--- title: "Clearances and the hearth under a pizza oven: walls, roofs and the insulated floor" description: "Why each maker publishes its own distances, what counts as outdoors under a patio roof, the stand and insulation beneath a dome, the counter under a gas oven…" url: "https://pizzaovenrepair.center/guides/clearances-and-the-hearth-under-an-oven/" date_modified: "2026-09-26" --- Installation and setup # Clearances and the hearth under a pizza oven: walls, roofs and the insulated floor Pizza oven clearances come from each maker's installation manual and differ widely: Kalamazoo asks 6 inches at the sides and back of its gas oven, Chicago Brick Oven 10 inches around its dome and 36 inches in front of the door, Coyote 36 inches to combustibles. The stand must be noncombustible, with insulation under the hearth even on concrete. By [PizzaOvenRepair.center technical team](https://pizzaovenrepair.center/authors/technical-team/) Published September 26, 2026 ## At a glance. A pizza oven throws heat in every direction at once: out of its mouth, through the dome, up the flue and down into whatever it stands on. The distances to walls and roofs and the layers beneath the floor are set by each maker for that one model, and an installer who works from the manual rather than from habit is the difference between a warm stand and a scorched one. Read the whole guide ### Where the numbers come from The installation manual for that exact model Distances to combustibles run from 1 inch to 36 inches across the makers. ### Overhead Never under combustible construction Alfresco, Kalamazoo and Coyote all say so in plain words. ### The stand Masonry or metal, never wood Chicago Brick Oven's typical base is block legs under a 4-inch reinforced slab. ### Under the floor Insulation boards, even on concrete A noncombustible base does not replace the insulation the maker specifies. In this guide 1. Why each pizza oven carries its own clearances 2. Roofs, pergolas and eaves above the oven 3. The stand and hearth under a wood-fired oven 4. The counter under an outdoor gas pizza oven 5. Floors and walls around a deck oven or conveyor oven 6. Questions ## Why each pizza oven carries its own clearances A countertop gas oven with a steel jacket, a refractory dome wrapped in a blanket and a commercial deck oven lose heat through different surfaces, so their makers test them separately and print different distances. The table below shows how far apart the published figures are. None of them can be borrowed from a neighbor's oven or from a rule of thumb; the installer reads the manual for the model on the order and the local building and fire rules, and the larger number wins. Combustible means anything that can char or burn: wood framing and decking, siding, a pergola, a fence, plastic laminate, even a painted or varnished finish. Noncombustible means stone, brick, concrete, block and steel. Many makers allow smaller gaps to noncombustible walls, but Chicago Brick Oven and Alfa both warn that the required air spaces must never be packed with insulation or anything else. *Published clearances to combustible materials, by maker and model family* | Pizza oven | Sides and back | Above or overhead | In front of the mouth | | --- | --- | --- | --- | | Kalamazoo Artisan Fire (gas, countertop) | 6 in | 12 in above; never under an overhead combustible surface | Counter should extend 9 in past sides and back | | Alfresco countertop gas oven | 12 in behind the rear exhaust; 1 in around the base | Not under unprotected combustible construction | Not stated | | Coyote Duomo (wood-fired) | 36 in | Not under combustibles at any height | 36 in | | Chicago Brick Oven CBO-500/750 (wood-fired) | 10 in | 18 in above the dome; 30 in below | 30 in each side of the door, 36 in in front | | Marra Forni static (commercial) | 2 in | Per the venting method | 30 in beside the door opening, 36 in in front | Source: [Kalamazoo — Artisan Fire Pizza Oven Use and Care Guide (North America)](https://cdn.shopify.com/s/files/1/0957/4006/8119/files/Kalamazoo-Artisan-Fire-Pizza-Oven-Use-and-Care-Guide-North-America-English.pdf) — 6 inches at sides and back, 12 inches above, never under an overhead combustible surface, noncombustible surface