© All Rights Reserved Sandkuhl Clay Works, Inc. 2014-2016
Manufacturer of Ceramic,  Structural Clay and Refractory Products for Construction, Agriculture, Commercial and Industrial Applications Since 1912.
Printable Version(requires Adobe Acrobat) Refractory mortar is required by building code for the construction of the internal components of masonry fireplaces (firebox, smoke dome, throat, flue liners, etc.).  Refractory mortars are available in 2 forms:  Dry Mix and Premix   Dry mix refractory mortar is suited for all aspects of masonry fireplace construction where refractory mortar is required.  Premix refractory mortar can only be used for components that do not come in contact with weather (i.e. firebox) because it will wash out.  Premix refractory mortar should never be used in outdoor fireplace construction. We recommend that firebrick be positioned 4 x 2 x 9 (11mm x 6mm x 23mm) (stretchers) as opposed to shiners laid 2 x 4 x 9 (6mm x 11mm x 23mm) to yield a high quality, geometrically stable and durable firebox (Fig 6 and 7).   Figure 4. Interior Hearth Rough Layout Figure 5.  Examples of Approved Refractory Mortar Brands Table 2a. Interior Hearth Dimensions	  			A	 	B		 C		q	 g       30 Rumford		30		12.5		13.5		57	123 36 Rumford		36		14		13.5		51	129 42 Rumford		42		15		15		48	132 48 Rumford		48		16		18		47	133  Table 2b. Interior Hearth Dimensions	      	                       A		B		 C		q	g       30 Rumford		760 mm	318 mm	343 mm	57	123 36 Rumford		914 mm	356 mm	343 mm	51	129 42 Rumford		1067 mm	381 mm	381 mm	48	132 48 Rumford		1219 mm	406 mm	457 mm	47	133 Figure 3.  Hearth--Plan View 2. Laying the Inner Hearth See Table 2 and Figure 3 for the hearth dimensions that correspond to the Rumford that is being built.  Lay out the fire brick on the prepared foundation base so that the bricks cover the inner hearth and accommodate the walls (Fig 4).  The floor hearth bricks should just cover the area required by the inner floor and side walls.   Mortar inner hearth bricks to the hearth support with an approved refractory mortar using a 1/16 to 1/8 (2-3 mm) joint.  Note: Job site prepared fireclay mixes containing Portland and dry milled fireclay do not meet national or state building codes. They do not resist temperature cycling in this application, nor do they possess the necessary acid resistance for this service.  Approved refractory mortars (Fig. 5) are required for use in mortar joints for the firebox, smoke dome and flue linings in masonry fireplaces.

Rumford Fireplace Installation Instructions

1.  Foundation and Preparation

Prepare the supporting foundation for a Rumford using the same construction practices as for a traditional masonry fireplace.  Figure 1 shows a cross section for a Rumford and how the components fit into the total fireplace.  Table 1 lists the minimum hearth base dimensions required for each size of Rumford. As with all masonry construction, the foundation must be adequately designed to support the weight of the fireplace and chimney.  Some typical construction designs are shown in Figure 2.  Local building codes should be reviewed for specific requirements concerning foundation construction.  For the minimum requirements contained in most building codes please refer to BIA Technical Notes on Brick Construction, Residential Fireplace Design 19.
Figure 1. Side Cross Section of a Rumford Fireplace Table 1a.  Minimum Hearth Base Rough Dimensions Rumford Size		Minimum Width	Minimum Depth1 30 Rumford		4-6			3-8 36 Rumford		5-0			4-0 42 Rumford		5-6			4-0 48 Rumford		6-0			4-4 1Includes outer hearth base 		 Table 1b.  Minimum Hearth Base Rough Dimensions (Metric) Rumford Size		Minimum Width	Minimum Depth1 23 Rumford		137 cm			112 cm 36 Rumford		152 cm			122 cm 42 Rumford		168 cm			122 cm 48 Rumford		183 cm			132 cm 1Includes outer hearth base Figure 6.  Completed Firebox Wall Construction Figure 7. Stretchers (top) vs. Shiners (Bottom) Table 3a. Face Opening		Width		Height 30 Rumford		30		27-32 36 Rumford		36		32-38 42 Rumford		42		38-42 48 Rumford		48		42-48  Table 3b. Face Opening		Width		Height 30 Rumford		762 mm	686-813mm 36 Rumford		914 mm	813-965 mm 42 Rumford		1067 mm	965-1067 mm 48 Rumford		1219 mm	1067-1219 mm

