Stories From the Field

Stories From the Field

Post: Residential Chimney Project in Glencoe

Tuesday June 2, 2015

Shortly after moving in, the new owner of this 1950's-era ranch observed heavy efflorescence on the exposed brick chimney shaft in his living room and on the adjacent ceiling. A new roof had just been installed by a reputable contractor (Warner Nelson at Star Roofing & Siding) so we knew the roof was not the culprit.

The new owner had been told that the rebuilt chimney was about a decade old (that's considered a young chimney by our standards), so we popped up onto the roof to have a better look. A close-up inspection revealed a concrete chimney cap cracked in multiple places and very poor mortar adhesion between the bricks (this can happen when ambient temperatures during construction are too high so the mortar dries too rapidly, when the mortar freezes before it has completely cured, or when the mortar has not been mixed correctly). After we removed the roof flashing at the base of the chimney, we were surprised at the extent of the brick erosion and failed mortar.

A concrete chimney cap cracked in multiple places and very poor mortar adhesion between the bricks, with extensive brick erosion and failed mortar at the base of the chimney.

As we dismantled the chimney we were disappointed to see how the previous mason had elected to rebuild the structure. It was a mess. The mortar contained much too much Portland cement, making the mortar too hard for the bricks and virtually guaranteeing the chimney's early demise; improperly sized flue tiles had been used creating a drafting issue (and, potentially, a carbon monoxide issue); and cinder blocks had been used indiscriminately. (We are not fans of cinder block construction.)

The dismantled chimney showing many problems, including mortar made with too much Portland cement, improperly sized flue tiles, and indiscriminate use of cinder blocks.

After dismantling the defective chimney down to the roof deck, we set about rebuilding the chimney the correct way:

  • We used Belden bricks (some of the best clay pits in America are located in Belden, Ohio). These Belden Colony Red Range bricks are more than double the cost of similar looking bricks but will last for generations…the way all bricks should perform. An added benefit was the spot-on color match with the brick facade which the new owner appreciated.
  • We used only Type N mortar, which provided the right balance between strength and softness so that the bricks will not spall or crack apart prematurely.
  • We worked within the right temperature range so that the mortar cured slowly and appropriately and bonded well to the bricks. (We wetted the bricks as we worked just to be sure.)
  • We saved the owner the cost of replacing the metal rain caps because they were in structurally sound condition and could be re-used.
  • We cleaned up the job site and removed all traces of debris so that the roofer could return to permanently re-flash the base of the chimney using modified roof flashing and galvanized counter-flashing.

Our correctly built chimney, with Belden bricks, type N mortar, and re-used rain caps, cleaned up and ready for the roofer to return to re-flash the base.

Whether your project is a residential chimney or a mile of parapet wall rebuild, we treat every job with respect and care. Exactly what you should expect from a masonry restoration company in continuous operation for over 60 years.

Thank you for the opportunity to be of service!


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