RMH in a Pier and Beam House??

We started the long, slow, DIY house design and building process months before I found permies.com.  We are doing pier and beam construction and are 1 footing away from starting to go up instead of digging down.  The front of our roundwood timber frame and cordwood home will be a large open space housing the kitchen, dining, and living areas.  I really would like to put a RMH between the dining and living rooms.  All the construction I have seen on RMH's is on a concrete slab.  Oops, we are building a pier and beam house!

In order to include a RMH in our build, I've thought of the following options:

1 - put in extra 8" or 10" piers on 2 or 4 foot centers under the area for the RMH and use cement board on top of the sub floor in that area.

2 - build a concrete foundation under the area for the RMH and tie the surrounding floor joists into it.

Any thoughts or ideas to help this be a success are appreciated.  And, if I'm all wet and my efforts are doomed for failure, I'd appreciate knowing that as well before I waste a lot of time and money.  My gut tells me that this is doable, it just has to be properly designed and engineered.

I would guess either approach would work. The important part in either case (piers or concrete footer) is that you have some insulation between the core and the mass of the RMH and the supporting structure. Lots of heat will radiate down from here and you don't want it either 1) weakening the structure, 2) creating a fire hazard, or 3) getting wasted heating up things below the living space.

Phil Stevens wrote:I would guess either approach would work. The important part in either case (piers or concrete footer) is that you have some insulation between the core and the mass of the RMH and the supporting structure. Lots of heat will radiate down from here and you don't want it either 1) weakening the structure, 2) creating a fire hazard, or 3) getting wasted heating up things below the living space.

That's why I'm wondering if putting in a concrete slab foundation under the area for the RMH would be prudent.  The foundation walls would be approximately 2' at the "short" end and 2'8" at the "tall" end (above grade measurements, I'd have to go down about 2' as well).  I'd have to fill inside, then put a slab on top of the fill.  Either way, I'm figuring I would have to put a layer of fire brick and kaowool under the RMH to isolate and insulate.  I've watched some of the videos about bell type RMH and think the reduced weight would be to my advantage in a pier and beam structure.

Yes, a concrete foundation under the reduced weight of a masonry bell should provide adequate support. The layer of firebrick and kaowool should give you the thermal break required. Are you in a seismic risk zone? Think about how the masonry structure is tied to the foundation, or whether you want it decoupled.

As long as the piers have adequate spread footings, putting those in as described would support an RMH mass. Running the floor framing continuously across the whole floor, with just the added support of extra piers, would increase the stability of the whole system. You would then just use an air space and some insulation like perlite-clay under the core and mass to keep the floor from getting too hot (and incidentally from losing heat to the outside).

If you have soils that might settle unevenly, or are in a seismic risk zone, the continuous foundation would be safer.

Glenn Herbert wrote:As long as the piers have adequate spread footings, putting those in as described would support an RMH mass. Running the floor framing continuously across the whole floor, with just the added support of extra piers, would increase the stability of the whole system. You would then just use an air space and some insulation like perlite-clay under the core and mass to keep the floor from getting too hot (and incidentally from losing heat to the outside).

If you have soils that might settle unevenly, or are in a seismic risk zone, the continuous foundation would be safer.

Ever hear of the New Madrid Fault?  I'm 68.1 miles from the epicenter of the New Madrid Seismic Zone.  It amazes me how little attention is paid to that when people build in this area.

Okay then, it's a solid foundation for you!

I would like to built my rmh in the basement but I only have 6 feet 3 inches height. I was wondering since the rmh with the baril is 55 inches height is it possible. Can I protect the sealing from the heat of the barel?

Bob Gallamore wrote:I really would like to put a RMH between the dining and living rooms.  All the construction I have seen on RMH's is on a concrete slab.  Oops, we are building a pier and beam house!.

Mr. Gallamore,

Please continue posting if you solve this problem.  I am also on posts; the builder laid the floor joists flat.  I am considering somehow pouring a 4'x9' slab to at least support a RMH.  I have the Wisner's Cabin: 8" Diameter plans and that build weighs approximately 5,400 pounds.

Do you get frost heaves where you are at?

Nikki halverson wrote:

Bob Gallamore wrote:I really would like to put a RMH between the dining and living rooms.  All the construction I have seen on RMH's is on a concrete slab.  Oops, we are building a pier and beam house!.

Mr. Gallamore,

Please continue posting if you solve this problem.  I am also on posts; the builder laid the floor joists flat.  I am considering somehow pouring a 4'x9' slab to at least support a RMH.  I have the Wisner's Cabin: 8" Diameter plans and that build weighs approximately 5,400 pounds.

Do you get frost heaves where you are at?

It doesn't get cold enough for long enough to get frost heaves here.  I'm not sure what you mean by the builder laying the floor joists flat.  We are going to use engineered joists rather than dimensional lumber joists.  I'm planning on putting in additional footings, piers, and support under the area where the RMH will eventually be installed.  Rather than using a U-shaped flue with material packed around the flue, I'm planning on building a bell type heater.  It will be much lighter, therefore easier to support, than the curved flue type heater.  Several posts on Permies about bell type RMH.