Granite Fireplace on Island Lake

This Corinthian granite fireplace sits in a home on Island Lake, north of Duluth, Minnesota. Solid Rock Masonry LLC built it around a hand-built 36 x 36 inch PriorFire Rosin firebox, 18 inches deep. In addition, a massive granite hearth anchors the whole fireplace. Our owner, Eric Moshier, is a third-generation mason and Certified Heater Mason with 40+ years in the trade. We build custom stone fireplaces across Duluth, the North Shore, the Iron Range and northwest Wisconsin.

By Eric Moshier - Certified Heater Mason, Third-Generation Mason, MHA Technical Committee Member, ASTM E1602 Masonry Heater Group Member

Corinthian granite fireplace in a home on Island Lake north of Duluth, MN — The finished granite fireplace on Island Lake.

Why does this granite fireplace use a Rosin firebox?

A Rosin firebox has a curved back and a shaped throat. As a result, the smoke rolls smoothly up into the chimney instead of tumbling. That lets the fireplace draw well on a far smaller flue than a Rumford or a standard fireplace with the same opening. This one runs on an 8-inch Class A chimney.

A smaller flue also pulls less warm room air up the chimney. That is where much of the Rosin’s efficiency comes from. However, the PriorFire design is not ours. It is the work of Chris Prior of Adirondack Chimney Company, and we build it by hand on every Rosin fireplace we do. Our custom stone fireplaces page explains the flue math in more detail.

Hand drawing of the Rosin firebox layout for the Island Lake granite fireplace — First, the firebox layout on paper.

How do we build a curved Rosin firebox?

We cut, grind and shape each firebrick over a curved form. Then we lay the curved back course by course, so the curve stays true from the hearth to the throat. The firebox is the working heart of any granite fireplace.

Firebrick cut and set against a curved form for a Rosin firebox back — Next, firebrick goes up against the curved form.

Curved firebrick courses for a Rosin fireplace firebox — The curve takes shape one course at a time.

Curved Rosin firebox back rising on its form — Then the curved back rises on its form.

Rosin firebox walls and curved back laid in firebrick — After that, the side walls join the curved back.

Back of a hand-built Rosin firebox showing the curved firebrick — The outside of the curved back.

What goes behind the firebox?

Next, we wrap insulation behind the firebox and smoke chamber before the block and stone go up. That keeps heat in the firebox, where it belongs, instead of soaking into the back of the granite fireplace.

Insulation wrapped behind a Rosin firebox — Insulation going in behind the firebox.

Insulated space between the Rosin firebox and the fireplace backing — The insulated space behind the firebox.

Insulated smoke chamber above a Rosin firebox with block backing — Similarly, the smoke chamber gets wrapped too.

Rosin firebox with steel lintel set inside the block fireplace shell — Then the steel lintel goes over the firebox opening.

Inside view of the curved back of a Rosin firebox — Inside the finished firebox, looking at the curved back.

What chimney does this fireplace use?

This granite fireplace vents through an 8-inch Class A chimney. In short, the Rosin firebox let us use a much smaller flue than a traditional fireplace of the same size would need.

Class A chimney anchor plate set on top of a Rosin fireplace smoke chamber — The Class A chimney connection on top of the smoke chamber.

Class A chimney rising through the ceiling above a granite fireplace — Afterward, the Class A chimney runs up through the ceiling.

How was the granite fireplace face laid?

We laid the face in New York Corinthian granite in an ashlar pattern, with standard gray Type S mortar. In addition, we built a granite arch over the firebox opening. Finally, the hearth is one massive slab of the same granite. We rolled it into place before the walls of the house went up.

Corinthian granite ashlar stonework going up on a fireplace — Granite ashlar going up beside the firebox.

Corinthian granite corner on an ashlar stone fireplace — A granite corner, laid in ashlar.

Granite arch and massive granite hearth on a Rosin fireplace — Next, the granite arch and the massive hearth.

Close-up of a granite stone arch over a Rosin firebox — Close-up of the granite arch.

Top of the Rosin firebox opening under the granite arch — The top of the firebox opening.

Corinthian granite fireplace corner and chimney breast — Granite on the chimney breast corner.

Finished Corinthian granite fireplace with arched firebox opening and granite hearth — Afterward, the finished granite fireplace.

Inside a finished PriorFire Rosin firebox with a curved firebrick back — Inside the finished Rosin firebox.

Curved firebrick back of a finished Rosin firebox — Finally, the curved back, ready for its first fire.

Can you build a granite fireplace near Duluth?

Yes. We work within about 1.5 hours of Duluth, including Island Lake, the North Shore and the Iron Range. For more of our work, see the project gallery. Also, two more Rosin fireplaces we built are the Luhrsen Lake Superior stone fireplace and the Anderson fireplace.

However, if you want real heat from wood, look at a masonry heater instead. For an older fireplace that needs work, see our stone chimney and fireplace restoration page. To start a project, use our contact page. Jim Buckley’s rumford.com is a good place to read about Rumford fireplaces.

Frequently asked questions

Where is this granite fireplace?

It is in a home on Island Lake, north of Duluth, Minnesota.

What stone is on the fireplace?

The face is New York Corinthian granite laid in an ashlar pattern with standard gray Type S mortar. The hearth is one massive slab of the same granite.

What size is the firebox?

It is a 36 x 36 inch PriorFire Rosin firebox, 18 inches deep, built by hand in firebrick.

What chimney does it use?

It vents through an 8-inch Class A chimney.

Do you build fireplaces around Duluth and up the North Shore?

Yes. We build stone fireplaces within about 1.5 hours of Duluth, including Island Lake and the North Shore. Call 218-343-2978 for an estimate.

Corinthian Granite Fireplace on Island Lake with a 36-Inch Rosin Firebox