Fireplaces in Bale Walls
It is very common for homeowners to want a fireplace these days, and the addition of flames into a straw bale home wall assembly is often a cause for concern to the local building inspector. Most of today's stoves, either direct vent gas units or wood units, are designed to have minimal clearance around them to flammable materials.
In "the old days," a fireplace emitted a lot of heat all the way around the unit and needed to be greatly isolated from the walls or surrounded with a nonflammable protective layer of brick or stone.
Today's units can have as little as a few inches of separation from flammable materials because the majority of the heat is directed forward and/or up, and the sides and back of the units do not get very hot at all. That said, it is still good practice to consider the risks of fire-produced heat being introduced into a bale wall assembly, either at the unit or the stove pipe.
Another thing to consider when installing a fireplace unit in a straw bale home is the difficulty of the installation. For this reason and the reason described above, I install my units into a framed "faux" wall within the bales.
In other words, I frame out a wall that is even with the face of the bales so that once it is covered in drywall and plastered, there will be no difference from the surrounding bale walls. This creates a simple installation for the unit and allows for the addition of a blower or other upgrade in the future.
If the unit is installed directly into the bales, adding such upgrades in the future would be more difficult. The framed wall also creates space for the venting pipe installation and can also be used to create an entertainment shelf or plant shelf above the firebox. The last one we did had a beautiful cabinet above the fireplace, which held a small TV for the master bedroom. The framing makes all of this easier.
-Andrew Morrison