Roof insulation for the OKC container home

Apologies for the delay in progress updates for the OKC container home. I have been reluctant to post about what has been, to date, the worst aspect of construction, mainly in terms of execution and results.

After searching for a residential spray-foam contractor for several months and then waiting for the weather to cooperate, I finally found a guy who was both interested in the project as a whole and also seemed competent, SEEMED being the operative word. We had to wait for the weather to reach a suitable threshold so that the foam could cure properly, and that itself was a wait of one month, and then waiting for scheduling availability created another month’s delay.

Finally, dude showed up to do the work. (I’ve decided to omit the contractor’s name because, in fairness, he was trying something new and untested in light of the uniqueness of my project; however, if you would like to avoid hiring him, message me directly or comment and I will give you his name.)

We had originally discussed and agreed to him spraying two inches of closed-cell foam on the roof’s exterior. Then, Morgan and I would coat the foam ourselves using a product based on his recommendation (more bed liner, most likely). He had told me he would build a scaffolding around the roof so as to block the wind and also trap any errant foam during application.

Sounded like a plan.

When dude showed up, however, he springs on me the idea that he can avoid building a scaffolding by instead building a wooden frame around the roof perimeter and then laying plywood panel across it, under which the foam could be sprayed. Further, the plywood panels would have plastic sheeting on them to which the foam would not stick. That way, the panels could be removed, and Morgan and I could proceed with a protective coating as planned.

BUT THEN, dude suggests that if he were to omit the sheeting and just allow the foam to adhere to the panels, I would have a rooftop surface on which I could walk and potentially develop a patio. The only caveat was that he couldn’t guarantee how level the plywood surface would be given unpredictable expansion of the foam between it and the roof.

After some discussion in the driveway, I eventually went with this latter plan, as the idea of a walkable rooftop appealed to me.
I should’ve stuck with the original plan, though, and not let dude off the hook from what he originally told me, because the results were far below expectations and in fact constitute the most embarrassing/lackluster aspect of the container to date.

container roof foam
To install spray foam insulation on the container’s roof, a 2×4 frame was laid around the container’s upper frame.
spray foam container roof
Sections of 4×8 sheets of plywood were laid across the 2×4 frame and screwed together.
container roof spray foam
Closed-cell foam was then sprayed underneath the plywood sections, thereby adhering the wood to the container roof via the foam.
spray foam container roof
The end result left a lot to be desired. First, each plywood she had been installed upside down, with a big black stamp reading THIS SIDE DOWN facing up. it’s hard to see in the picture, but a regular expansion of the spray foam in each plywood sheet had caused peaks and valleys between each section of plywood. Some sections had way too much foam under them; others, not near enough (if any at all).
seam between plywood panels
This shot typifies the seams between plywood panels across the roof. Morgan and I would eventually shave these down to create a smooth, sloping seam, and then cover them all with generous amounts of caulk.
container roof spray foam
When I asked the spray foam guy to come back and add more foam to sections of plywood that seemed like they had more give than others, I would find several holes that appeared to have no extra foam sprayed in them at all. You can see how this hole, drilled after the installation, lacks excess foam flowing out of it, as had been the case with every other seam between plywood sheets.
foam seams
Work begins on smoothing out the foam seams between panels.
container roof structure
Morgan wound up having to make cuts to the edge of the plywood/2×4 roof structure. I had originally asked dude to do it; he tried, gave up and called another guy. That guy did a terrible job, so this is Morgan setting about fixing it.

Eventually, all the roof work was completed. Having the insulation on the roof made an immediate difference in the climate control inside, and now, if I’m heating the space, the thermostat will usually crawl one or two degrees above the set temperature AFTER it kicks off. It also stays cool for a long time if I need AC, and it only kicks on a couple times per night (that I’ve noticed).

So, despite the headaches of dealing with yet another sketchy contractor, addition of insulation has made a positive improvement to the container’s efficiency.

Just try not to scrutinize it too closely when you come to visit.