extending 9 inches, 36 to 42 inches high, 100-pound oven; definitions of an outdoor installation; [Alfresco — Pizza Oven Care and Use Manual (AXE-PZA)](https://alfrescogrills.com/wp-content/uploads/2021/07/AXE-PZA-CARE-AND-USE-MANUAL-SERIAL-N%C2%B0-18-00000-FORWARD.pdf) — 12 inches from rear exhaust and 1 inch around the base to combustibles; never over, under or next to unprotected combustible construction; never on combustible countertops; built-ins need bottom access and an access door to the shutoff and GFCI; [Coyote — Duomo Wood Fired Pizza Oven Owner's Manual](https://coyoteoutdoor.cdn.prismic.io/coyoteoutdoor/aBI1GfIqRLdaBwbi_Coyote_Wood-Fired_Pizza_Oven_Owners_Manual_2.pdf) — 36 inches to combustibles at sides and rear and 36 inches from the mouth; not under combustible material at any height; nothing within 10 feet of the chimney cap top; wood decks are combustible; [Chicago Brick Oven — CBO-500/750/1000 User Manual](https://cdn.shopify.com/s/files/1/2643/6080/files/CBO_500-750-1000_User_Manual_120225_English_V1_-_Digital.pdf?v=1787951517) — 10 inches at sides and back, 18 above, 30 below, 30 inches beside and 36 in front of the door; do not pack clearances with insulation; masonry or metal base for a 350-pound oven on a 4-inch reinforced slab; layer order and dry insulation boards; [Alfa Forni — User manual, domestic ovens (North America)](https://www.alfaforni.com/download/user-manual/home/user_manual_domestic_ovens-NA.pdf) — Never fill a required clearance with insulation; under a roof or pergola the oven needs a UL 103HT double-wall chimney; [Marra Forni — Static oven manual (Rev. 5-2026)](https://marraforni.com/wp/wp-content/uploads/2026/05/Static-Manual-Marra-Forni-Rev-5-2026.pdf) — 2 inches to combustibles at sides and back; combustible sidewalls 30 inches from the door opening and 36 inches in front; forklift handling and legs anchored into a 4-inch concrete slab ## Roofs, pergolas and eaves above the oven Overhead is where installations most often go wrong, because a pergola or patio roof is usually added for the cook's comfort. Alfresco says its oven must not be placed over, under or next to unprotected combustible construction, and Kalamazoo says never to put its oven beneath an overhead combustible surface. Coyote says its wood oven should not sit under combustible material at any height, and that nothing should be within 10 feet of the top of the chimney cap. A roof also changes the chimney. Alfa's venting guide says the single-wall pipe supplied with its ovens is enough outdoors with no overhead obstructions, but an oven under a roof, a pergola or any ceiling needs a UL 103HT double-wall chimney run through the structure, installed with its own clearances. ### When a covered patio stops counting as outdoors Outdoor gas ovens are certified for outdoor use only, and Kalamazoo spells out what that means. An oven is outdoors with walls on three sides and no roof; with a roof and no more than two walls; or with a roof and three walls if at least 30 percent of the enclosure's perimeter is permanently open. Sliding doors, garage doors, windows and screens do not count as open. A space that fails that test needs a different kind of oven and a vented installation. Source: [Kalamazoo — Artisan Fire Pizza Oven Use and Care Guide (North America)](https://cdn.shopify.com/s/files/1/0957/4006/8119/files/Kalamazoo-Artisan-Fire-Pizza-Oven-Use-and-Care-Guide-North-America-English.pdf) — 6 inches at sides and back, 12 inches above, never under an overhead combustible surface, noncombustible surface extending 9 inches, 36 to 42 inches high, 100-pound oven; definitions of an outdoor installation; [Alfresco — Pizza Oven Care and Use Manual (AXE-PZA)](https://alfrescogrills.com/wp-content/uploads/2021/07/AXE-PZA-CARE-AND-USE-MANUAL-SERIAL-N%C2%B0-18-00000-FORWARD.pdf) — 12 inches from rear exhaust and 1 inch around the base to combustibles; never over, under or next to unprotected combustible construction; never on combustible countertops; built-ins need bottom access and an access door to the shutoff and GFCI; [Coyote — Duomo Wood Fired Pizza Oven Owner's Manual](https://coyoteoutdoor.cdn.prismic.io/coyoteoutdoor/aBI1GfIqRLdaBwbi_Coyote_Wood-Fired_Pizza_Oven_Owners_Manual_2.pdf) — 