newbie rmh question

i quickly scanned the forum, but did not see this question covered, so forgive me if i missed it.

most of the plans and rocket mass heater examples i have seen look like they are in new construction, or garages or shops.
i'm wondering if it's possible to add a rocket mass heater to my existing home?  it was built in 1950, the foundation sits on posts over a small crawlspace, no basement.  the room i'd like the heater in has vintage red oak floors i refinished a few years ago.

my question is, are the rmh in general by nature of construction materials too heavy for this application?  would it just fall right through the floor?
also, what's the permitting process like?  i'm in portland, oregon, where you need to file a permit to take a pee.  

in the center of the house, in the kitchen, there is a vermont castings encore wood stove,  but unfortunately this only heats the kitchen and the second floor. the heat never makes it out to the living room, which is on the north side of the house with three exterior facing walls at east, north, and west.  brrrr.

tia,
christine

edited to add, here's the home layout:

Concrete piers ans floor reinforcement should do the trick.

Hi Christine:  Welcome to permies!  As max said ,adding a few concrete piers under the floor should keep your RMH from crashing thru...if possible setting it across multiple floor joists distributes the weight better than running with the floor joists.   Your beautifully refinished  red oak floor ... will need protecting, You can  raise your RMH over that floor utilizing plain clay bricks laid flat with concrete board laid on top of them, then your RMH is built on that . This will leave a 2"+ air gap underneath allowing air to circulate .  If you are building up against an outside wall that is poorly insulated, consider leaving an air gap or insulating better there as well.  The idea is to keep as much heat in the house as you can.  When building your rmh consider that brick / stone holds heat longer than cob. The all cob masses are beautiful but    in my opinion  encasing your mass with clay brick or stone holds the heat longer and its a LOT less work than making and repairing cob.

Hi Christine:  Your question about permitting is a hot topic. A  lot of people would like rmh to be insurable. I believe that the Wisners succeeded in permitting a rmh in the Portland area (I could be mistaken on that) . Ernie and Erica could tell you if that was so and what hoops they went thru to succeed.  
In my opinion ) Your home already has a wood stove ... is it permitted ? You will have to excuse me for this but I live in rural Montana where there are no permits for much of anything so my thinking is slightly (highly) biased... Who will know your Vermont castings stove is missing and this totally awesome RMH is installed in its place ?  That is not proper main stream society thinking there...   radical off grid recluse thinking from the far reaches of civilization ... But ...
 

Ernie and Erica worked with Portland code officials to get an official permitting process for RMHs: Rocket Mass Heater Permitting

thanks for your replies!  this is good news indeed, i was about to give up hope.

i know absolutely nothing about structural engineering or foundations.  i do know that i have a very tiny crawlspace, and that the center of the house settled about 10 years ago so slopes downward in the middle.  it's been recommended i jack the house up to level it and put in new supports.  sounds like i should combine these projects.  here's a couple shots of the underneath from the home inspection.

gracias,
christine

Your floor looks in good condition aside from needing better support, so I would say you can definitely combine the tasks and jack up and reinforce the structure. It can be a simple enough job that, if you are observant and careful, you can do it yourself. Several 4- or 6-ton bottle jacks won't cost much and should be able to slowly lift the low parts of the central beam so you can slip in new solid concrete blocks in whatever combination is needed to fit. Once you have determined the best location for your RMH, you can add a new beam under the joists centered under the footprint and put in blocks as required. If you are good at figuring things out and making things, you might go it alone, or if you are not confident, asking someone who is good at projects would be wise. Finding out exactly what will be required before starting would be a good idea too.

By the way, supporting the new load will be easier if it runs crosswise to the floor joists so the load is already spread out; you can run it parallel with the joists, but that will need a bit more finagling to get adequate and consistent support. If you want a concentrated load like a tall bell mass, that would probably need the floor cut out and a dedicated foundation built.