This article explains what is needed to prepare the project site, general fireplace mantel anatomy, tools necessary, and how to install a cast stone fireplace mantel. If you would like to watch a quick video of how to install a cast stone fireplace, DeVinci has created a brand new installation guide that covers all the steps of this blog post and more, check out the video here!

How to Install a Cast Stone Fireplace

At this point during your project, you should have already uncrated your delivered cast stone fireplace mantel. If you are having trouble uncrating your surround, please see this blog before continuing to learn how to install your fireplace mantel.

To ensure that you know exactly what pieces are which during installation, please review the Fireplace Anatomy Cheat Sheet below:

Cast Stone Fireplace Anatomy

Although DeVinci Cast Stone provides some installation accessories, you will need to provide a few things as well. Please follow this link to our blog on items needed to install your cast stone fireplace mantel surround.

Once you have collected all the installation accessories needed, you can begin preparing the site for installation of your cast stone fireplace mantel.

 

Site Preparation

  • Clear away any furniture that may be in the way during installation. You may want to cover any furniture still in the room, and your floors if the finished floor has already been installed to prevent any accidents that may occur from ruining any of the existing furnishings.
  • Confirm that the surface which you plan to install your surround is clean, capable of supporting the final product weight, and is level.
  • Find and mark the center line of the firebox for your reference during installation.

  • Using a level, transfer the center line up the wall, past the highest point of the fireplace mantel. You may want to mark the center line with a “C” to avoid confusion later.

  • Use your stud finder to locate the studs surround the firebox. Use your level to extend the stud “marks” above the highest point of the mantel. These lines will identify attaching points during the build.

 

  • Whenever possible, the mounting brackets should be attached to the wall at stud locations. When studs are not accessible, mounting brackets should be attached to the wall using Toggle-Lock Heavy Duty Drywall Anchors.

Installing the Hearth

All DIY/Quick Ship mantels are shipped with a three-piece hearth.Should you not need these stones, you can simply discard them, or use them at their own discretion.

Fireplace Codes generally require that combustible materials (wood flooring, carpeting, etc.) shall be a minimum of twenty inches from the front of the firebox. DeVinci’s hearths are designed to exceed these requirements. The installer is responsible for adhering with local code requirements.

1. To begin installation on the hearth, locate the center hearth stone, and mark the center line of the piece.

2. Then shim the mounting surface as necessary to gain appropriate base height and level side to side and front to back.

3. Apply a generous amount of mastic to the mounting surface.

4. Position the hearth’s center stone against the wall aligning the center line of the firebox with the center line of the stone.

5. Position right and left hearth stones with each separated from the middle stone using one-quarter inch of grout spacers. These have been provided to you by DeVinci Cast Stone.

6. Compress the mastic to level hearth stones from side to side, front to back, and the appropriate height.

 

Installing the Filler Panels

 

Fireplace surrounds are assembled from the bottom up. The next component installed would be the bottom filler panel if one is used. In some applications, it is used to cover the area between the floor or hearth and the firebox, or it can serve as an ash stop. In others, it is not used and can be discarded. Prior to installation, the bottom filler panel may need to be cut to the appropriate height and width.

7. Locate and mark the center of the bottom filler panel.

8. Position one-quarter inch of grout spacers on hearth or floor below outer edges of the fire box.

9. Apply mastic to the back of the filler panel and to the surface it will sit on.

10. Align the center mark on the filler panel with the center line noted on the wall or hearth, set it on top of the grout spacers positioned earlier and press the panel against the wall.

11. Check and adjust level as needed and secure the panel to the wall at its right and left outer edges using J-02 brackets.

 

Wall brackets must always be located such that they will be completely covered by later panels. They are secured to the wall using a Tapcon at a stud point or with a heavy-duty wall toggle. They are secured to the stone components by drilling a 3/16” hole and inserting a ¼” Tapcon.

 

Prior to installation, the side filler panels may need to be cut to the appropriate height and width.