36 inches to combustibles at sides and rear and 36 inches from the mouth; not under combustible material at any height; nothing within 10 feet of the chimney cap top; wood decks are combustible; [Alfa Forni — User manual, domestic ovens (North America)](https://www.alfaforni.com/download/user-manual/home/user_manual_domestic_ovens-NA.pdf) — Never fill a required clearance with insulation; under a roof or pergola the oven needs a UL 103HT double-wall chimney Close on the insulated stand and hearth slab under a wood-fired pizza oven. ## The stand and hearth under a wood-fired oven A refractory dome is heavy and holds heat for hours, and all of it sits on the stand. Chicago Brick Oven's manual for its CBO-500 says the support base must be masonry or metal, at least as large as the oven's footprint, flat, level and able to carry the oven's 350 pounds plus the finish built around it. Its typical base is two legs of concrete block topped with a 4-inch, steel-reinforced concrete slab, and it warns that the base and any framing around the oven must be noncombustible and never made of wood. Commercial domes are heavier still. Marra Forni's manual covers moving its ovens by forklift from the sides and anchoring the stand's legs into a 4-inch concrete slab, and asks that a floor outline be marked first so the full circumference of the oven fits the space. ### Insulation under the floor is not optional Chicago Brick Oven's answer to whether a concrete or masonry base still needs insulation is yes: a noncombustible base does not replace the boards specified under the hearth or the blanket over the dome. Without them the slab soaks heat away from the cooking floor, and the heat keeps traveling into the stand. The manual stacks the layers in a fixed order. - Reinforced concrete slab on block legs - A thin galvannealed steel plate - Insulation boards, cut flush with the front and kept dry - The hearth pieces, laid tight with no mortar or glue beneath - The dome, then the insulating blanket over its whole surface ### Keeping those layers dry Chicago Brick Oven asks that the sub-hearth insulation never be left exposed to the weather and that the decorative finish be built on the support base, not on the boards. Water that reaches the insulation turns to steam on the next hot fire, which is why an installation that lets rain in often ends as a call about a cracked floor. Source: [Chicago Brick Oven — CBO-500/750/1000 User Manual](https://cdn.shopify.com/s/files/1/2643/6080/files/CBO_500-750-1000_User_Manual_120225_English_V1_-_Digital.pdf?v=1787951517) — 10 inches at sides and back, 18 above, 30 below, 30 inches beside and 36 in front of the door; do not pack clearances with insulation; masonry or metal base for a 350-pound oven on a 4-inch reinforced slab; layer order and dry insulation boards; [Marra Forni — Static oven manual (Rev. 5-2026)](https://marraforni.com/wp/wp-content/uploads/2026/05/Static-Manual-Marra-Forni-Rev-5-2026.pdf) — 2 inches to combustibles at sides and back; combustible sidewalls 30 inches from the door opening and 36 inches in front; forklift handling and legs anchored into a 4-inch concrete slab ## The counter under an outdoor gas pizza oven Countertop gas ovens push heat downward through their base, so the surface below matters. Alfresco says its oven must never run on combustible counters and names laminate, solid-surface and quartz composite materials, wood and anything with combustible binders or finishes. Kalamazoo asks for a noncombustible surface that can carry its roughly 100-pound oven without tipping or sliding, extends 9 inches past the sides and back, and stands 36 to 42 inches high. Once an oven is built into masonry it can no longer be lifted out for service. Alfresco requires access to the bottom of a built-in unit and recommends an access door so the gas shutoff and the GFCI receptacle can be reached. Planning that door at build time saves a demolition later. - Stone, concrete, tile over a noncombustible base or steel, not laminate or quartz composite - Strong enough for the oven's weight without flexing or sliding - Deep and wide enough to leave the margin the maker asks for around the oven - The space under the oven left open so