Porta-Home Construction, Part 2: The Difficult Matter of Insulation

February 17, 2017


"To insulate is to thrive."


The above is a quote I just made up but am surprised doesn't exist, for spending but a short bathroom break in the PolyJohn We'll Care III in the sweltering California summer is evidence enough of the challenges of working with a plastic structure. This porta potty gets hot. Real hot.


Insulating it was never an option. It was a necessity


Just how we were going to insulate it was another question entirely. 


We knew the structure would be shaded by a second-story rooftop garden, relieving the home from the worst of summer's searing singe. We also figured a window and open door could provide a cross-breeze to ventilate in the most dire circumstances. And we have discussed various ways to further ventilate the home with solar fans and, if necessary, a micro-a/c unit. 


Insulation would be the keystone link between the above solutions, ensuring hot air stayed out and whatever cool air we could invite in wouldn't have such an easy time leaving. And, in winter, vice-versa. 


The challenge was determining what kind of insulation to choose. Without attempting to educate my novice readers (or alienate the experts) with evidence I myself am just learning, I will say that we settled on polystyrene foam board panels as our main source of insulation. Compromising between a thick barrier and maximizing interior space, we went with 1.5" panels. 


Because the walls of the porta potty are aggravatingly contoured, we accepted having to insulate shallower sections of wall with thinner panels. And because Home Depot ran out of thinner panels--and we were too rushed to wait for a re-stock--we decided to shave the panels for those shallower sections. 


Each contour required its own strip of paneling. Which is as time-intensive as any element of the construction in Phase I. 


This may seem like an inefficient method. And it was. But once the panels were glued to the walls it was apparent that our secondary reasoning for using panels over fibrous rolls was working wonderfully--the paneled insulation was reinforcing the walls, making once-flimsy walls sturdy. 


Supplementing the panels was spray insulation, tightening up gaps and crannies, as well as a thin sheet for the floor and a fiber roll for the baseboards. No more stray spots for drafts.


Geno puts the finishing touches on the baseboard insulation before installing the floor sheets below--a thankless task.


Before moving on to framing the interior, we conceded that the ceiling and door would have to wait for their insulation. Phase I of construction would leave them bare, banking on "intermission" of the build phase inviting press cameras out to view the progress and knowing a more diaphanous top and factory door would appeal more to the camera. 


Sometimes even charity efforts are best pursued with the media in mind...


We won't know if our decisions were the best decisions until the prototype is road-tested. But for now, we think the extra work put into insulating the unit properly was the right idea. 


Let's see how I feel about that come summertime...




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Los Angeles, CA 90064

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