3.  Constructing the Firebox

Construct the walls of the firebox according to the dimensions provided in Table 3 that correspond to the size of the fireplace.  Use approved refractory mortar maintaining 1/16” to 1/8” (2-3mm) joints.  Be sure to use proper back-up behind the firebox with appropriate fill.  75% solid concrete blocks are preferred. Be sure to maintain proper clearances to combustibles throughout construction.  See Appendix A for a summary of clearances and other code considerations.
Figure 8. Setting the Rumford Throat Figure 9. Back Walls of Throat Sitting Flush with Fire Brick

4.  Setting the Rumford Throat

After completion of the firebox walls, set and mortar the throat to the firebox with refractory mortar (Fig. 8). Note that the fire box walls should be flush with the interior of the throat (Fig. 9).  There should be no ledges in the firebox where the throat the brick meet.
For outdoor fireplace construction, a damper is not necessary. Figure 15.  Starting the Chimney from Smoke Dome Table 4.          		Flue Size	       			Transition to Round 30 Rumford		12 Round or 13x13 or 12x12	Not Necessary 36 Rumford	   	12 Round or 13x13 			Not Necessary  42 Rumford	   	15 Round or 13x18		        	Available 48 Rumford	   	18 Round or 16x20		        	Available

7.  Setting the 1st Flue Liner and Building the

Chimney

Using refractory mortar, attach the first flue liner to the smoke dome and proceed with normal chimney construction (Fig. 15).  If using a round flue liner and transition ring, position and mortar the transition piece onto the smoke dome and proceed with normal chimney construction Recommended flue sizes and transition rings are listed in Table 4. Take care that all interior transitions are smooth and free of mortar and other obstructions to eliminate horizontal surfaces onto which creosote might accumulate during operation. For any questions regarding chimney construction details, please refer to BIA Technical Notes 19b.

Appendix A.  Clearance to Combustibles (and other important details to avoid mistakes and code violations)

Note:  for outdoor patio fireplaces building codes normally do not apply.  Check with your local jurisdiction. Framing All combustibles must be a minimum of 2” away from the masonry If the fireplace is on an outside wall, combustibles must be 4” from the masonry. Framing headers must be at a minimum of 3’0” above the top of the fireplace opening as well as 2” away from the masonry. Fireplace Firebrick must be backed up with 75% solid masonry creating walls minimum of 8” thick. The masonry surrounding the smoke chamber must be a minimum of 6” thick measured from the outside to the interior wall. A non-combustible surround must extend a minimum of 6” beyond the interior face of the fireplace. Chimney The size of flue liner is determined by the inside face opening of the fireplace.  The flue cross-sectional area required must be a minimum of 10% of the cross- sectional area of the interior face opening.  If using round flues, 8% cross-sectional area may be used. There must be a minimum of 2” airspace between the outside of the flue liner and the chimney wall. The chimney wall must be a minimum of 4” thick solid masonry. The chimney must terminate a minimum of 3’0” from the roof and a minimum of 2’0” from any higher point within 10’ of the chimney.  Please see Masonry Chimney Construction document for further clarification.
Printable Version(requires Adobe Acrobat) Figure 10.  Building Up the Masonry to Create a Setting Surface of the Damper and Smoke Dome Figure 11.  Setting the Damper Figures 13a and 13b.  Setting the Smoke Dome Smoke Dome Dimensions 	                  H	  Base OD	Base ID	Top OD	Top ID 30 Rumford	       19  13x 35	11x 32	13x 13	11x 11 36 Rumford	       19  13x 35	11x 32	13x 13	11x 11 42 Rumford	       30  13x 35	11x 32	13x 17	11x 15 48 Rumford	       30  15x 35	13x 32	15x 19	13x 17  Smoke Dome Dimensions (mm) 	            H	Base OD	Base ID	Top OD	Top ID 30 Rumford	480	330x890	279x813	330x330	279x279 36 Rumford	480     330x890	279x813	330x330	279x279 42 Rumford	762     330x890	279x813	330x445	279x394 48 Rumford	762     394x890	342x813	394x495	342x432  Figure 14.  Smoke Dome Sections for  a.) 30 & 36 Rumford--2 pieces, b.) 42 Rumford--4 pieces and c.) 48 Rumford--6 pieces a. b. c. 6.  Positioning the Smoke Dome Place the smoke dome onto the prepared flat surface fitting it over the top of the damper.  If necessary, adjust the elevation of the smoke dome to insure that the damper opens and closes properly and clears the sides of the smoke dome.  The position of the smoke dome can be adjusted front to back or left to right in order to line up with the chimney.  Make sure that when the damper is operated that it clears the sides of the smoke dome.  Be sure to mortar the smoke dome to the platform and mortar all sections together (Fig. 13a, 13b and 14). Figure 17.  Fireplace Ready for Surround Installation It is important to make sure that the facing does not drop below the front edge of the throat (Fig 18).  Dropping below this elevation will impede the airflow and possibly create a smoking situation.  Figure 18.  Surround Installation Detail Flue Liner Rumford Smoke Dome Flat Damper Firebox Rumford Throat 8.  The Surround Complete the surround in the same manner as with any other fireplace (Fig. 17).