12. Position one-quarter inch of grout spacers and mastic on both ends of the bottom filler panel by the J-02 brackets.

13. Apply mastic to the back of one of the side filler panels.

14. Align its inside edge with firebox, set it on top of the grout spacers positioned earlier with its bottom edge secured within the J-02 bracket holding the bottom panel and press it against the wall.

15. Check and adjust level as needed and secure the panel to the wall at its top edge using a J-02 bracket.

16. Install the other side filler panel in the same manner.

17. Make any adjustments necessary to assure that both side filler panels are leveled both vertically and at their tops in relation to one another.

 

Prior to installation, the top filler panel may need to be cut to the appropriate height and width.

 

18. Mark the horizontal center on the top edge of the top filler panel.

19. Position one-quarter inch of grout spacers and mastic on the top of both side filler panels by the J-02 brackets.

20. Apply mastic to the back of the panel.

21. Align its center with the center mark on the wall and set it on top of the grout spacers positioned earlier with its bottom edge secured within the J-02 bracket holding the side filler panels and press it against the wall.

22. Check and adjust level as needed and secure the panel to the wall at its top edge using two Z-01 brackets.

23. Clean any extraneous mastic off installed panels.

 

Installing Legs and Header/Mantel Shelf

24. Referring to the installation drawing, with a pencil, lightly mark the locations of the inside edge of both legs on the side filler panels.

25. Referring to the installation drawing for placement, install a J-01 Leg & Mantle mounting bracket in two locations and secure them to the wall and the hearth or floor.

 

When installing a J-01 Leg & Mantle mounting bracket, two Tapcons must be installed

through the horizontal surface into the floor or stone and at least two Tapcons or screws into the wall.

 

26. Place one-quarter inch of grout spacers on both sides of each J-01 Leg & Mantle mounting bracket.

 

The bottom of each leg is slotted to accommodate the toe of the J-01 Leg & Mantle mounting bracket.

 

27. For one leg, apply a generous amount of mastic between the grout spacers and a small amount on the back surfaces where the leg will meet the wall.

28. Carefully lift the leg in place so that its bottom slot fits over the toe of the J-01 Leg & Mantle mounting bracket and its inside edge aligns with the marks on the side filler panel and press leg to the wall.

29. Assure placement and vertical level and secure leg at top with a J-01 Leg & Mantle Bracket

 

At both sides of the Mantle Shelf / Header where it meets the top of the leg, it is slotted to

accommodate the toe of the J-01 Leg & Mantle mounting bracket.

 

30. Install opposing leg in the same manner.

31. Check level across tops of legs and make any necessary adjustment placing shims on lower grout spacers.

32. On the top of the Mantle Shelf / Header, make a small mark at the back center.

 

Please Note: Some mantle shelves / headers include an additional installation cleat (CL). (For those units skip to step 37.)

 

33. Place one-quarter inch of grout spacers and mastic on the top of each leg.

34. Put a small amount of mastic on the back surfaces of the mantle shelf / header that will meet the wall.

35. Carefully lift the mantle shelf / header in place so that it is aligned with the center line on the wall and its bottom slots fit over the toes of the J-01 Leg & Mantle mounting brackets on the top of each of the legs.

36. Check level side to side and front to back. Assure that top of header is even with top of legs.

37. Referring to the installation drawing for the appropriate dimension, measure up from the top of one of the legs and make a mark on the wall.

38. Using a level, scribe a horizontal line that approximately spans the width of the fireplace surround.

39. On the bottom (small, flat edge) of the cleat (CL), measure and mark the middle.

40. With the low edge of the chamfer on the top of the cleat (CL) facing the wall and its bottom edge centered on and aligned it with the horizontal line, Attach the cleat (CL) to the wall at three stud locations.

41. Place one-quarter inch of grout spacers and mastic on the top of each leg.

42. Apply mastic to the top of the installation cleat (CL).

43. Carefully lift the mantle shelf / header in place so that it is aligned with the center line on the wall, its bottom slots fit over the toes of the J-01 Leg & Mantle mounting brackets on the top of each of the legs and it rests on the installation cleat (CL).

