flat roof replacement question - Page 2 - PeachParts Mercedes-Benz Forum

t walgamuth · #16 06-04-2007, 06:43 PM

i would not build a wood deck over a rubber roof.

i would use a thick at least 60 mil membrane and use a fully adhered walking surface that is compatable to the roofing system you use. this way the whole system is covered under whatever warrenty they offer.

make sure you follow their guidelines for the surface you are installing it on and if a sloping roof is coming down to it run the membrane up the slope under your shingles at least two feet to avoid capillary action when the snow melts.

if you have a handrail i always try to attach it under the roofing membrane to the side of the roof structure so that it is completely outside the membrane and does not penetrate it.

this is a tough thing to build correctly, and if not done correctly it will cause trouble later.

good luck.

tom w

jaoneill · #17 06-04-2007, 06:59 PM

FWIW - The two most common alternatives are EPDN ("rubber" membrane - tire tube like material) and modified bitumen (commonly called "modified torch-down) with either a smooth or granulated surface. Either one can be had with a 15 year warranty.

EPDN will require a contractor "licensed" by the manufacturer for the initial installation, as well as for repairs, to maintain the warranty, and from experience I can note that the 15 years is all that can be expected.

We usually spec the modified for ease in finding a contractor that can do an acceptable application and more importantly for longevity. If the modified is coated with an acceptable product, and recoated at regular intervals (every 4-5 years in our climate), it will last a very long time, regardless of the 15 year limited warranty period. We have replaced regularly coated modified roofs that are 40-50 years old, not because they leak, but because they are well beyond their design life, and the Owners are nervous.

Whatever choice you make understand that any roofing material is just that, and will not stand up to pedestrian traffic, or the abrasion from "sleepers" that support a deck.

Good luck,
Jim

kerry · #18 06-04-2007, 07:12 PM

The torch down modified bitumen I used, had an additional product to use if you wanted to walk on the roof. It was about 1/4 inch thick and was torched on top of the finished torch down roof. I imagine this would work well under the sleepers for a deck.

dannym · #19 06-05-2007, 09:35 AM

There are pros and cons of building up with a crawlspace and not. With a crawlspace you run the risk of animals getting up there and nesting and creating holes and ruining the rubber. My biggest problem with EPDM (synthetic rubber) is ants. They make nice perfectly round little holes.
Building on top you won't have access to it. The idea of creating the deck in sections isn't a bad idea at all.

When you lay rubber down on something soft and poke it, say you drop a knife, the rubber will stretch and break through. If you lay the rubber down on something hard and drop the knife on it it will hardly effect it. That's why I'm with Tom on the fully adhered. Gluing the membrane down on a hard surface will make it more durable but it will drive up the cost. Plywood is expensive.
It will also make it a lot easier to find a leak, if it ever does.

I like the TPO for a membrane. It's heat welded together and holds up well. It's installed the same way as the EPDM.

I have never been a fan of modified roofs. I see here that people have had success with it but I have never seen one that hasn't leaked.

Danny

dlssmith · #20 06-05-2007, 12:17 PM

Quote:

Originally Posted by John Doe

Maybe I am stating the obvious but I am guessing you would elevate the deck at least three feet above the roof so that if anything ever happened to the roof you wouldn't have to destroy the deck to work on it right?

The egress threshold on to the porch is about 20 inches above the roof. There is plenty of room to build a deck fully joisted. I would attach it to the house and then it would rest on the flat roof at either two or three points, which are where the columns are that transfer the load to the ground.

Judging from the condition of the thing, I don't think this flat roof has leaked much since it was built in 1918. It probably had a tin coating and a lot of blackjack on the joints. Now it's just rolled roofing with black jack, which doesn't leak either - and that's been on for at least 15 years without any maintenence. Go figure.

I can spend what I want on this, it's just not that big. However, I want to be able to walk on it, so a railing is required. And, asthetically, it's important to the look of the house.

John Doe · #21 06-05-2007, 12:21 PM

Quote:

Originally Posted by Brian Carlton

You'd need a set of steps on the inside of the house...............

I read it to mean that there was a set emanating from the bedroom

John Doe · #22 06-05-2007, 12:25 PM

Quote:

Originally Posted by dlssmith

The egress threshold on to the porch is about 20 inches above the roof. There is plenty of room to build a deck fully joisted. I would attach it to the house and then it would rest on the flat roof at either two or three points, which are where the columns are that transfer the load to the ground.

Judging from the condition of the thing, I don't think this flat roof has leaked much since it was built in 1918. It probably had a tin coating and a lot of blackjack on the joints. Now it's just rolled roofing with black jack, which doesn't leak either - and that's been on for at least 15 years without any maintenence. Go figure.

I can spend what I want on this, it's just not that big. However, I want to be able to walk on it, so a railing is required. And, asthetically, it's important to the look of the house.

Roger that.

dlssmith · #23 06-05-2007, 04:28 PM

I've got some research to do. And then to find out what the contractor thinks too. I like to be informed before asking him to work for me - and you all have helped.