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The Dreaded Flat Roof

| Posted in General Discussion on April 21, 1999 04:08am

*
My home is one story and has an old tar and gravel roof – actually two of them, one on top of the other (2 layers). Both layers are failing and its time to tear off and start over.

b THE PROBLEM GETS COMPLICATED

My home was built in 1954, and air conditioning was added in the 70’s. Two package type units and metal ductwork was placed on 4×4 sleepers on top of the roof. Although originally passed, the work no longer meets the building code. Since the A/C system has to come off for the roof tear-off, it has to be brought up to code when it is re-installed. Code requires that the package units be placed on stands 16″ tall and the duct work be raised also. Doing this would expose all the mechanicals to the street and look like hell! Once more, my home is in a historic district and the planning commission would surely object to this visual eyesore.

b MY BEST SOLUTION

There is an exception in the building code that would allow me to put the system back on sleepers, but that means that if I had any future roof problems, I’d have to remove the system all over again.

My solution is to build a structure just large enough to house new soft duct work. I figure the finished dimentions would be about 18″ x 18″ x the distance to each vent in the system. Once built, my roofer could roll his roofing material right over the structure. Of course the package units would still be exposed, but they are easy to disconnect and move if necessary.

Anyone see any problems with this solution or have any other suggestions?

Cost is an issue. Current quotes are $8,500 for the re-roof, and $6,000 to replace the existing ductwork with new metal ductwork and bring it up to code. I figure that building my structure and using soft duct work would cost far less than $6,000.

By the way, duct work concealed in interior soffits is not an option.

Thanks

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Replies

  1. Guest_ | Mar 31, 1999 09:56pm | #1

    *
    Thomas,

    I see several possible solutions.

    Building the platform directly on top, in the same location, is one. However, construction would be s follows, build up 8", install a 4x4 cant strip around the perimeter of the raised platform. This allows the roofing felt to come up the sides and be tarred in place. On top, I would install a sheet metal cover, it would overlap down over the edge to protect the seams. Once the unit and ductwork is back on, you can build any kind of enclosures you want and it can be removed at will.

    This would allow for any removals in the future of the unit itself and any repairs would be made easier as a result.

    The next solution is one of practical vs. history.

    Install a truss roof over your existing structure and eliminate the dreaded flat roof forever. It would probably pay for itself in the long run. However, historical societies are dificult to deal with when it's not their property that's suffering.

    Hope this helps.

    1. Guest_ | Apr 01, 1999 01:11am | #2

      *Thomas,I question weather your a/c really needs to be removed from the roof to install a new roof.Comercial roofs are done this way all the time without removing mechanicals.Disconecting or jacking,but maybe not removing.a matter of semantics could save you a ton of dough.I admidt it will be tougher on your roofer but then maybe another local contractor has another solution than the one your present guy wants. Explore all the options.Good Luck,Stephen

  2. Thomas_Haas | Apr 01, 1999 06:04pm | #3

    *
    Gabe,

    Thanks for the reply. Your first solution has been described to me before as a metal curb. Others have suggested that a curb be used under the package a/c units only. Using a curb under the entire system does make sense, but would add to the costs I'm facing.

    Also, I neglected to mention that I live close to the ocean in South Florida. This environment takes quite a toll on exposed metal - galvanized or not.

    Your second suggestion makes the most sense. It would solve all my problems. I've explored this option and estimated a new roof, trusses and all at $40,000 - $50,000. In addition I'd have to replace the package a/c units with split systems. More efficient to run, but even more cost.

    Thanks again for your great ideas. They are definately making me think a lot harder about this project.

    Thomas

    1. Thomas_Haas | Apr 01, 1999 06:14pm | #4

      *Stephen,I agree with you. Maybe I need look harder for a roofer that would be willing to work around the mechanicals instead of removing them. The inspector's, however are another problem. I've had them out and they have a real problem with the existing system. Maybe if I get them on a good day, they will let me replace the roof alone. I just have to figure when that good day will be.Thanks for your reply.Thomas

      1. src | Apr 21, 1999 08:44am | #5

        *Thomas, I worked for 4 years for a large union roofing contractor doing work at pulp mills, shopping malls etc, and we just lifted the units with a big crane, stripped them in( rooofing term to go around curbs) and dropped them back down. The key to this is to have the sheetmetal or HVAC guys there when you do it. Most large roofing contractors have tin bashers working for them anyway.

        1. src | Apr 21, 1999 08:46am | #6

          *Thomas, I worked for 4 years for a large union roofing contractor doing work at pulp mills, shopping malls etc, and we just lifted the units with a big crane, stripped them in( rooofing term to go around curbs) and dropped them back down. The key to this is to have the sheetmetal or HVAC guys there when you do it. Most large roofing contractors have tin bashers working for them anyway. You have to update EVERYTHING to put in new units?

  3. Thomas_Haas | Apr 21, 1999 04:08pm | #7

    *
    My home is one story and has an old tar and gravel roof - actually two of them, one on top of the other (2 layers). Both layers are failing and its time to tear off and start over.

    b THE PROBLEM GETS COMPLICATED

    My home was built in 1954, and air conditioning was added in the 70's. Two package type units and metal ductwork was placed on 4x4 sleepers on top of the roof. Although originally passed, the work no longer meets the building code. Since the A/C system has to come off for the roof tear-off, it has to be brought up to code when it is re-installed. Code requires that the package units be placed on stands 16" tall and the duct work be raised also. Doing this would expose all the mechanicals to the street and look like hell! Once more, my home is in a historic district and the planning commission would surely object to this visual eyesore.

    b MY BEST SOLUTION

    There is an exception in the building code that would allow me to put the system back on sleepers, but that means that if I had any future roof problems, I'd have to remove the system all over again.

    My solution is to build a structure just large enough to house new soft duct work. I figure the finished dimentions would be about 18" x 18" x the distance to each vent in the system. Once built, my roofer could roll his roofing material right over the structure. Of course the package units would still be exposed, but they are easy to disconnect and move if necessary.

    Anyone see any problems with this solution or have any other suggestions?

    Cost is an issue. Current quotes are $8,500 for the re-roof, and $6,000 to replace the existing ductwork with new metal ductwork and bring it up to code. I figure that building my structure and using soft duct work would cost far less than $6,000.

    By the way, duct work concealed in interior soffits is not an option.

    Thanks

  4. Guest_ | Apr 21, 1999 04:08pm | #8

    *
    My impression is that there are no curbs under these units now? Correct? I can't understand why "code" requires 16" off the roof. Would this be on stands or on curbs? Curbs are pre-made and are about 8" tall. All the ductwork is exposed? What would the historic distric say about lovered enclosures around the equipment? More cost, but same equipment could be reused.

    If I lived in Florida, I sure wouldn't want rooftop equipment 16" off the roof! Seems to me this makes it easy for mother nature to remove it with high winds.

    -Rob

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