Solid Rock Masonry

09/04/2026

Heating season is close enough to start thinking about it.

If you own a masonry heater, there is one job that matters more than any other before the first real fire, and most owners have never done it. You have to vacuum the fly ash out of the heat exchange channels.

A masonry heater does not vent straight up. The hot gas leaving the firebox travels a long path through channels and chambers, giving up its heat to the masonry along the way. That is why the exhaust leaves at 200 to 300 degrees instead of the 600 to 900 a wood stove sends up the flue. It is also why fine grey ash settles out at every turn and every horizontal run.

One season lays down a measurable layer. Several years of skipping it will choke the channels down until the heater will not draft at all.

The photos here are what is behind your cleanout doors. The round openings in the first are the cleanouts themselves. The second is standard bottom channeling in firebrick, and every horizontal surface you see there collects ash. The third is what a bench channel should look like after it has been vacuumed: clear floor the whole way through.

One thing to watch for while you are in there. You should never find shiny black creosote inside a masonry heater. Grey fly ash and dull black soot are normal. Shiny creosote means the wood was wet or the damper was being closed too early, and both are worth fixing before you burn another season on it.

We just put the full routine on the site: the step by step vacuuming procedure, how often the chimney needs cleaning, what to check on the grate and gaskets, and a maintenance schedule you can print and stick inside a cabinet door.

https://solidrockmasonry.com/masonry-heater-maintenance/

Eric Moshier, Certified Heater Mason
Solid Rock Masonry, Duluth MNhttps://solidrockmasonry.com/masonry-heater-maintenance/

Masonry heater maintenance done right: vacuum the heat exchange channels through the cleanouts, clean the chimney, and check the heater every fall

09/01/2026

I've been building masonry heaters for about 25 years, and I've spent a lot of that time around the rocket world too. I've been lucky enough to spend time with some of the people who built this field, Erica Wisner on the Builder's Guide, Lasse Holmes, and Peter van den Berg over at Wild Acres. There's good work being done here.

One question keeps coming up when people call me: can I get one permitted? I put together a page that lays out what I know. Where rocket mass heaters came from, what they're like to live with, the difference a batch box makes, and why cob construction runs into trouble with building officials and insurers. It's a paperwork problem more than a design problem. I also included what I build for folks who need something that will pass inspection.

Everything on the page is sourced so you can check it yourself. Happy to answer questions.

Rocket mass heaters and the code. Why cob builds cannot be permitted, what can, and the SR-13HCH and SR-18HCH from $7,016. Duluth, MN. 218-343-2978.

08/12/2026

One fire. One chimney. Two rooms. And a set of signed Salvador Dali tiles built right into the wall.

This is a two-sided Kachelofen we built in Dubois, Wyoming, set into the wall between two rooms so it shows a finished face and a working firebox on both sides. One face is white with a blue crown, blue mantle, and a heated blue tile bench. The other is deep green with hand-painted accents. Every tile was thrown, glazed, and fired by hand by our potter Sharon to the exact RAL colors the clients picked. The Dali tiles were a wedding gift, and rather than let them sit in a box, we designed the whole white face around them so they get seen every day.

A Kachelofen is a tile stove, the way homes in Germany and Austria have been heated for six hundred years. You burn one short, hot fire for two to three hours. The masonry stores that heat and radiates it back gently for the next 12 to 24 hours. No fan, no blower, no cold end of the room. The surface stays warm to the touch instead of scorching, which is exactly why the heated bench built into this one is the most fought-over seat in the house.

This heater carries a 2,000 square foot home through Wyoming mountain winters on one armload of wood a day.

We design and build custom Kachelofen, Swedish kakelugn, and masonry heaters across the country from Duluth. See the full start-to-finish build here: https://solidrockmasonry.com/custom-kachelofen-tile-stoves-built-in-the-usa/

Send us your room, your climate, and the colors you're drawn to, and we'll start the drawing. Call 218-343-2978.

Authentic German and Austrian Kachelofen tile stoves, custom built across the USA. See a two-sided Kachelofen built start to finish.

08/05/2026

Do Masonry Heaters Need Outside Combustion Air?
https://solidrockmasonry.com/do-masonry-heaters-need-outside-combustion-air/

Short answer: in most homes, no. And a direct outside air duct connected straight to the firebox can actually cause the problem it's meant to solve.

A masonry heater is not a wood stove. It burns a short, hot batch fire for two to three hours, then sits with the damper closed and draws no house air for the other 21 or 22 hours of the day. During the burn it pulls a modest amount of air, under about 30 liters per second, and CMHC-funded research back in 1994 showed that keeps even a tight house well within the safe pressure limit. The heavy masonry mass also holds strong chimney draft long after the fire is out, which removes the draft-reversal risk that makes outside air necessary on low-mass appliances.

