How to Clay Line a Fire Box
An attempt at making a fire to cook or heat without some sort of container for the fire can be both difficult and somewhat dangerous. Fire, under dozens of different circumstances such as the kind of combustible material or the drafts in and around the fire, is an element deserving respect. Indoors, of course, fire must be contained, and even an outdoor fire deserves some restraint unless it is intended to be used for a limited time only. Building a safe and useful backyard fireplace is a satisfying task for the handy homeowner.
Things You'll Need
- Concrete pad
- Masonry materials
- Mortar for masonry
- Containers for mixing mortar
- Firebricks
- Refractory mortar
- Trowel
- Level
Instructions
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Build the outside of the firebox according to an approved plan with a fire-resistant masonry material such as red clay bricks, cement block, natural stone, or synthetic stone on a level concrete foundation. The outer shell of the fireplace should be six inches thick in order to maximize safety.
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Line the inner walls of the firebox with firebrick, leaving a 1/4 to 1/2 inch space between the fireclay bricks and the outer walls of the firebox. Firebrick joints should be no more than 1/4 inch and must be mortared with a combination of medium duty refractory mortar. and no more than 20% ordinary cement. The space between the outerwalls and the fireclay walls must be grouted or mortared as the inner wall is built. Adding the two-inch firebrick to the width of the outerwalls should make the walls a total of at least eight inches thick but the firebrick may or may not reach the top of the outer walls.
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Finish the outer walls of the firebox by adding a layer of the building material, brick or stone, to the ends of each wall, completely covering the firebrick ends. Depending on how the firebrick is arranged inside the firebox, a grate may be easily suspended by resting it atop the firebricks.
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Tips & Warnings
Buy fireclay products such as brick and mortar at large housewares stores, building supply or refractory supply stores.
Buy only bricks and mortar from selections of products intended for use in fireboxes.
Refractory products are manufactured from high temperature resistant materials that don't expand or collapse when hot.
In the case of natural stone used in an outdoor fireplace, mortar is not always necessary. Other materials may be mortared with ordinary cement.
Digging river clay to form a lining for a firebox is not recommended, though it may suffice for a temporary cooking or heating arrangement.
Be aware that only fireclay bricks made of fireclay plus water and formed under extreme pressure are truly fire proof and will not crack, explode or crumble when exposed to high heat.
This kind of masonry firebox or fireplace is not intended for the kinds of fires hot enough for blacksmithing, other metal work or glass work.
References
- Photo Credit Tanya Constantine/Photodisc/Getty Images
