Framing and Sub-Flooring - Do I need more support??

So here is the situation:

I have an area in my living room that we put a new stove/fireplace (an RSF Topaz) in. It is not a chimney fireplace but more a fire box with a stovepipe. Around the firebox we are framing with regular 2x4 studs and then going to sheet this with durock and then have someone come in and lay fake river rock on top of that. I am wondering if my subfloor/joists will support the weight or if I need some more support beneath the floor?

The total weight of this whole project is estimated at 1200-1300 lbs including weight of new stove. The weight is distributed over a 24 sq ft area that covers 3 joists.

The living room is sunken and under the subfloor is 2x12 at 16OC at a span of about 15 feet. One end of the 2x12 is connected to the a main beam with metal hangars and the other end is resting on a 2x4 stub wall that is itself sitting on part of the block foundation. The height of the stub wall is about 4 feet.

Thanks for any help. Just don't want to do all this and have issues with too much weight on a floor.

You gave the total sq footage of your new stove area, but not the dimensions of the area. Will your new stove be sitting on the ends of the 2x12's sitting on the stub wall or the end where the hangers are? Need this info to help you. Thanks

It is an area 6 feet across and 4 feet wide (the 6 feet running parallel with the joists). It will actually be right in the middle of the joists.
Thanks!

Since the majority of the weight will be on the center of the joists, I would sister 2x12's to each joist that will have that weight on them. If you don't give them some strength, they will get a sag in them in less then a year. Just my thoughts.

Thanks, I really appreciate the input.
Could I just add a couple of additional joists to strengthen and achieve the same thing? i.e. placing another joist between the existing ones thus making the joists in that area 8" OC?

If I sister the joists does the new board have to go from end to end? I ask this because I would have a hard time making it the exact same length due to the hangar on the one end. It would be like an inch shorter or so.

Thanks!

Yes, you could add 2 more joists. If that is easier it is the thing to do. Good Luck

So here is the situation:

I have an area in my living room that we put a new stove/fireplace (an RSF Topaz) in. It is not a chimney fireplace but more a fire box with a stovepipe. Around the firebox we are framing with regular 2x4 studs and then going to sheet this with durock and then have someone come in and lay fake river rock on top of that. I am wondering if my subfloor/joists will support the weight or if I need some more support beneath the floor?

The total weight of this whole project is estimated at 1200-1300 lbs including weight of new stove. The weight is distributed over a 24 sq ft area that covers 3 joists.

The living room is sunken and under the subfloor is 2x12 at 16OC at a span of about 15 feet. One end of the 2x12 is connected to the a main beam with metal hangars and the other end is resting on a 2x4 stub wall that is itself sitting on part of the block foundation. The height of the stub wall is about 4 feet.

Thanks for any help. Just don't want to do all this and have issues with too much weight on a floor.

I got a problem here with what you are building and how you are building it. Durock is a great product - when it comes to building a bathroom for tile and for protection against moisture.

But in my opinion - it is not the best material to be used in this situation.

I do understand that this stove is a zero clearance stove and can be mounted directly to the wall with no fireproofing. But I have little faith in something that is going to be permanently installed in the wall.

A quote from the factory brochure, "This fireplace is certified for use with 7" ICC Model EXCEL chimney only. The chimney system height from the top of the fireplace must be a minimum of 12 ft."

Anytime I build any addition or install a wood burner, I make sure that I cut away at least 24 inches of wall in every direction and build a fire proof system where nothing metallic touches the wall that could transfer heat to the building materials and possibly cause a fire.

I would double it and I would put several layers under the stove before I installed it.

I would probably cover the Durock with Firecode C drywall in addition to the wall adjacent to the stove and the ceiling above.

Anytime when you are dealing with a stove that can be operated both with open doors and closed, you will have opportunities for sparks to jump out of the firebox - which could potentially start a fire.

I would make sure to build a hearth in front of the stove - at least 5 feet in all directions and I would make sure to build it sturdy enough to be able to support extra logs and the occasional drop of a log on the floor.

If you use a tile and it cracks, you are risking exposing flammable building materials to the fire box and sparks.

Putting a stove that heavy in one spot on the floor, I would probably put some type of cribbing underneath the floor in that area and shore it up.

Just looking at the bare weight of the stove does nothing for total calculations of weight when you have to figure 6 or 8 logs on the hearth and several people standing around the stove.

It will be a focal point in the room, especially when you have parties in the wintertime.