5.  Preparing a Base and Installing the Flat Damper

Build up the surrounding masonry to match the elevation of the top of the throat (Fig. 10).   Place a steel lentil with the first row of masonry that crosses the front of the throat.  This further supports the masonry over the throat (Fig. 10).  Build up the masonry, preparing a flat surface onto which the damper and smoke dome can be placed and mortared (Fig.11).  When setting the damper (Fig 12), make sure that it will operate properly in conjunction with all surrounding masonry.  Check and correct for any interferences in opening, closing or overall operation of the damper.

7a.  Optional Round Flue Adapter

An adapter piece is available for the 42” and 48” Rumford that will convert the square/rectangle opening on the smoke dome to a round opening that is properly sized for the fireplace (Fig. 16).  To install, simply mortar the adapter to the smoke dome and proceed with normal construction using round flues.
IMPORTANT:  The instructions provided are intended as a guideline for installing the prefabricated Rumford components as a part of a masonry fireplace.  Proper fireplace construction techniques, compliance with building codes and any other requirements are the responsibility of the masonry contractor/installer.  Sandkuhl Clay Works, Inc. is not responsible for any errors or misrepresentations that this instruction document may contain or any construction/finished installation problems that may result. Back to Rumford Home Back to Rumford Home
Figure 16. Rectangle/Square to Round Adapter The 30 and 36 Rumfords do not require an adapter.  A 12 round flue nicely fits the 13x13 opening and can be mortared directly to the 36 smoke dome. Round flue liners, especially in the larger sizes, are significantly less costly and more efficient than the equivalent square/rectangle.  Be sure to compare prices.
© All Rights Reserved Sandkuhl Clay Works, Inc. 2014-2016
Manufacturer of Ceramic, Structural Clay and Refractory Products Since 1912.
Refractory mortar is required by building code for the construction of the internal components of masonry fireplaces (firebox, smoke dome, throat, flue liners, etc.).  Refractory mortars are available in 2 forms:  Dry Mix and Premix   Dry mix refractory mortar is suited for all aspects of masonry fireplace construction where refractory mortar is required.  Premix refractory mortar can only be used for components that do not come in contact with weather (i.e. firebox) because it will wash out.  Premix refractory mortar should never be used in outdoor fireplace construction.

Rumford Fireplace

Installation Instructions

1.  Foundation and Preparation

Prepare the supporting foundation for a Rumford using the same construction practices as for a traditional masonry fireplace.  Figure 1 shows a cross section for a Rumford and how the components fit into the total fireplace.  Table 1 lists the minimum hearth base dimensions required for each size of Rumford. As with all masonry construction, the foundation must be adequately designed to support the weight of the fireplace and chimney.  Some typical construction designs are shown in Figure 2.  Local building codes should be reviewed for specific requirements concerning foundation construction.  For the minimum requirements contained in most building codes please refer to BIA Technical Notes on Brick Construction, Residential Fireplace Design 19.
Figure 1. Side Cross Section of a Rumford Fireplace Table 1a.  Minimum Hearth Base Rough Dimensions Rumford Size		Minimum Width	Minimum Depth1 30 Rumford		4-6			3-8 36 Rumford		5-0			4-0 42 Rumford		5-6			4-0 48 Rumford		6-0			4-4 1Includes outer hearth base 		 Table 1b.  Minimum Hearth Base Rough Dimensions (Metric) Rumford Size		Minimum Width	Minimum Depth1 23 Rumford		137 cm			112 cm 36 Rumford		152 cm			122 cm 42 Rumford		168 cm			122 cm 48 Rumford		183 cm			132 cm 1Includes outer hearth base We recommend that fire brick be positioned 4 x 2 x 9 (11mm x 6mm x 23mm) (stretchers) as opposed to shiners laid 2 x 4 x 9 (6mm x 11mm x 23mm) to yield a high quality, geometrically stable and durable firebox (Fig 6 and 7). Figure 4. Interior Hearth Rough Layout Figure 5.  examples of Approved Refractory Mortar Brands
Table 2a. Interior Hearth Dimensions  A B C q  g      30” Rumford 30” 12.5” 13.5” 57° 123° 36” Rumford 36” 14” 13.5” 51º 129º 42” Rumford 42” 15” 15” 48º 132º 48” Rumford 48” 16” 18” 47º 133º Table 2b. Interior Hearth Dimensions   A B  C q g      30” Rumford 762 mm 318 mm 343 mm 57° 123° 36” Rumford 914 mm 356 mm 343 mm 51º 129º 42” Rumford 1067 mm 381 mm 381 mm 48º 132º 48” Rumford 1219 mm 406 mm 457 mm 47º 133º
Figure 3.  Hearth--Plan View Figure 6.  Completed Firebox Wall Construction Figure 7. Stretchers (top) vs. Shiners (Bottom)
Table 3a. Face Opening Width Height 30” Rumford 30” 27-32” 36” Rumford 36” 32-38” 42” Rumford 42” 38-42” 48” Rumford 48” 42-48” Table 3b. Face Opening Width Height 30” Rumford 762 mm 686-813mm 36” Rumford 914 mm 813-965 mm 42” Rumford 1067 mm 965-1067 mm 48” Rumford 1219 mm 1067-1219 mm