Here's the part that surprises people: a sealed duct piped straight to the firebox can reverse in normal wind and carry hot combustion gases, possibly carbon monoxide, back out through ducting never rated for heat. For genuinely ultra-tight homes, the better answer is running the home's HRV or ERV in boost mode during the burn. Some local codes still require an outside air pipe, so always confirm with your local building official, and install a CO detector regardless.

Questions about your specific home or project? Call 218-343-2978.

Do masonry heaters need outside combustion air? In most tight homes, no. A Certified Heater Mason explains the research, the hazards, and safe solutions.

08/04/2026

Every tile on this stove was made by hand, one at a time, and the only signature on the whole thing is hidden where nobody will ever see it.

Back in 2022 we built a round, white-glazed Swedish tile stove, a kakelugn, in Stockholm, Wisconsin. The clients came to us with a photo of an antique and a curved alcove already tiled sage green. They didn't want the antique. They wanted that form, in their house. On a round stove you can't cut your way out of a mistake, so every curved tile had to be made to fit the heater from the start. Sharon Moen of Falconfire Pottery in Duluth formed, glazed, and fired every single one by hand.

Inside, it's a Russian bell rather than the traditional Swedish five-run channel. Same physics, fewer parts, and far easier to clean and harder to build wrong. Hot gas rises around the flue liner, gives its heat up to the masonry, then falls and finally exits up the chimney. By the time it leaves, most of the energy from the wood is in the stove, not the sky. That's why it burns a fast fire for 2 to 3 hours and radiates heat back into the room for the next 12 to 24.

When we rebuild antique kakelugns, we routinely find the potter's stamp pressed into the back of a two-hundred-year-old tile. Sharon's mark is on the back of these. In two hundred years, somebody is going to take this stove apart and find it.

We built the whole thing in order, from the first sketch to the brass doors, and photographed every step: https://solidrockmasonry.com/2026/07/schabel-swedish-tile-stove-build/

Site-built masonry heaters run $30,000 to $40,000. We build them nationwide from Duluth. Call 218-343-2978.

Want a reminder set for this one too, on the next open weekday slot? That would put it Tuesday, August 4 at 9 a.m., since next week's Tue through Thu are already taken.

A round Swedish tile stove (kakelugn) built by Solid Rock Masonry with Handmade tile by Falconfire Pottery with a Russian bell heater core.

08/03/2026

Trout Unlimited and Coldwater Conservation
https://solidrockmasonry.com/2026/07/trout-unlimited/

Solid Rock Masonry is a proud supporter of Trout Unlimited, the nation's leading coldwater conservation organization. When I'm not building masonry heaters, I'm usually standing in moving water somewhere, chasing trout or fly fishing the salt, so clean, cold water is not an abstraction around here. It's a core value of the business.

Trout Unlimited was started in 1959 by a handful of Michigan anglers and has grown to more than 300,000 members and over 400 chapters. Right here in the Duluth area, the Gitche Gumee chapter is part of a Minnesota effort that has restored well over 100 miles of trout streams, including barrier removals on Tischer Creek and the Baptism, Manitou, and Two Island Rivers that reopened about 16 miles of colder, healthier water.

There's a real connection to what we build, too. A masonry heater burns a hot, complete fire and puts out very low particulate emissions compared to an ordinary wood stove. Cleaner air and cleaner water go hand in hand. If you fish the water around Duluth and the North Shore, the Gitche Gumee chapter is a great place to get involved. 218-343-2978.

Solid Rock Masonry supports Trout Unlimited. Learn what TU does to protect coldwater trout streams and why clean water is core to our life

07/31/2026

The History of the Kakelugn
https://solidrockmasonry.com/kakelugn-history/

The kakelugn, the Swedish tiled masonry heater, is one of the most efficient wood-burning heaters ever built, and the design is over 250 years old. In 1767, facing a real firewood shortage, the architect Carl Johan Cronstedt and the statesman Fabian Wrede redesigned the tile stove around a system of tall, switchback smoke channels, published under the motto "for the saving of wood." Instead of letting the heat rush up the chimney, the gases wind roughly ten meters through the masonry, giving up nearly all their heat before they ever reach the flue.

That short, fierce fire warms the stove instead of the sky. You fire it for two to three hours, close it down, and the glazed tile radiates gentle heat for the next 12 to 24. The golden age of these stoves produced showpieces from the Marieberg and Rorstrand factories, and one of the finest collections outside Sweden is right here in Minnesota: eleven antique kakelugns at the American Swedish Institute in Minneapolis.

