First off as an insulator of 10 years I must say you did a wonderful job. I know how anyoing it is to work with roxul, it's awful. Your batts are very nice clean cut, friction fitted to your studs.
What mil poly did you use ? 6ml ?
Your Polly job is nice as well, I like how you taped the windows and doors to on top of the acustical .
A thing you can keep in mind for next time is to do the caulk behind the Polly boots of your outlets, so to seal it because the tape drys and is known to separate after a period of time; It's code to do that In All houses in kamloops now.
Also you said your ceiling was like a wall did you make sure to put vents (baffles)in the ceiling all the way through on every run?
Thanks, glad to hear I at least did a decent job. I didn't know about the acoustical around the poly boots but it makes sense.
There are no vents of any kind in the roof/ceiling. It receives no air flow by design. There is no soffit or overhangs on the tiny house due to width considerations.
With not having vents it can cause condensation and if you live in Canada like myself you can get a problem with snow melting off the roof and causing ice. It's the air space that helps prevent that, as in normal sized houses your attic space is roughly the same temp as outside give or take.
That's not to take away from the amazing job you have done, and that shouldn't cause to much problems, as you don't have a foundation to divert water away from. It would be the condensation in the ceiling I would keep an eye out for in winter time .
We have actually been through one winter already. When I was building the house I didn't have time to blog about it too so I just took pictures and video with the intention of blogging when I had the time. So far no issues with condensation on or in the ceiling. The key is that I sealed it to the point of having no airflow both on the inside and the outside. No airflow means that no moist air is entering the ceiling to condensate.
I am a roofing service tech and deal with condensation related issues in attics a lot during winter so that is how I came up with the idea. Another way to look at it is that it is acting more like a flat roof then a conventional roof system. I think the biggest draw back to this system would be that the shingles probably get hotter without the airflow from below and will probably not last as long.