3.  Constructing the Firebox

Construct the walls of the firebox according to the dimensions provided in Table 3 that correspond to the size of the fireplace.  Use approved refractory mortar maintaining 1/16” to 1/8” (2-3mm) joints.  Be sure to use proper back-up behind the firebox with appropriate fill.  75% solid concrete blocks are preferred. Be sure to maintain proper clearances to combustibles throughout construction.  See Appendix A for a summary of clearances and other code considerations.
Figure 8. Setting the Rumford Throat
Figure 9. Back Walls of Throat Sitting Flush with Fire Brick

4.  Setting the Rumford Throat

After completion of the firebox walls, set and mortar the throat to the firebox with refractory mortar (Fig. 8). Note that the fire box walls should be flush with the interior of the throat (Fig. 9).  There should be no ledges in the firebox where the throat the brick meet.
Figure 10.  Building Up the Masonry to Create a Setting Surface of the Damper and Smoke Dome Figure 11.  Setting the Damper

5.  Preparing a Base and Installing the

Flat Damper

Build up the surrounding masonry to match the elevation of the top of the throat (Fig. 10).   Place a steel lentil with the first row of masonry that crosses the front of the throat.  This further supports the masonry over the throat (Fig. 10).  Build up the masonry, preparing a flat surface onto which the damper and smoke dome can be placed and mortared (Fig.11).  When setting the damper (Fig 12), make sure that it will operate properly in conjunction with all surrounding masonry.  Check and correct for any interferences in opening, closing or overall operation of the damper.
Figures 13a and 13b.  Setting the Smoke Dome
Smoke Dome Dimensions                   H   Base OD Base ID Top OD Top ID 30” Rumford        19”  13”x 35” 11”x 32” 13”x 13” 11”x 11” 36” Rumford        19”  13”x 35” 11”x 32” 13”x 13” 11”x 11” 42” Rumford        30”  13”x 35” 11”x 32” 13”x 17½” 11”x 15½” 48” Rumford        30”  15½”x 35” 13½”x 32” 15½”x 19½” 13½”x 17” Smoke Dome Dimensions (mm)             H Base OD Base ID Top OD Top ID 30” Rumford 480 330x890 279x813 330x330 279x279 36” Rumford 480     330x890 279x813 330x330 279x279 42” Rumford 762     330x890 279x813 330x445 279x394 48” Rumford 762     394x890 342x813 394x495 342x432
Figure 14.  Smoke Dome Sections for  a.) 30 & 36 Rumford--2 pieces, b.) 42 Rumford--4 pieces and c.) 48 Rumford--6 pieces a. b. c.