44. Check level side to side and front to back. Assure that top of header is even with top of legs.

 

Grouting the Surround

Always wear eye, hand and skin, breathing and hearing protectors appropriate for the procedure being performed. Grout can stain floors, walls and ceilings. Take necessary precautions to cover areas surrounding the work space.

 

45. Carefully tape both sides of areas to be grouted.

When taping, set tape back 1/32” to 1/16” from opening to provide a slight overlap.

This aids in ease of finishing the grout lines. Added care given to the taping process will greatly enhance the finished product.

46. Once taping is complete, apply drop cloths and shielding to all surfaces that might be stained by grout.

 

Please Note: Only prepare grout in a quantity that can be used in approximately one hour.

Reserve a portion of the components for possible future patching needs.

47. Prepare Grout

•In a clean container, prepare Water/Polyplex mixture. (Eight parts water to one-part Polyplex).
•Mix water/Polyplex mixture into screened grout to attain the correct consistency.
•After initial mixing is complete, allow grout to rest for approximately five minutes and then re-agitate. This will break the grout’s initial bond and make it easier to work in the grout bags.

 

Grout should be mixed to the consistency of thick pancake batter.

 

A grout bag should be used during the grouting process. To prepare the grout bag, cut the small end of the bag so that the opening is approximately 3/8” in diameter. Rinse the interior of the bag with clean water to prevent sticking of the grout. Fill the bag half to two-thirds full and twist top to seal the bag. The bag can be squeezed to expel the grout from the small end and the top twisted as necessary as the contents are used.

48. Fill grout bag.

 

It’s always good to have a container of clean water and sponge available for cleaning up spatters throughout the grouting process.

 

49. Begin grouting fireplace surround from bottom, working up.

50. Fill grout joint liberally and work first course back into joint approximately ¼” to ½” with tuck pointing trowel or similar tool.

 

Should grout mixture begin to stiffen, rework it with mixer to return it to a usable state.

DO NOT add additional water unless mixing does not return grout to its initial consistency.

51. Apply second course of grout leaving it stand proud (well out from the joint).

52. Continue the two-course grouting method throughout.

53. Allow grout to set up until it provides resistance to slight finger pressure and grout does not transfer to finger when touched.

54. Using a pointing tool with medium pressure and a sliding motion, press the grout into the grout lines. The blade of the tool should be flat and wider than the joint width and free of rust. A mastic trowel will do perfectly. This helps reduce chances of the mortar cracking later. The pressure applied pushes the mortar farther into the joint and eliminates any unseen voids.

55. Allow the grout to dry for approximately a half hour and then holding the blade of your grouting tool or mastic knife perpendicular to the grout lines and using short shaving motions, work grout flush with tape.

56. Once flush, the joints can be tooled smooth with a trowel, brushed with a horsehair masonry brush or rubbed with a piece of carpet.

57. Remove tape touching up minor inconsistencies as you go with flat bladed tool.

 

When all tape has been removed, the grout surface can be touched up by brushing surface lightly with damp sponge. Rinse sponge frequently in clean water container and wring out excess water. A piece of carpet can be used as well for a bit more texture.

 

58. Clean tools, equipment and work area.

Congratulations on the successful installation of your DeVinci Mantel!

The next step involved in installing your DeVinci Cast Stone fireplace mantel is deciding whether you will seal your surround. Please see this blog for information on protecting and cleaning your surround when accidents occur, resulting in stubborn stains. Should you need information on patching due to unforeseen mishaps, please visit this page on our website or give us a call!

Please do not hesitate to give one of our customer service representatives a call should you have any questions or concerns during the installation, or while learning how to install your DeVinci Cast Stone fireplace mantel. You can also submit a contact request form via our website should your preferred method of contact be by email. Our team is prepared to assist you in any way they possibly can!

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