Mason-Lite 33" Pre-Cast Masonry Firebox Kit

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Have you ever dreamed of the radiant warmth of a masonry fireplace in your bedroom? Or, do you dream of an outdoor fireplace where you can gather together with friends and loved ones? Dreams can come true with Mason-Lite masonry fireplaces. Our factory-built masonry fireboxes are affordable, easy to handle, and consistent in quality. A masonry fireplace adds luxury and increases the value of your home.

Recreating the tradition of the hearth and the elegance & romance of the flame, Mason-Lite captures the essence of the fireplace masonry artists have been crafting for centuries. And, with a proven history of superior quality, lightweight fireplaces for indoor and outdoor projects, it’s no wonder Mason-Lite is one of the industry leaders of modular concrete fireplaces.

At Mason-Lite, we use the finest aggregate materials available to build our lightweight modular concrete fireplaces. One of the main ingredients is pumice, a natural-fired volcanic rock with tremendous strength.

Its lightweight attributes are second to none, and because of its pre-fired beginnings, pumice retains heat better than any natural aggregate available. The best sources for USA pumice are in the western states, convenient to Mason-Lite’s California-based production facilities. Pumice is formed when gas-rich, frothy magma rapidly cools, creating air pockets that contribute to its remarkable lightweight properties.

Because it is only half the weight and half the cost of traditional masonry fireplaces, Mason-Lite Lightweight Masonry Fireplace Systems help you realize your dream of having a fireplace in your master bedroom, upstairs retreat, or even your outdoor patio, without major building infrastructure reinforcement. The restful flicker and comfortable glow of the fire will provide you with years of treasured memories.

With the help of ICC-ES, Mason-Lite developed the structural testing and performance criteria (AC375) that would comply with the International Building Code (IBC), the International Residential Code (IRC), and the International Fuel Gas Code (IFGC). This allows building officials throughout the US to confirm that Mason-Lite fireplaces meet these stringent codes.

Why Choose Mason-Lite:

The Perfect Fireplace for space-restricted Projects:

The MFP33 has a finished opening of 30” W x 22.5” H and is a standalone unit that can be built Indoors or Outdoors to burn wood or gas.


  • Available in 33-P39", 44", 49", 63", and 43" See-Thru 
  • Lightweight construction with multiple firebox sizes available
  • Best fit and finish in the industry
  • Available for Indoor/outdoor, wood-burning, natural, and propane gas systems
  • Allowed for multi-story combustible floor installations
  • Superior thermal efficiencies with the highest resistance strength at 28 days
  • Complies and tested with UL 127 & UL 103 chimney component standards
  • Optional herringbone or running bond firebrick panels for easy installation
  • Heat resistant fire tested up to 1700 Degrees Fahrenheit
  • Less expensive shipping and handling costs
  • 50% cheaper than a traditional hand-built masonry fireplace
  • All kit comes complete with Refractory Mortar, Rebar and T-bar
  • Limited Lifetime warranty
  • Made in the U.S.A.



Model MFP33
Finished Opening Dimensions 30" (W) x 21.5" (D) x 22.5" (H)
Total Unit Height 54.5"
Footprint 37" x 28"
Flue Diameter - Class A 12" ID
Clearance to Combustibles* (Sides and Back) 2"
Framing Dimensions 41" (W) x 30" (D) x 56.25" (H)
Floor Area (37 x 28) 7.2 sf
Fireplace Weight 1,091 lbs.
Mortar and Rebar 60 lbs.
Ready Mix 150 lbs.
Metal Chimney weight per foot 10 lbs.
Installation Type Flush Installation / Corner / Internal Wall / Full Projection
Warranty Limited lifetime warranty



Options and Accessories

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MFP33SHBL Split Herringbone Brick liner

Mason-Lite offers true firebrick panels for quick and easy installation.

Two-color options: Standard Buff and Red

MFP33FRBL Full Running Bond Brick liner

Mason-Lite offers true firebrick panels for quick and easy installation.

Two-color options: Standard Buff and Red

MFP33SRBL Split Running Bond Brick liner

Mason-Lite offers true firebrick panels for quick and easy installation.

Two-color options: Standard Buff and Red

MFPB33 6" Structural Metal Base

Our 6” and 8” bases are used for installations on combustible floors or second-story applications.

MFP4-AK Combustion Air Kit

Because homes are being built so tight, many jurisdictions are requiring additional outside air to make up for negative air pressure. For convenience, the kit comes pre-drilled for this application.

MFP-Arc Masonry Arch

The masonry arch kit consists of 2 pieces that can easily be mortared in to give a custom look.

MFP33-HK Height Kit

This Height Kit consists of a rear wall and two side walls that will increase the height opening by 8" from the standard opening (giving a Rumford look). With the new size, the opening is sure to check the Chimney Size Chart to ensure proper flu size.

MFP12-AP Anchor Plate/Damper

Dampers are required for indoor applications. Mason-Lite offers several damper options: metal anchor plate/damper for masonry chimney; cast-iron damper (damper blocks included); anchor plate/damper for metal chimney

QWBP-33 or QWBN-33 Burner Set

Pureburn Grate/Burner Set (Natural Gas or Propane)

MFPDS33 Damper Blocks

Damper blocks come as three masonry blocks that are designed to lift a traditional vestal damper so that it fits our standard masonry fireplaces

Note: If using Mason-Lite Firebrick Panels, Damper blocks are not needed.

Premium Chimney Shrouds

Mason Lite’s Decorative steel and copper chimney pots offer an alternative to unsightly factory flue caps and terminations, improving the aesthetics of chimney tops


Masonry Chimney Systems

Mason-Lite refractory chimney system may be used on MFP33, MFP39, MFP44, and MFP49 with a maximum system height of 30' without additional support.

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Click Here to Shop for Masonry-Chimney System Options

Class A Air-Cooled Metal Chimney System

DuraChimney® II is an exceptional factory-built alternative to pre-fabricated masonry chimneys.DuraChimney® II is a unitized, lightweight design that eliminates the need for field assembly of pipe sections, allowing for faster installation.

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Click Here to Shop for Class A UL103 Chimney Systems




Attention: You may need a residential building permit to install a Mason-Lite Fireplace. Consult local jurisdictions before you get started!