RECOMMENDED PRACTICES FOR MASONRY FIREPLACE AND CHIMNEY CONSTRUCTION - Introduction - Size of Fireplace

Oct 24, 2026

Recommended practices for masonry fireplace and chimney construction provide clear guidance to achieve quality, safe, practical installations that meet or exceed local and national building code requirements. The document emphasizes choosing appropriate fireplace dimensions for room performance, then planning key components including the foundation, hearth, firebox, and smoke chamber. It details major construction principles and minimum requirements for non-combustible materials, structural support, and proper placement methods such as firebox, hearth extension, and damper and lintel installation.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages8

Reading Time20 min

AccessFree to download

Introduction

Size of Fireplace

Before We Start

Foundation

Firebox and Hearth

Placement of the Damper and Lintels

Published by the New York State Concrete Masonry Association RECOMMENDED PRACTICES FOR MASONRY FIREPLACE AND CHIMNEY CONSTRUCTION INTRODUCTION A well constructed masonry fireplace adds several elements of interest to the home. Providing for not only a source of warmth, masonry fireplaces add character, charm and value. As a result, housing industry studies have shown that masonry fireplaces are among the top preferences of potential home buyers. The concrete masonry industry offers this Recommended Practice to clarify the design and construction of masonry fireplaces in an effort to assure quality, and safe construction that meets or exceeds the requirements of local and national building codes. Following the guidelines contained in this publication will assure quality, safety, practicality, ease of construction and code compliance. These guidelines are a compilation of information from manufacturers, engineers, contractors, technical agencies and building code officials. Always check with your local code enforcement official prior to construction of your fireplace. SIZE OF FIREPLACE Careful consideration should be given to the size of the fireplace best suited to the room in which it is located. This is important not only from the fireplace’s appearance, but from its operation as well. If it is too small it will not produce a sufficient amount of heat, even though it functions properly. Follow Chart No. 1 as a guide in selection of the size best suited foryour application. After selecting the appropriate size of the fireplace, consideration in planning is necessary for several other important areas such as the foundation, hearth, firebox, and smoke chamber. Some of these important items are expanded upon below. Also see the enclosed drawing details for further clarification. Please read the entire tek spec 3.5 before proceeding with design and construction. CHART NO. 1 Fireplace Opening Size of Room Width in Inches in Feet 24 to 32 32 to 36 36 to 40 40 to 48 48 to 60 48 to 72 10 x 14 12 x 16 12 x 20 14 x 28 16 x 30 20 x 26 BEFORE WE START Masonry fireplaces are site built and offer the unique ability for infinite variability and individual expression. Two specific designs are detailed in this guide, the Standard Fireplace and the Rumford Fireplace. The Standard fireplace (see p. 4-5) has a short firebox with the back wall leaning forward. The Rumford Fireplace (seep. 6-7) is tall with widely splayed sidewalls and an aerodynamic curved throat that improves draft and reduces emissions. The heating ability of the Rumford is legendary. The ease of construction, and the visual appeal of the tall opening makes the Rumford a very popular feature with architectsand home builders. Although there are many design variations that are quite acceptable for masonry fireplaces, the same principles of construction apply to all designs as outlined in this specification. Of particular importance are minimum clearance to combustibles, building codes and specifications of materials. Again please read this entire specification for help to assure a quality fireplace installation. FOUNDATION The foundation consists of concrete footings and masonry walls. Minimum code requirements must be met with respect to foundation and wall design. Unless specifically designed for additional loads, no other part of the structure or adjoining structure should be supported by the chimney. Immediately above the foundation wall, support for the combustion chamber and the extended hearthis provided by a cast in place or precast concrete slab. The forming of the concrete slab requires that openings be included for outside combustion air vents and ash dumps. If a permanent form is used it must be non-combustible,(i.e. steel, slate, or corrugated metal) . The concrete slab must not support the floor system. FIREBOX AND HEARTH All materials used to construct the firebox, hearth, and extension must be complete

FAQs

What is the purpose of the recommended practices for masonry fireplaces and chimneys?

The practices clarify design and construction methods to assure quality, safety, practicality, and code compliance for masonry fireplaces. They compile guidance from manufacturers, engineers, contractors, technical agencies, and building code officials.

How should the fireplace size be selected for a room?

Choose the size based on both appearance and operation. If the fireplace opening is too small, it will not produce sufficient heat even if it functions properly, and the document advises using Chart No. 1 as a guide.

What materials are required for the firebox and hearth?

The firebox, hearth, and extension must use completely non-combustible masonry materials. Brick or stone are commonly used, and combustible elements must never provide support to the hearth or fireplace.

Oct 24, 2026

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