This client's residence bears a flat roof with a leak in one corner of the tar and gravel system. Upon GRS' inspection, however, the client desired to explore options for a total roof replacement and its conversion into a rooftop deck.
Correspondence: March 12, 2014
The client and GRS' project manager were spoke briefly about the roof and where the reported leaks seemed to be originating. The client circled the expected problem area on the second photo (attached below). The next paragraph is pulled from the email conversation as it details what they were looking for in GRS' wheelhouse of services.
As it is right now, there is no wall edge or railing around the roof and there are protrusions along the roof where the satilite cables use to come through. I am interested in knowing what it would take to level these out and, prepping the roof for a terrace type deal, along with adding railing or walls. Also what it would take just to do a quick repair on what is leaking, till more permanent fix can be done during the retro-fit. Thanks!
Investigation: March 21, 2014
One of GRS' technicians went on-site to inspect the residence and see what kind of state the existing roof is in. They found that the roof itself actually consists of two systems, the first as a built-up roof (where the leak is), and the second was of a makeshift design. It was largely tarped with a slope package and gravel ballast holding everything down. The identified leak was expected to be a simple fix with some tar gum and reinforced meshing.
The building doesn't have running water, so the roof has been designed to harvest the rainwater, run it through a filtration system, and deliver it to the residents within. This was very important to bear in mind for any proposed repairs.
The client, in meeting with the technician, reaffirmed that they would like to turn the roof into a full deck that reflects the heat of the sun away from the building. To accommodate for the decking proposal, a roof railing would need to be added, and the old gum boxes removed. The roof access (bearing its own, much smaller roof) would also be replaced with the sun-reflecting system at the point of installation.
Quotation Delivered: March 28, 2014
Given the unique task set forth for GRS, it took some time to come up with a series of 'ideal' systems that could be used for this purpose. The first quotation was more of a guideline-type of communication, just to give the client an idea of what to expect. There were, of course, many particular details that would need to be sorted out before a final figure could be delivered.
The scope of work would require a full removal of the current system, going down to the substrate by removing the insulation board, tarping, ballast - everything. With the substrate exposed, there would then be two options to pursue. The first would be a traditional flat roof membrane such as EPDM, TPO, PVC, Tar and Gravel, or SBS Torch-On. With this option, a floating deck would need to be installed on top of it, as the previously mentioned systems are not designed for high levels of traffic, and the warranties would be invalidated immediately.
The second option presented was DecTec, a decking membrane that is also suitable for roofing. This particular system is 80mm, reflective (for the sun rays), and well-suited for this purpose. The only downside to this route is that the substrate would also need to be removed and rebuilt to the exacting specifications that DecTec requires.
Response to Quotation: March 28, 2014
The client had some questions about the details mentioned in discussing both of the options available to them. Below is their series of questions, with the project manager's response.
Morning [Project Manager], In either option 1 or 2, would the plan be to strip in down to bare and eliminate the protrusions, and exposed cut beams? Also, do you have an idea on what is under all that stuff, would it be concreted poured roof? Speaking of poured concrete, is one of these (such as EPDM, TPO, PVC, Tar and Gravel, or SBS Torch on) concrete?
If the IFC blocking and concrete is not an option, would you have any information on what the R-value would be on these other options EPDM, TPO, PVC, Tar and Gravel, or SBS Torch on, Dec Tec?
And the project manager's response:
The EPS sloped insulation has an R value of just shy of 6 per inch. So to get R value of 56 you would need 10 inches.
The sloped insulation package would run around [cost] per square foot, supply and install, and the roof membrane and other components around that also for a total of approximately [cost] per sq foot depending on a number of potential options such as drains, parapet walls, etc.
If the client elects to move forward with roof replacement or rooftop decking services, this article will be updated accordingly.
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