Reinforcing floor for new hearth and wood stove load
I am new to the Forums, a DIY first time home owner. There are no topics on point that I have found in a search. I have a 15 year old cabin with concrete foundation, 2×4 stud walls, 2×6 floor joists in a room 15 feet by 25 feet, and I plan to install a 300 lb wood stove over a 6 inch thick stone hearth in mortar bed over steel studs and concrete board in the corner. Windows are in the walls approximately 36 inches from the corner. Hearth dimensions will be approximately 40 square feet, diamond shape with squared front. I have considered pouring one or two concrete post piers to install an 8 foot 4×8 beam under the joists diagonally from the corner out to 2 feet beyond the hearth front edge in the room to support the weight and reduce sag and bounce in the floor. First, is this necesary to support the added weight? Second, is the concept sound and any tips for how to construct the supprting beam are greatly appreciated.
Replies
hey butterfly, welcome.
there are several things that one takes into account when considering something like you are proposing. i would recommend the added support. dig footers, set your beam and support them with timbers or steel columns.
2x6 floor joist are very inadequate for most applications. if you have 2x6 joist spanning 15' with no support breaking that span, you should look at adding some.
40 square feet of 6" thick
40 square feet of 6" thick stone hearth will weigh ~ 3000 lb.
The floor will require reinforcement. I would place the beams for the hearth support diagonally across the corner, supported at the foundation walls, with additional posts and footings in middle as required.
If the floor has bounce, you need additional support to cut down on the span of the floor joists. Is there a beam in the middle? The maximum span for 2x6 is only about 9 feet.
you won't increase the bounce..
If you add all that weight without adding support you will not have a bouncy floor but rather a big sagging deflection probably.
Reinforcing floor for hearth and stove
So, I will be placing two concrete footings/piers under the load, one in the middle, and one a couple feet beyond out in the room. Beam will be supported on posts on those piers, beam to run diagonally from building corner out to far post to catch each floor joist on a 45 degree angle. I plan to run metal studs on the floor at right angles to floor joists to create a grid to support platform for mortar and stones. Joists are 16 inches on center. Should metal studs be polaced 12 or 16 inches on center?
Why do you want to run the beam out of the corner?
You can run it diagonally from wall to wall, and use the existing wall as support. If you size the beam properly, and the footings under the wall are adequate, it would save having to add additional footings.
If you run it perpendicular to the floor joists, only one post / footing woudl be required.
Why the "studs" laid horizontally? Do you need the hearth raised? Or, are you trying to distribute the loads over the joists?
Reinforcing floor for hearth and stove
I was thinking about the center of mass of the hearth and stove. It makes sense to run it from wall to wall. The stud walls are on a poured concrete foundation wall. I did not think of that configuration saving me from new posts. The purpose of raising the hearth is toinsulate with rock wool and to place the stove on the stones at a position relative to the floor for ease of filling and cleaning and also to view the fire through glass doors. The doors are older and small, glass is only 6x6, so placing the stove at sitting height for viewing is desirable. Height of largest cobblestones is approx. 6 inches, legs of stove are approx. 4 inches tall. A hearth of 10 inches height is workable.
Same
Going back to your comments in more depth, if I run beam from wall to wall it will not be perpendicular to walls, but across the floor joists at 45. Do I need a post in the middle? Running hearth joints perpendicular to floor joists is to support the raised hearth and distribute the loads, as you asked.
Same
My understanding is this, if I run beam diagonally from wall to wall it will cross under the hearth and stove load. I would support the beam on each end on the foundation using the sill as base for a post at the side.
Or, if I run the beam out perpendicular from one wall so that it is perpendicular to the floor joists then a single post can be used at the endpoint of the beam. Are those ideas what you are suggesting?
Which provides the most support for the new load? I like the idea of reducing the need for footings and posts.
Thanks for the help.