# Flat Built Up Rock Roof



## Terminallance (Aug 31, 2013)

I'm replacing a shingle roof on a church that stands in between a flat rock roof, that has seen better days, but isn't really a problem. However, there is damage, with some parts of the decking exposed, all the rocks are lose/theres no asphalt flow anymore, and all of the vents are beat to hell with hail. I'll have a ton, literally, of supplies on top of this roof, and I'll be disconnecting ACs and removing them on some portions.

My questions are: What will be affected if I replace vents on the flat roof? Will it affect water flow; water is already pooling in the middle. Does the asphalt flow matter, in that the rocks are lose and washing/blowing away? 

There flat roof is atleast 30 years old from what they told me.


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## 1985gt (Dec 21, 2010)

If the decking is exposed it sounds like this roof shouldnt be touched, let alone storing materials and replacing vents on it. It will be a pain to spud all the rock down and get a good seal.


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## Terminallance (Aug 31, 2013)

Thanks for your reply.

What makes the rocks come lose? Is that just wear and tare from water flow, or is it high winds? What all is involved in re-spuding?

There are about 10 places over the roof that are exposed, mostly at the eve, but some in the center.


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## 1985gt (Dec 21, 2010)

Spudding is basically knocking the rock off of an area to expose the felts. Almost impossible to do if a roof is 30 years old, you will tear the underlaying felts off. 

Normal wear and tear. The asphalt breaks down over time and the rock is able to move around then. All asphalt and gravel roofs will have some lose rock. After 30 years Type 3 asphalt is in pretty bad shape.


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## Terminallance (Aug 31, 2013)

So, the basic logic would be age, damage, and state of structure. I have damaged pipes, AC Units, Vents, and exposed and damaged decking all the way to the fibers in some areas. Repairing would be unwise due to removal and replacement of so many units on such an old and aged roofing system.

I can see this now, I do this a lot where some spots on an old shingled roof are damage, in that repairing the sections would tare the rest up.

Thank you again for your continued replies.


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## 1985gt (Dec 21, 2010)

Any time. 

At 30 years its time to start looking at replacement options especially if the roof hasn't been maintained and there other areas needing addressed.


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## builderr (Apr 1, 2009)

I suggest that you complete the shingle work first, allowing 3 or 4 bottom courses of shingles to be installed after the flat roof work. as far as the T&G roof, especially considering that you see decking (?) thru the gravel...and ponding.....I'd consider a new flat system, including new curbing for the A/c units and tapered insulation to direct the drainage of the roof and eliminate the ponding. roof by roof.....product by product....learning the basics of flat roof application is possible, but trying to co-ordinate a large scale install, consideing materials, demolition, system removals and re-installations, and assuring the property owner of a weather tight building at all times can be trick for a first time venture. Im guessing that there are far less roofers available to do this kind of work that are experienced than ready to work. Well experienced, expertly co-ordinated effective and efficient flat roofing crews are a commodity....although small, productive crews eventually can also get the job done.


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## Terminallance (Aug 31, 2013)

When I say "decking" I mean I can see the fibers of the fiberboard, exposed with no rock coverage.

That sounds like a good idea, and you're right there are very few if any crews here who do this sort of work, and the ones that do are contracted as part of a roofing co.

I've thought about just removing the AC units from the roof, but that might require rerigging the whole system.


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## Terminallance (Aug 31, 2013)

What do yall think about spraying a Fire Stone Acrili Coating over the flatrock roof, as it stands now? Would that seal it up?


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## 1985gt (Dec 21, 2010)

No coating on a dead level roof is generally a bad idea. Coating over rocks is worse.


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## EcoTech (Jan 5, 2014)

Assuming that you are just seeing the fiberglass ply sheet and not actual decking you could push the loose rock out of the way maybe a (10x10 area) clean the surface of the deck with a push broom and blower paying attention to getting all lose debris and dust off of the deck. Then you could take a asphalt resaturant, coat the area and re-rock on top of the wet resat. 

The rock is really just there to protect the fiberglass tar paper from the UV rays. The top layer of rock is always lose but as you sweep that away you should see rock embedded in hot asphalt as well. 

You could just buy a yard of rock and re-rock the bare areas. As for replacing vents what are we talking AP vents I assume? 

If that is the case spud out around the vent, cut around the vent in-order to remove the original, underlay new #75 tar paper, cut out the hole for your vent in the tar paper. Install the new vent setting into roof cement, torch down modified, and bull membrane the perimeter of the repair. If you are not familiar with torching just mop cap sheet down with roof cement.

:thumbup:


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## Terminallance (Aug 31, 2013)

Thanks for the reply, gents.

What are your thoughts on peel and stick modified bitumen? I live in the south so it will see 100+ degree days all summer.


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## 1985gt (Dec 21, 2010)

Won't work on flat, or lower slope roofs. And questionable if adhering to a old surface. They do work great on like 1-2:12 slopes though.


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## Terminallance (Aug 31, 2013)

Why doesn't it work?


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## 1985gt (Dec 21, 2010)

On very low slope to flat surfaces? I think it mostly has to due with the laps not being able to stand up to ponding water and freeze cycles.


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## Max00 (Mar 26, 2014)

Since,its 30 yrs old you should completely replace the whole roof.....


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