6.  Positioning the Smoke Dome

Place the smoke dome onto the prepared flat surface fitting it over the top of the damper.  If necessary, adjust the elevation of the smoke dome to insure that the damper opens and closes properly and clears the sides of the smoke dome.  The position of the smoke dome can be adjusted front to back or left to right in order to line up with the chimney.  Make sure that when the damper is operated that it clears the sides of the smoke dome.  Be sure to mortar the smoke dome to the platform and mortar all sections together (Fig. 13a, 13b and 14).
For outdoor fireplace construction, a damper is not necessary. Figure 15.  Starting the Chimney from Smoke Dome Table 4.          		Flue Size	       		Transition to Round 30 Rumford		12 Round or 13x13 or 12x12	Not Necessary 36 Rumford	   	12 Round or 13x13 			Not Necessary  42 Rumford	   	15 Round or 13x18		        	Available 48 Rumford	   	18 Round or 16x20		        	Available

7.  Setting the 1st Flue Liner and

Building the Chimney

Using refractory mortar, attach the first flue liner to the smoke dome and proceed with normal chimney construction (Fig. 15).  If using a round flue liner and transition ring, position and mortar the transition piece onto the smoke dome and proceed with normal chimney construction Recommended flue sizes and transition rings are listed in Table 4. Take care that all interior transitions are smooth and free of mortar and other obstructions to eliminate horizontal surfaces onto which creosote might accumulate during operation. For any questions regarding chimney construction details, please refer to BIA Technical Notes 19b.

Appendix A.  Clearance to Combustibles (and other important

details to avoid mistakes and code violations)

Note:  for outdoor patio fireplaces building codes normally do not apply.  Check with your local jurisdiction. Framing All combustibles must be a minimum of 2” away from the masonry If the fireplace is on an outside wall, combustibles must be 4” from the masonry. Framing headers must be at a minimum of 3’0” above the top of the fireplace opening as well as 2” away from the masonry. Fireplace Firebrick must be backed up with 75% solid masonry creating walls minimum of 8” thick. The masonry surrounding the smoke chamber must be a minimum of 6” thick measured from the outside to the interior wall. A non-combustible surround must extend a minimum of 6” beyond the interior face of the fireplace. Chimney The size of flue liner is determined by the inside face opening of the fireplace.  The flue cross-sectional area required must be a minimum of 10% of the cross-sectional area of the interior face opening.  If using round flues, 8% cross-sectional area may be used. There must be a minimum of 2” airspace between the outside of the flue liner and the chimney wall. The chimney wall must be a minimum of 4” thick solid masonry. The chimney must terminate a minimum of 3’0” from the roof and a minimum of 2’0” from any higher point within 10’ of the chimney.  Please see Masonry Chimney Construction document for further clarification.
Printable Version(requires Adobe Acrobat) Figure 17.  Fireplace Ready for Surround Installation It is important to make sure that the facing does not drop below the front edge of the throat (Fig 18).  Dropping below this elevation will impede the airflow and possibly create a smoking situation.  Figure 18.  Surround Installation Detail Flue Liner Rumford Smoke Dome Flat Damper Firebox Rumford Throat 8.  The Surround Complete the surround in the same manner as with any other fireplace (Fig. 17). Figure 16. Rectangle/Square to Round Adapter The 36 Rumford does not require an adapter.  A 12 round flue nicely fits the 13x13 opening and can be mortared directly to the 36 smoke dome. Round flue liners, especially in the larger sizes, are significantly less costly and more efficient than the equivalent square/rectangle.  Be sure to compare prices.

7a.  Optional Round Flue Adapter

An adapter piece is available for the 42” and 48” Rumford that will convert the square/rectangle opening on the smoke dome to a round opening that is properly sized for the fireplace (Fig. 16).  To install, simply mortar the adapter to the smoke dome and proceed with normal construction using round flues.

2. Laying the Inner Hearth

See Table 2 and Figure 3 for the hearth dimensions that correspond to the Rumford that is being built.  Lay out the fire brick on the prepared foundation base so that the bricks cover the inner hearth and accommodate the walls (Fig 4).  The floor hearth bricks should just cover the area required by the inner floor and side walls.   Mortar inner hearth bricks to the hearth support with an approved refractory mortar using a 1/16” to 1/8” (2-3 mm) joint. Note: Job site prepared fireclay mixes containing Portland and dry milled fireclay do not meet national or state building codes. They do not resist temperature cycling in this application, nor do they possess the necessary acid resistance for this service.  Approved refractory mortars (Fig. 5) are required for use in mortar joints for the firebox, smoke dome and flue linings in masonry fireplaces.
IMPORTANT:  The instructions provided are intended as a guideline for installing the prefabricated Rumford components as a part of a masonry fireplace.  Proper fireplace construction techniques, compliance with building codes and any other requirements are the responsibility of the masonry contractor/installer.  Sandkuhl Clay Works, Inc. is not responsible for any errors or misrepresentations that this instruction document may contain or any construction/finished installation problems that may result. Back to Rumford Home Back to Rumford Home