combustion air can reach the burner - An access door to the gas shutoff and the receptacle on a built-in Source: [Kalamazoo — Artisan Fire Pizza Oven Use and Care Guide (North America)](https://cdn.shopify.com/s/files/1/0957/4006/8119/files/Kalamazoo-Artisan-Fire-Pizza-Oven-Use-and-Care-Guide-North-America-English.pdf) — 6 inches at sides and back, 12 inches above, never under an overhead combustible surface, noncombustible surface extending 9 inches, 36 to 42 inches high, 100-pound oven; definitions of an outdoor installation; [Alfresco — Pizza Oven Care and Use Manual (AXE-PZA)](https://alfrescogrills.com/wp-content/uploads/2021/07/AXE-PZA-CARE-AND-USE-MANUAL-SERIAL-N%C2%B0-18-00000-FORWARD.pdf) — 12 inches from rear exhaust and 1 inch around the base to combustibles; never over, under or next to unprotected combustible construction; never on combustible countertops; built-ins need bottom access and an access door to the shutoff and GFCI ## Floors and walls around a deck oven or conveyor oven Pizzeria ovens are set close to walls but need a floor that cannot burn. Middleby Marshall's conveyor manual allows zero clearance to side and rear walls for its PS638 series, yet requires noncombustible flooring with nothing combustible beneath it, extending at least 12 inches beyond the oven on every side. Bakers Pride lists 3 inches to combustible construction on the left and rear of its gas deck ovens and 1 inch on the right, and says nothing may be stored on top of or under the oven. Air around the base matters as much as distance. Blodgett keeps 6 inches clear on each side, the back and underneath its 1060 deck oven, plus 12 inches on the left for service, and says the oven must not sit on a curb base or be sealed to a wall; pilot outages or yellow, floating burner flames are its signs of too little air. Source: [Middleby Marshall — PS638 Series Owner's Operating and Installation Manual](https://www.middlebymarshall.com/wp-content/uploads/2021/07/74617-PS638-Owners-Manual.pdf) — Zero clearance to side and rear walls; noncombustible floor extending at least 12 inches beyond the oven on all sides; [Bakers Pride — Floor model gas deck oven operation manual](https://web.archive.org/web/20180921212313/http://www.bakerspride.com:80/docs/default-source/manuals/deck-ovens/100-200-300-400-600-800-125-805-series-deck-ovens-ops-manual.pdf?sfvrsn=8) — 3 inches left and rear and 1 inch right to combustible construction; store nothing on top of or under the oven; [Blodgett — 1060 Gas Deck Oven installation, operation and maintenance manual](https://www.blodgett.com/custom/PDF/manuals/1060-man-english.pdf) — 6 inches at each side, back and bottom, 12 inches left for service; no curb base or sealing to a wall; pilot outages or yellow floating flames show a lack of secondary air ## Where to stop Measuring clearances, moving a stand, cutting into a masonry surround, lifting a dome or a deck oven and running a chimney through a roof belong to the oven's installer, a mason or a chimney professional working from the maker's manual and local permits. An owner who finds scorching, a warm wall or a cracked stand turns the oven off and books an inspection. Written by [PizzaOvenRepair.center technical team](https://pizzaovenrepair.center/authors/technical-team/). Technicians servicing backyard pizza ovens and pizzeria deck and conveyor ovens, drawing on field visits and oven manuals. Sources: [Kalamazoo — Artisan Fire Pizza Oven Use and Care Guide (North America)](https://cdn.shopify.com/s/files/1/0957/4006/8119/files/Kalamazoo-Artisan-Fire-Pizza-Oven-Use-and-Care-Guide-North-America-English.pdf) · [Alfresco — Pizza Oven Care and Use Manual (AXE-PZA)](https://alfrescogrills.com/wp-content/uploads/2021/07/AXE-PZA-CARE-AND-USE-MANUAL-SERIAL-N%C2%B0-18-00000-FORWARD.pdf) · [Coyote — Duomo Wood Fired Pizza Oven Owner's Manual](https://coyoteoutdoor.cdn.prismic.io/coyoteoutdoor/aBI1GfIqRLdaBwbi_Coyote_Wood-Fired_Pizza_Oven_Owners_Manual_2.pdf) · [Chicago Brick Oven — CBO-500/750/1000 User Manual](https://cdn.shopify.com/s/files/1/2643/6080/files/CBO_500-750-1000_User_Manual_120225_English_V1_-_Digital.pdf?v=1787951517) · [Chicago Brick Oven — Frequently asked questions](https://chicagobrickoven.com/pages/faq) · [Alfa