Wall Enclosure: Siding Question

[yopperboy]

FB Pompei Community,

Long-time listener, first-time caller! I'm about to finish the brickwork (one more course of arch entry), and I have a question about the siding.

I will be building a walled enclosure and gabled roof over the dome. I would really like the exterior wall to be cedar shake to match the shed behind the oven. I did some reading on attachment to Hardie board, and while it can be done, it seems like it will require a lot of extra work.

For insulation: I will be doing the FB ceramic blanket with chicken wire and loose-fill insulation.

My question is this: If I install the Hardie board on the interior side of the metal stud wall to hold insulation back and act as a fire barrier, does anybody see an issue with heat/fire concerns about having plywood installed on the exterior side of the studs so I have a good nailing substrate for the cedar shakes?

This has been a long project and the end is finally in site! I have followed the construction manual verbatim to this point, and I have a little anxiety deviating from it. I would really appreciate the community's input.

Kind regards,

Michael

[david s]

Hi Michael,

I’m sure your insulation will be sufficient for heat to not bother the ply, although it is a bit hard because you’ve not documented just how much insulation you have. With the extra loose insulation fill between the enclosure walls and the ove, the heat on the ply should be negligible. Wood only begins to burn above 250C, but can expand and warp at much lower temperatures. Only when the insulation becomes moist will it not work properly and therefore transmit heat by conduction.
It is therefore prudent to do your drying fires to purge the construction oven moisture before adding the loose fill, also because ply does not like a combination of heat and moisture. When filling the enclose the corners take up a lot of extra volume so you can save a fair amount by filling them with empty capped plastic bottles.
i like the job you’ve done on the casting to transition the vent to the flue pipe, nicely thought out.