Tray Raul

A couple of months ago we finally received our 20ft dome kit from pacific domes. We intend to use it as a sort of "outdoor living / family room" and are planning to put it up a couple of months once other projects are complete.

There are a few different options for the floor:

1. Portable “Pie Piece” or “Star” Method
A pie-shaped wooden deck that can be disassembled.

2. Stationary Joist Method
Basically a wooden deck.

3. Perimeter Boards
Wood board perimeter filled with either earthen floor or cement.

We're tentatively planning on #3 and already have 4x4s cut at the proper angles. The plan is also to fill with cement instead of cob, then tile over the cement (we have loads of free/spare tiles and prefer the feel of tile.)

Questions:

Anyone ever done this before? I haven't had much luck finding photos of anyone using the perimeter board method.

Even though I've already got the 4x4's cut, based on the terrain where we're planning to put the dome, we'll either need to bring in some fill dirt and level it out, or ditch the plan altogether and go with #2, if we did so, how feasible would it be to put ceramic tiles over a deck? I guess I could put cement board over the deck?

Thanks!

Just a minor update here. We went with 2 DIY spay foam kits, then put up fiberglass insulation over that (couldn't find rockwool anywhere.) We then used rigid foam boards to insulate under the shed as it was too tight of a fit (and messy) to attempt the spray foam there. The heat is coming soon, and we'll get to see how well it holds up to condensation we've not put up the ceiling yet so still have a chance to peak and feel behind the fiberglass insulation on the ceiling.

As far as smell, I've not noticed any and I'm pretty sensitive to that sort of thing. I think I have some pictures if anyone is interested but it's nothing spectacular IMHO.

Also, for anyone with a beard attempting to do the DIY spray thing yourself, google the "Singh Thattha" technique for wearing a respirator thanks to COVID there have been a lot of research and fit tests showing it's effectiveness.

Thank you all for the helpful replies!

R Scott wrote:At this point, closed cell foam is the best cheapest solution, although not that green. You can do the minimum closed cell and then some rock wool for sound.

That is the strategy that I've been considering and it sounds like that might be the best route.

Douglas Alpenstock wrote:For the roof, I would strongly recommend a "micro-attic" -- a substantial (3-4") air space between the metal roofing and the insulation layer (like Roxul), with lots of vents on both the low side and the high side of the roof.

I've been wondering about this to some degree but haven't considered creating a "micro-attic". Are you suggesting that I don't use the closed cell spray foam on the ceiling at all? When you say "vents on both the low side and the high side of the roof", where would the vents go? On the front above door and the rear? I've attached some additional photos of the outside of the building (before we had it delivered.)

It's worth noting that I've also looked into prodex and reflectix but have heard conflicting information about their efficacy.

I've also considered installing a solar attic fan such as this one: https://www.amazon.com/Solar-Roof-Vent-RVOblaster-Galvanized/dp/B075DVKMR3/ref=sr_1_14?crid=3SRMT7U0CYG7R&keywords=solar+roof+fan&qid=1661738762&sprefix=solar+roof+fan%2Caps%2C176&sr=8-14

But the thought of cutting into the roof is rather unnerving especially since the roof is ridged and looks like a pain to get installed properly but I think it would do wonders for air circulation.

Pete Arthur wrote:Yes, you need insulation.....

There is no alternative.

Spray foam will give great service for that "NEEDED" layer to your structure, but will be $$$$.

If you go get 3/4  or 1" foam board, (whatever the thickness of your purlin lumber), cut it to fit inside the rafters, AND caulk all the edges and seams,
you will pay $.

It would be easier to unscrew the metal, install foam sheets in full size (no cutting), re-install the metal (that already fits),
with longer screws to account for the thickness change due to insulation, and call it a day.
You should metal tape the seams of the foam as you install it. Foam Shiny side down. Tape on the living in side
You will not have a moisture drip problem.

I'm glad that you mentioned the option of unscrewing the metal. I considered it but really prefer to not take the walls off, I also don't have much of a roof overhang and have already installed gutters which might get in the way.

We're building a tiny off-grid camp in the Southern US (USDA hardiness zone 8b) where it's extremely hot and humid.
We have a metal building with a wood frame and I'm very concerned about condensation and mold.

To combat that concern we're taking the following steps:

We have painted the interior wood frame with a mold resistant primer.

We'll be using a wood burning heater in the winter (likely not much as winters are mild here.)

No cooking or propane usage inside.

There is no bathroom, kitchen, or cooking inside, we're going to create separate structures for these in the future.

We have our solar and electrical wiring tested and nearly complete and very soon we're going to install insulation.
All the information I have found regarding our climate suggests that if we use insulation such as fiberglass or rockwool we should have a vapor barrier on the outside of the structure, this is not possible for us as the walls are already on the frame and have no vapor barrier (see attached photos.)

Another option I've found is to use closed cell spray-in insulation which is both a vapor barrier and insulation and is a good defense against condensation. Some of the shipping container builds I've seen have gone this route as well.

I have a few concerns with the closed cell spray foam insulation but I have more concerns with condensation and mold so will go that route if it's best. I just wanted to ask the community here if there were any other options. For example, would I be able to use some kind of paint or roll-on vapor barrier on the metal interior then use rockwool for the insulation instead of spray foam?

Thanks!