Chimney repair with a free inspection in Thornton Park

A coating is not a new crown

BIA guidance on coatings for brick is blunt about what a clear repellent or a brush-on coating can do. Water usually gets into masonry at cracks and separations, and a repellent cannot stop water getting in through ineffective caps or copings or through mortar joints that were never filled.

A coat spread over a broken crown also hides it. The cracks stop showing from the ground while water keeps finding them. The same guidance says a repellent is not recommended in place of common repairs such as repointing or replacing spalled and cracked brick.

When a crown is cracked, broken or has lost its slope, the estimate prices a crown repair or a new crown, not a coating. Any water repellent on the masonry below is a separate question for after the repairs, written as an optional line rather than as the fix for the top.

The mortar used to repoint matters

Stronger mortar is not necessarily better mortar. BIA guidance on mortar says no single mortar is best for all purposes and advises choosing the lowest compressive strength that meets the needs of the job. For repointing, it names compatibility between the existing brick and mortar as the most important consideration.

Mortars laid before the early twentieth century were mostly lime and have lower strength, so older brickwork likely needs a weaker repointing mortar than new construction would use. BIA maintenance guidance wants repointing mortar no stronger than the original, and it cautions that a mismatched mortar can make the old brick spall and crack.

The reason is stress. A repointing mortar stronger than the original concentrates stress where brick meets mortar, and the brick faces can spall. The mortar is chosen for the chimney in front of us, and its type is named on the estimate.

Options for relining a masonry flue

When a flue needs a new lining, the Florida Building Code keeps the choice to a short list of materials for ordinary residential appliances. The choice starts with the appliance, because the lining has to suit whatever is connected to it.

The size and shape of the existing flue, any bends in it and how much sound masonry remains narrow the choice further. Listed materials are installed per their listings and the maker's instructions, so the product chosen also fixes how the job is done.

Our chimney liner installation service lays out which of the options below fit your chimney. Each one is priced on the estimate so the decision stays yours.

• Clay flue lining, rebuilt inside the chimney
• A listed and labeled chimney lining system
• A factory-built chimney unit listed for use inside masonry
• Another approved material that resists the heat and condensate

A chimney that vents a furnace or water heater

Some masonry chimneys carry more than a fireplace. A furnace, boiler or water heater may vent into its own flue in the same chimney, through a connector that enters from the side in a utility room, closet or garage.

A masonry chimney's lining has to suit the appliance connected to it, and the Florida Building Code sends flue linings for gas appliances to its fuel gas chapter. It also says the space around a lining system installed inside a masonry chimney may not be used to vent any other appliance. A flue built for a fireplace is not automatically right for a water heater, and the reverse holds too.

The appliance itself belongs to the trade that services it. Our crew in Thornton Park handles the chimney side, meaning the flue, its lining, the inlet at the masonry and the top, and the estimate says plainly which items are ours and which belong to that trade.