If you’ve been researching outdoor kitchen construction in Oklahoma, you’ve likely seen the term “CMU block” used by professional contractors — including VistaScapes Design. Many homeowners aren’t familiar with the term and wonder if it’s different from the “concrete blocks” they’ve seen at hardware stores. Here’s a clear explanation of what CMU block is, why it’s the right choice for outdoor kitchens, and what the alternatives look like.
What Is CMU Block?
CMU stands for Concrete Masonry Unit — the technical term for what most people call a “cinder block” or “concrete block.” It’s the same material. A CMU is a hollow rectangular block made from Portland cement, sand, water, and aggregate (crushed stone or cinder), cast in standardized dimensions and cured to high compressive strength.
The standard CMU is 8 inches wide x 8 inches tall x 16 inches long. This standardized size is why “CMU block” and “concrete block” refer to the same product — “CMU” is simply the building industry’s technical name for the material.
Why CMU Block Is the Standard for Outdoor Kitchen Construction
Structural Strength
CMU block has a compressive strength of 1,900 to 3,000 psi or more depending on mix design — far stronger than what a residential outdoor kitchen structure experiences from vertical loads. The mortar-bonded CMU structure creates a monolithic assembly that resists movement, settling, and racking forces that alternative frame systems cannot match.
Moisture Resistance
Oklahoma’s outdoor environment subjects any structure to rain, humidity, freeze-thaw cycling, and direct water exposure. CMU block handles moisture without the rust, rot, or delamination that affects steel stud, wood, and cement board frame systems over time. When finished with a masonry sealer, CMU block outdoor kitchens maintain their structural integrity for decades without the moisture-related failures that plague alternative frame materials.
Fire Rating
CMU block is inherently fire-rated — concrete doesn’t burn, char, or contribute to flame spread. This matters directly next to a grill, pizza oven, or outdoor fireplace where frame material fire resistance is a genuine safety consideration. Steel stud and cement board frames are fire-resistant but not fire-rated in the same way as solid CMU construction.
Thermal Mass
CMU block absorbs and slowly releases heat — useful in an outdoor kitchen context because the structure moderates the immediate environment around the cooking area. The thermal mass effect is modest but real, and it works in your favor on cooler Oklahoma evenings when the retained warmth from an active grill keeps the outdoor kitchen comfortable longer.
What Are the Alternatives to CMU Block?
Steel Stud Frame with Cement Board
Light gauge steel studs covered in cement board (Hardiebacker or similar) are used by some contractors as an outdoor kitchen frame because they’re faster to build and lighter than CMU block. The problem in Oklahoma: steel studs rust at the bottom plates and fasteners when moisture infiltrates — and moisture always infiltrates over time. Cement board can delaminate. The assembly lacks the structural monolithic rigidity of CMU block and shows wear within 5 to 10 years that CMU structures don’t.
Prefabricated Outdoor Kitchen Frames
Pre-built outdoor kitchen frames — steel or aluminum chassis with panels attached — are available at big-box stores and from online retailers. These are not comparable to CMU block construction. They’re appropriate for portable or temporary outdoor kitchen setups, not for permanent outdoor kitchens intended to last for decades in Oklahoma’s climate.
Wood Frame
Pressure-treated wood frames are sometimes used for outdoor kitchen structures, particularly in covered areas. Wood requires sealing and maintenance to resist Oklahoma’s moisture cycling, and it cannot be used directly adjacent to high-heat appliances without fire-rated separation. Wood frames for outdoor kitchens are most appropriate for covered bar areas or casual outdoor kitchen setups where appliance heat exposure is minimal.
Why VistaScapes Design Uses CMU Block
We use CMU block for every permanent outdoor kitchen we build because it’s the professional standard — the same material used in commercial outdoor kitchens, resort installations, and the highest-quality residential outdoor living projects in Oklahoma and nationwide. It costs more and takes longer to build than alternative frame systems, but it’s the right material for a structure you expect to last the lifetime of your home.
Call VistaScapes Design at (918) 779-1317 or visit 413 N Walnut Ave Suite A, Broken Arrow, OK 74012 to discuss your outdoor kitchen project in Broken Arrow, Tulsa, or anywhere in the surrounding area.