Forni — User manual, domestic ovens (North America)](https://www.alfaforni.com/download/user-manual/home/user_manual_domestic_ovens-NA.pdf) · [Marra Forni — Static oven manual (Rev. 5-2026)](https://marraforni.com/wp/wp-content/uploads/2026/05/Static-Manual-Marra-Forni-Rev-5-2026.pdf) · [Middleby Marshall — PS638 Series Owner's Operating and Installation Manual](https://www.middlebymarshall.com/wp-content/uploads/2021/07/74617-PS638-Owners-Manual.pdf) · [Bakers Pride — Floor model gas deck oven operation manual](https://web.archive.org/web/20180921212313/http://www.bakerspride.com:80/docs/default-source/manuals/deck-ovens/100-200-300-400-600-800-125-805-series-deck-ovens-ops-manual.pdf?sfvrsn=8) · [Blodgett — 1060 Gas Deck Oven installation, operation and maintenance manual](https://www.blodgett.com/custom/PDF/manuals/1060-man-english.pdf) For the heart of your home. ## Questions owners ask. ### Can a pizza oven go on a wooden deck? Not directly. Coyote lists wood and treated wood decks as combustible, and most makers require a noncombustible surface under the oven and around its mouth. ### Is a stone countertop enough under a countertop gas oven? Natural stone and concrete are noncombustible, but Alfresco rules out quartz composites and laminates. Check the substrate beneath the top as well. ### Do the pizza oven clearances change if the wall is brick? Often. Several makers publish smaller distances to noncombustible walls, but air gaps must stay open and never be filled with insulation. ### Who checks the clearances on a new build? The installer works from the maker's manual, and the local building or fire department may inspect. Chicago Brick Oven tells owners to contact those officials first. ## The problems behind it. Each has a page of its own: what it usually means and the causes in the order worth checking. [All 17 problems](https://pizzaovenrepair.center/problems/) Problem ### Pizza Oven Floor Cracked: Split Tiles, Lifted Bricks, Crumbling Stone 6 causes, cheapest first Problem ### Pizza Oven Dome Cracked Inside or Out After Rain or a Big Fire 6 causes, cheapest first Problem ### Pizza Oven Not Getting Hot Enough to Bake a Crisp Crust 7 causes, cheapest first Problem ### Pizza Oven Pilot Won't Stay Lit Once the Knob Is Released 6 causes, cheapest first ## When it needs a technician. The repairs on the right are where this guide ends when the checks do not settle it. ### Pizza oven floor and dome repair Cracked or spalled hearth bricks and stones reset or replaced, dome and arch cracks packed and sealed, and the oven cured back up slowly. ### Pizza oven diagnostic visit One visit to learn why the pizza oven will not light, heat, hold temperature or draw: gas, flame, stone, chimney, belt and controls each checked. ### Pizza oven cleaning and safety inspection A full cleaning of the pizza oven's burners, floor, fingers, chimney path and vents, with a gas leak check, flame check and written safety report. ## More in installation and setup. Keeping a pizza oven clear of walls, eaves and anything that burns, the hearth and stand it sits on, how its flue is run, and the gas and power a pizzeria oven needs. [The whole section](https://pizzaovenrepair.center/guides/installation-and-setup/) Clearances, the hearth under it, the flue and the fuel ### Venting a pizza oven: chimney height, offsets, hoods and makeup air When the supplied stack is enough, what changes under a roof, how deck and conveyor ovens are vented under a hood or through the roof, wood fires indoors and the signs of a weak draft. Clearances, the hearth under it, the flue and the fuel ### Gas and power for a pizzeria oven: what the rating plate asks of the building Manifold pressures, shutoffs and restrained connectors for gas decks, three-phase supplies and disconnects for electric conveyors, start-up tests and who handles each part of the hookup. Guides ### All 18 guides Six sections, by what you are trying to find out. --- **[Read on the site: Clearances and the hearth under a pizza oven: walls, roofs and the insulated floor](https://pizzaovenrepair.center/guides/clearances-and-the-hearth-under-an-oven/)** **[Book a visit with PizzaOvenRepair.center](https://pizzaovenrepair.center/schedule/)**