White Metal Roof with Rigid Insulation

Created on June 24, 2011 using FlipShare.

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[uva3rdgen]

Did you say that they coated the metal roofing in KYNAR? Holy top of the line batman!

Three questions:

How did the coating hold up when walking on it?

How slick was the KYNAR coating?

Can you show us how the gutters were hung?

[MattRisinger]

@uva3rdgen Yes it's a Kynar 500 factory painted roof. That Kynar coating has a very good reputation for longevity. The coating holds perfectly under foot traffic, and is slightly slick but holds well under foot when dry. I'll shoot a future video and show you the gutters and rainwater catchment system. Thanks, Matt

[Rockytxv]

Great presentation. Will be very little heat gain or loss through this roof. What kind of support do you recommend under the polyiso foam boards? Is the roof area too hot for using extruded polystyrene in place of polyiso boards?

[MattRisinger]

@Rockytxv The support under the ISO is full 1/2" roof plywood. I would think you could use Extruded Polystyrene as well, that would be less expensive. It will get hot under that roof even with the 3/4" lath, I would expect the top of the foam to be upwards of 120 degrees on a hot July day. -Matt

[johnnymac1976]

I'm building a mobile tiny house in San Antonio that will move to a temp zone 4 with lots of snow at some point.  In my case would it be better to put the ice and water shield directly on the OSB decking, then install the foam?

[MattRisinger]

@johnnymac1976 Interesting project! I think you could go either way, the benefit of the ice/water shield on top that any water that does get by the metal roof goes on top of the ice/water shield and is directed off the roof. If you ran it under the foam you might tend to trap more water long term. It's probably ok either way though. Matt

[bobmcalister]

excellent presentation and step by step . I love Austin ...6th street?...anyway , leaving the airspace between the lath and the metal should actually decrease the probablility of condensation from my experience. Airflow is the name of the game and you have that. You may want to contact Tremco and see if they still have a program for estimating condensation problems before construction. good job on the video ! did you use a flip?

1

[MattRisinger]

@Bigrignohio Yes, I think Open Cell foam is the way to go for our Hot/Humid climate zone. It could in theory dry to the inside but the idea of the full peal/seal is that you'll have little chance for a leak. It's certainly not as forgiving an old school vented roof but this certainly will be VERY efficient. -Matt

[Bigrignohio]

Very nice work. I would not have thought of using a herringbone or slanting layout like this. Solves the issue of locating the lath directly under the roof panel seams. You mentioned using 6.5" of spray foam under the roof. Is this open-cell foam to allow drying to the inside? With a under 0.1 perm peel-n-stick there would not be any exterior drying. I know this is a low risk with the waterproofing used but still possible, especially once the owner takes possession (satellite dish, etc.).

[MattRisinger]

@boardman4ever101 True we do have more penetrations, but that's the reason for the Water & Ice protection membrane. It's a self sealing product that should last the length of the metal roofs life. The 3/4" air space gives any water that gets into that space the ability to dry or drain. This really is a best practice method for roofing in this climate zone. Matt Risinger