fuzzy” appearance.

Why Efflorescence Is More Than Just An Eye Sore.

While the white stains on your chimney might not be the most appealing to the eye, these marks are also a tell tale sign that water has access to your chimney. Efflorescence occurs when underlying issues allow water to enter the brick such as, cracks, a damaged liner, no cap, or deterioration of the mortar. While your chimney may not need immediate attention, if left untreated water exposure can lead to structural damage. Efflorescence isn’t restricted to just the outside of your chimney and can occur on the inside of your home as well. Improper flashing (the seal between the roofing material and the chimney) can leave room for water to leak directly into your home. Water inside your home will not only damage your chimney but reek havoc on your ceilings, floors, and create the perfect environment for mold growth. The best time to service your chimney is BEFORE a problem occurs. preventative maintenance can help keep you and your family safe but also save your wallet!

What Can I Do About Efflorescence? 

While you may not be able to completely block the formation of efflorescence, there are preventative measures that you can take to reduce the effects of water damage. Here at Don’s we offer crown repair, waterproofing, flash seals, chimney caps, liners and more to keep your chimney in tip top shape. If you have efflorescence or believe your chimney needs service give us a call today to schedule an inspection!


Example of a cracked and water damaged chimney vs. a chimney with preventative measures such as a chimney cap and proper flashing.



TO PREVENT CHIMNEY FIRES – Creosote is a highly flammable substance that naturally forms during the combustion process while burning wood. The more creosote that accumulates in your chimney the higher the risk of a chimney’s fire.

TO PREVENT CARBON MONOXIDE POISONING – Cracks or gaps in your firebox or flue are the points of entry for dangerous deadly gases like carbon monoxide to enter into your living area.

Whether you heat your home with wood, coal, gas or oil, over time each of these fuels can create combinations of condensation, acidic build-up or creosote. These naturally forming by-products of combustion can and will, over time, deteriorate the clay flue tiles and mortar inside your chimneys and, if left unattended, can lead to the unthinkable – deadly carbon monoxide gases escaping into the home or chimney fires.

Our certified technicians are trained to identify and remedy any issues that arise from the deterioration of the inner chimney flue and the exterior. We know that protecting your family and home is your # 1 priority so call us today to schedule your chimney sweep and inspection.




…….and May flowers which the rain is great for along with our gardens and wells but not so much for masonry chimneys –  especially ones that have suffered damage from the cold New England weather.  Signs of leaky chimneys can be water in your firebox, a rusty fireplace damper, water in your basement, staining on your ceiling as well as damaged wallpaper surrounding the chimney area.


If the chimney does not have a cap it is possible that the rain is falling straight down the chimney, the crown (the cement part on top of the chimney) is cracked and rain/snow is falling down in, the chimney is leaking from the inside out (which would be why wallpaper is damaged) due to condensation from burning a gas appliance (which means the chimney probably isn’t lined).  The flashing ( material used to keep water from entering into the area where the chimney protrudes through the roof line) needs to be repaired/replaced or the leaks are coming through the brick due to their porous construction.

Sometimes, a leak starts in a different place such as your roof but finds its way to the chimney, and then visibly enters the inside of a room at the point of the chimney which can make it tricky to assess where the actual leak is coming from especially if the chimney has no obvious signs of being compromised.


Chimneys are built from porous materials (brick & mortar) – over the course of the winter, your chimney absorbs the melting snow/rain and when it goes below 32 degrees, as we all know, freezing takes place.  Chimney damage occurs when we start to thaw out.  The brick and mortar expand creating cracks and or spalling (faces of the brick fall off) which in turn means a point of entry for water and leaking to occur.


We offer services such as cap installation, flashing repair, crown repair to fix the cracks on top or crown reconstruction (depending on the damage) as well as a professional waterproofing treatment which will halt the water from penetrating through the bricks and mortar all while still allowing the chimney to breathe (allowing any moisture/vapors on the inside to escape). Sealants should never be used since these products will lead to more damage.  Our waterproofing treatment has a warranty of 12 years.

Chimney maintenance is our specialty so give us a call or email info@donsstoveshop.com  today to discuss our recommendations for your leaky chimney.