Correcting my roofing problems

I have another question for you roofers out there. The roofers that are working said that they want to put insulation on top of the existing roof the just installed.

The roof is a modified roof that is already existing. They want to put insulation on top of the granulated.

My concerns are as follows:

  1. The mater of adhesion with the winds of 150 mph hurricanes

  2. The roof is a precast concrete roof. I am concerned that there will be premature roof failure at the joints as the concrete expands and contracts. Without the insulation there will be no ability for the roof to move separately from the deck.

  3. That the 2 separate layers of modified roofing will act as a vapor barrier trapping condensation in the layer of insulation. Causing the insulation to deteriorate over time.

Any comments or opinions that any has on these matters would be greatly appreciated.

Thank you,

all the roof over concreate decks i have had the pleaser of replacin have
all had insulation in between the deck and roof.
just the way it is.


Bet Aaron B. can answer this one to a T. This is right up his alley.


I know that in your standard application that the insulation goes between the deck and the roof, but do you know if doing otherwise will be detrimental?

by the way Gweedo, thanks for your responses

I’m not a roofer (at least not anymore), I’m not Aaron B., nor am I gweedo, in fact I didn’t even stay at a Holiday Inn last night, but here are my thoughts anyway:

  1. Yes, you can install insulation overtop of a roof system in what is known as an IRMA configuration. That is, basically installing the roof membrane overtop the concrete roof deck, then installing an extruded polystyrene insulation that is generally covered with a filter fabric and ballast (stone or pavers). Now, in your case the local building codes may not allow you to use an IRMA roof, because if the contractor decides to use river rock as the ballast, the rock becomes projectiles during hurricanes if you start to lose the roof.

  2. If they are talking about installing insulation, and then putting more roof membrane on top of the insulation, thus sandwiching the insulation, I would not recommend it. There are a few problems with doing the roof that way. First, you may invite moisture problems within the system with regard to condensation and dew points. Secondly, if the top roof membrane ever leaks you would likely not know about it until the underlying roof membrane started to leak. You could end up with a lake trapped between the two roof membranes, thus increasing the dead-load weight on the roof, and the wet insulation would lose its R-value.

What exactly is it the contractor is wanting to do??? And out of curiosity, I assume this is in response to you calling him out on not meeting code, and the higher energy bills you will encounter with the new roof system. Is the HOA involved, or are you going at him yourself?

That is some whack advice yo.

Double roofs are installed all the time, not only how I mentioned in the other thread, but also, more in this configuration in the way of mopped down vapor barriers (and we all know the difference between vapor barriers and vapor retarders).

You surely wouldnt create a break in the VB to direct a leak that shouldn’t be there to a penetration (remedial sloutions), would you? Now we are building the roofs to accommodate jack roofers? Would you assume that there would have to be a pond for some reason?

I would say give yourself double the protection, Mr. Homeowner, and go ahead with the new insulation and membrane. There should not be condensation issues if they have properly installed the roofing systems. You insulation will also likely be a closed cell insulation, so dont worry about it breaking down if it were to get wet.

i just dont think ya got much choice rite now.
ya gotta have the insulation.
your stuck with roofin company.
just have em putt it together.
try to get some kind of unconditional 10 yr warrsanty.
and worry bout trouble later.
ya need insulation.

good luck


I am on the HOA and am the only one who knows anything about construction. I joined the HOA after the problem was found.

Basically the roofers messed up. This is there pitch to try and save themselves. If we accept this, it will relieve them of a lot of there accountability.

Anyways they are fully responsible for this. We might have to sue them to get the proper roof.

On Friday I spoke with a local roof consultant who was recomended from several contractors i trust. He confirmed several things I was afraid of:

  1. That adhereing insulation to a modified granulated when a wind speed minimum of 150mph is not recomended.

  2. That he was concerned about the membranes acting as a vapor barrier in south florida. Roof temps can easily exceed 130F on an average summer day and there is usually a humidity level of over 90%.

  3. My roof is a precast roof with double Ts. With the roof applied directly to the concrete and with expansion and contraction at the joints, he was also concerned about premature failure at the joints.


Your consultant sounds like he is a good guy and knows what he is talking about for your area. I will say this, with regard to wind-uplift and loss prevention, the consultant needs to make calculations based on building height, parapet height, ground roughness, location, etc. to determine whether applying the insulation over the granule-surfaced membrane will work. He is right, however, it is not the best surface to bond your insulation to.

There are a couple of things you can do though to help, the roofer can “heat prime” the roof surface and sink the granules into the roof membrane. Then it would provide a better surface for mopping insulation down to the first roof with asphalt. You could also look into Insta-Stik, though I don’t know if it will meet your wind-uplift requirements. Ask your consultant, he will know what is best in your area.