Brian, Could you help answer a DIY question?


You, or anyone else who is more up on the unvented roof technologies, could you possibly do me a favor on a site called forum, which is the home owner sister site to where I help moderate on both forums.

A home owner has a question about an unvented roof with a pool inside, which is in the preliminary build stages right now.

I know we tend to disagree about ventilation necessity, but on this particular design, I do not have the necessary experience to more than adequately answer this posters questions.

The link to the thread on that forum is:



I’ll probably get around to it in the morning, Ed. Almost midnight here. G’night!!

Thank you. I appreciate the help.


Tried last night to get on the site but had problems. Could be that I may have registered about a year ago. Remember making a post or two on a site you were connected to through your blog…could it have been the DIY site?

Will try again tonight.

Brian and others who are familiar with this insulation method, I just recieved a new post from the DIY’er with the original questions.

He now has changed course, taking your suggestions, but still may need clarification on the thermal bridging aspect.

His reply is copy/pasted below.

Thanks again,


Thank you, Ed!

My appologies for only just now following up on this.

I’m not sure if the BCI (wood I-joist) will create a thermal bridge, but our current plan is to use closed-cell spray foam insulation (as opposed to our plan a month ago to use damp-spray cellulose), for the waterproofing qualities Brian points out. Updated description of roof construction accordingly:

ice shield
vapor barrier
radiant barrier
14" BCIs filled in with closed-cell spray foam insulation
TnG pine

I have the framing plan, but its just a bunch of I-joists. The structure is 2 volumes:
1 volume is the pool room, pool systems room, and airlock entry
2nd volume is typical living spaces
They are separated by a 2x6 framed wall topped by a clerestory.
This creates 2 opposing shed roofs with the high point of the small volume 4’ lower than that of the large volume (with a short window wall filling in the gap).

Maybe this cross-section helps. The small (left) side is the pool room.
Attached Thumbnails](“”)