Author Message
Gilbert Fritz
Post     Subject: Could an insulated foundation BE the thermal mass for a Rocket?

I will be starting a new thread on my greenhouse project very soon, which will have lots more information.

Currently looking for a replacement for a concrete bond beam, but have not found one yet.
allen lumley
Post     Subject: Could an insulated foundation BE the thermal mass for a Rocket?

Gilbert : Jay C. White Cloud has raised some good points, all of the concrete used should be insulated, as the only good that using block bond
walls is in its Total mass! As the solar inspired shape of your green house will shed sheets of water at the Foundations base ample drains
pitched away from the Foundation and running to daylight or a drywall are common site needs, primary attention should be made to make
sure the the outside of the foundations Perimeter is landscaped to lead all surface waters away from the greenhouses base!

There were a few questions about size,shape and orientation of your G'house, Again several 55 gallon drums filled with water can be very
effective early in your growing season as additional Thermal Mass and can be placed to Temper and break up the flow of cold air every time
your outside door is opened early in your growing Season

All the concrete used will be hydrophilic and actually hold water locked within its structure, and promote wicking to the inside sub-soils and

There is a widespread acceptance of ample watering within the structure of the Greenhouse and generally for that reason (and others) the
use of a ground vapor barrier is contra indicated without some type of drainage field within the green house leading to a sump and pump!

These are important additional considerations while planning your build, nothing printed here changes my recommendations earlier, in the
final analysis the final decisions are yours ! For the Good of the Crafts ! Big AL !
Jay C. White Cloud
Post     Subject: Could an insulated foundation BE the thermal mass for a Rocket?

Allen...this is all yours Brother...I can not keep up with all this use of "concrete" when not needed...

Concrete should be a medium of "last resort," if anyone is trying to work within the parameters of natural building or permaculture. Recycled "urbanite" and the like I am all for, geopolymers and limecrete yes!! OPC...not at all, as the industry behind it just does not support the "lowering of carbon footprints" that we should all be trying to support...
allen lumley
Post     Subject: Could an insulated foundation BE the thermal mass for a Rocket?

Gilbert Fritz : Location, location, location, Heres a pitch to go to he Permies toolbox and click on the [MY PROFILE] tab, and then enter as much of your
personal data as you feel comfort able with ,look at your name space, and L@@K at mine, this is a good way to find a Fellow member with Rocket, Greenhouse,
and Cob experience who is a Near Neighbor! This also lets everyone know if they can comment relative to your local weather!

So- location, climate, (humidity) size of greenhouse, orientation and construction, connected to house, how many months would you like to extend your season
by, any specialty uses or thoughts of commercial usage?

Think about this while we talk about the two most common sizes , A 6'' Rocket Mass heater RMH will let you flow your hot exhaust gases 30 feet before finishing
with a final vertical chimney, thats 30'- 5' for every elbow, so a straight run with one elbow 25 ' plus the footprint of your RMHs footprint !

The 8'' system can flow the hot exhaust gases 50'-5' for every elbow before your final vertical chimney , a little more to play with !

I have a personal preference of having the whole thing built as a tall thermal bench that can be made into a seed starter bed or a raised bed well above the cold
outside air that will fall into your G'house every time you open a door in winter, and besides the tall raised bed will be a LOT easier on your Back, Your back will
thank you every day, just placing the horizontal pipe low in your mass will guarantee that the floor of Your G'house is coupled with the thermal mass !

Also if you have an arctic clipper come visit you if your thermal mass runs down the center it will be the top point of twin row covers you add to hold a little heat
in the air because the ground and the plants are already warm!

Burying the pipe in the ground means you need to protect the pipe from collapsing when someone walks on it and ground moisture is a greater problem ! Also
there will be a higher loss of heat at the perimeter if you snake your pipe around the outside walls !

As a side not, at the beginning of your growing season before all your space is filled with plants additional 55 gal drums filled with water will greatly increase your
thermal mass !

In the end how you build it will be your final choice ! Good luck. For the Good of the Craft ! Big AL
Gilbert Fritz
Post     Subject: Could an insulated foundation BE the thermal mass for a Rocket?

I am building a greenhouse with a rubble trench foundation. This is a two foot wide trench filled with crushed concrete, lined on the outside with polystyrene insulation. It will be capped with a concrete bond beam. If I ran the stove pipe around the foundation, would this be a good way to stack functions? I could also use a trench full of crushed concrete as a rocket mass and as a path, but somehow the foundation idea just seems interesting.