We build and restore tile stove heaters in this same tradition, on the same 1767 principle, engineered into our SR Core system today. 218-343-2978.

Kakelugn history: how Sweden invented the tiled masonry heater in 1767 to survive a wood shortage, how it works, and why it still matters. From Solid Rock Masonry.

07/31/2026

Nielsen Stone Masonry Heater
https://solidrockmasonry.com/2026/07/nielsen-stone-masonry-heater/

Here's an updated photo of the Nielsen SR-22 stone masonry heater, a J-loop design we built with fellow heater builder Derek Kowalchuck of Fiddle Rock Masonry. It has a black, directly fired bake oven and a three-sided heated bench, all finished in local granite fieldstone that the Nielsen family hand-picked right off their own farm, along with a granite hearth, capping slabs, and a side wood box.

Under the stone it's a Hybrid Core, built mostly from firebrick with a few cast refractory pieces and large clay tile liners forming the bell channels. The firebox has a replaceable inner liner, so if it ever wears out down the road the core doesn't have to come apart to fix it. The whole mass is wrapped in a fiberglass expansion joint before the stone goes on, which is what keeps a heater like this from cracking as it heats and cools.

Fire it hard for two to three hours and the masonry radiates gentle heat back into the house for the next 12 to 24. Want one like it? Call 218-343-2978

07/30/2026

Your chimney isn't failing because of bad brick or bad stone. It's failing because of water, and almost always because the crown on top was never built right in the first place.

On most chimneys we open up, what's on top isn't a crown at all. It's a wash, mortar troweled over the brick and sloped a little. Mortar is not a roofing material. It cracks, and once it cracks the chimney becomes a funnel, pouring water down the inside of the masonry and breaking it apart from the top down. You see the damage near the top and think you have a mortar problem. You have a crown problem.

The way we build a crown is a cast concrete crown with a real overhang and drip edge, and then a formed metal crown over the top of it. The concrete does the structural work, the metal takes all the weather, and the concrete never sees a freeze-thaw cycle again. That's the whole philosophy of this company in one detail: don't build a crown and hope, build a crown and then make sure it's never exposed to the thing that kills crowns.

The other chimney-killer is the wrong mortar. Old stone was laid in soft lime mortar for a reason. Point it with hard modern Portland cement and you invert the whole system, the mortar becomes the strongest thing in the wall, and the face of the stone pops off instead of the joint. That's spalling, and a spalled stone can't be repaired. Most contractors use whatever is in the bag on the truck. That's how a hundred-year-old chimney gets destroyed by the people hired to save it.

We don't patch chimneys. We find out why yours failed, fix that, and repair the damage properly, so it lasts thirty years instead of five.

Losing mortar, dropping pieces, staining, or smoking? Let us look at it before someone caulks it. See the before-and-after work here: https://solidrockmasonry.com/stone-chimney-fireplace-restoration/

Call 218-343-2978.

Stone chimney restoration and fireplace repair in Duluth, MN by a third-generation mason. We find why the masonry failed in a freeze-thaw climate and fix the cause.

07/29/2026

Seven months. That's how long we spent on a custom stone home above a northern Minnesota lake, and most of that time went into selecting and cutting stone, not laying it.

Granite ashlar ledgestone wraps the exterior in a drystack joint, which means the joints are raked back so tight and clean that from a few feet away the wall looks like the stones simply stack on each other with nothing between them. The mortar is there. You just can't see it. Limestone runs through the interior, and over the spirits room we hand-laid a brick groin vault, two barrel vaults crossing at right angles, built over temporary formwork and holding itself up on nothing but compression once the forms come out. That's medieval technology, and almost nobody builds one anymore.

Whether it's one feature wall or a full stone home, the thing that makes stone last up here isn't the stone you pick. It's whether the wall is built to handle freeze-thaw. Water gets behind every cladding. A wall with a real drainage plane, proper flashing, and open weeps sheds that water and dries out. A wall without it traps the water, freezes, and pushes the stone off. That second wall is the one people call us to rebuild.

We build in full-bed stone and thin stone veneer, and we'll tell you honestly which one fits your house, your structure, and your budget.

See the lake home and more of our stonework: https://solidrockmasonry.com/custom-stone-homes/

Thinking about a stone project? Call 218-343-2978.

Solid Rock Masonry builds custom stone homes in Duluth and northern Minnesota & Wisconsin. 25+ years experience and over 800+ projects