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metal cold roof question .....

15K views 30 replies 9 participants last post by  theroofinggod 
#1 ·
On one of my remodel job the client just had to have a metal roof and hired his own metal roof contractor.

I only do shingle roofs, no metal. Here is my question for you metal roof installers. When I install a cold roof I create a real open air space atop of the decking, underneath the shingles. No insulation in that space as it would negate the whole cold roof concept as it is my understanding.

This metal roofing contractor is running 2x4 sleepers over the existing shingle roof, then he installs rigid insulation in the space between the 2x4s (I assumefor rigidity of the flimsy metal panels he uses).

With insulation in the space between the metal and the "decking", is this still considered a cold roof?

Thanks ........
 
#2 ·
The term "cold roof" isn't something I am familiar with, being in Oklahoma, but the practice you are describing is acceptable. You stated the roof panels are "flimsy"?

I guess I need to get up to speed on cold roofing from the northerners, but it sounds like you really don't like metal roofing.
 
#5 ·
I don't mind metal roofs at all .... it's just that I don't do them. My main issue is that it was sold as a cold roof, when in fact - at least in my opinion - the insulation makes it a regular roof construction. Or am I wrong here?

By the way ... in the European Alps cold roofs are making a huge comeback. Rake boards of over 2 feet are not uncommon.
 
#3 · (Edited)
I haven't heard that term in quite a few years but I haven't worked in the mountains in a while either.


copied:
Cold Roof Ventilation & Ice Damming
In central Colorado and other mountainous regions, ice damming is an epidemic problem that results in not only damage to the interior and exterior of structures, but is a safety issue that can be life-threatening for pedestrian and vehicular traffic. To effectively combat ice damming, multiple design and construction factors must be considered and implemented to prevent this phenomenon from occurring.
Ice damming is the result of snow or ice that melts at upper roof sections and re-freezes when it flows to the cold eave sections. While there are several different approaches to reducing or eliminating ice
InfraMation 2003 ITC 092 A 2003-08-15
damming altogether, the approach that has proven to be the most effective through our studies has been the cold roof design. A cold roof is designed to provide a uniform and consistent cross-flow ventilation path from the eave to the ridge of a roof resulting in a more uniform temperature equilibrium across the roof’s sheathed surface. By maintaining a roof temperature of the closer to equilibrium to the outside ambient air temperature, ice damming is significantly reduced because the eave surfaces are now in equilibrium with the up slope roof surfaces (no hot spots). Another roof design concept for mountainous regions to control ice damming is that of the super-insulated roofing system. In theory such a system will work effectively; however the incorporation of 100% vapor barriers at the ceiling level, control of ceiling penetrations such as chimneys, and recessed can lights must be eliminated or designed and detailed properly in order for the system to achieve the desired performance. Solar gain must be considered in both designs, as it may circumvent any roof system.
 
#6 ·
If the metal panels are on EPS insulation, I would venture to say they will not pick up any heat from the attic, and be as cold as the outside temps...so I guess it would qualify as a cold roof. One of the benifits of Oklahoma is never having to deal with those issues. However, I noticed last week traveling through New Mexico, most of the new construction is going metal.
 
#8 ·
if the air space is above awell insulated heated area where no heat escapes to the bottom of the decking ,it`s technically a cold roof application,where there air temp above and below the roofsheathing are similar and don`t attract condensation as the dew point is at the lower insulated ceiling area
 
#10 ·
That's exactly what I am talking about. That is what I construct when I build a cold roof. To me there has to be a completely open, ventilated airspace between the attic decking and the shingle decking of at least 3" or so. Anything less just wouldn't do - in my opinion.

With a metal roof who really cares. There just won't be any ice damming or leaks anyway. I am just talking about the principle of selling a cold roof when it is not.

Thanks .........
 
#22 ·
Thank you god ... I know you did.

However, in the confines of my very specific topic and the snowy cold weather of my region, a "Cold Roof" is a very specific construction technique (double decking, etc), not just a roof that is cold on underside of the final finish material, whatever that might be: shingles. shakes. tiles, etc. Again, I am talking only about cold and snow because I'm not in Florida.

It is recognized by all trades associations as such. Just to mention one is the "Cold Roof Manual" by NTRMA and WSRCA. Here is a section:


My original question was very specific and simple: is the initially described metal roof installation a "Cold Roof" or not.
 
#29 ·
You will, indeed, find a \national standard on cold roof assemblies vs. warm roof assemblies.

A cold roof assembly is a roof that has the roofing/waterproofing not in contact with the insulation (most shingle roofing is cold roofing, but not cool roofing)

A warm roof assembly is a roof assembly which has the insulation in direct contact with the roof deck, with no ventilated air space between the insulation and the roof deck. Am I making sense? Most commercial steel bar joist and corrugated deck with insulation atop are warm roofs.

Ed?
 
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