flat roof replacement question - PeachParts Mercedes-Benz Forum

dlssmith · #1 06-04-2007, 11:28 AM

Looking for an opinion about what product to use to replace the flat roof on my porch. It's about 10x20 feet and I intend to build a deck on it. It's really a second floor porch.

The roof coating has decayed and now needs work. I would like to use a one piece membrane, heavy enough to withstand having a deck built on it, and whatever else that might entail.

Any suggestions?

Medmech · #2 06-04-2007, 11:33 AM

Quote:

Originally Posted by dlssmith

Looking for an opinion about what product to use to replace the flat roof on my porch. It's about 10x20 feet and I intend to build a deck on it. It's really a second floor porch.

The roof coating has decayed and now needs work. I would like to use a one piece membrane, heavy enough to withstand having a deck built on it, and whatever else that might entail.

Any suggestions?

I don't know about Iowa but we replace flat roofs with sloped roofs whenever possible. There is a franchised product out there that guarantees no leaking and from what I am told that to a good job I will see if I still have the info but google would likly tell more.

dlssmith · #3 06-04-2007, 11:52 AM

If it were a roof only, that would work. But, there is an egress from the upstairs bedroom to that roof making it a wonderful place to sit in the evenings outside. The house was built in 1918 and that roof has always been an upstairs porch.

mpolli · #4 06-04-2007, 12:02 PM

I have seen this done a couple of times on This Old House and Hometime. They used torch-down rubber membrane and then put wooden "sleepers" on it and attached decking to that. You might try searching their websites.

Mike

dlssmith · #5 06-04-2007, 12:03 PM

Quote:

Originally Posted by mpolli

I have seen this done a couple of times on This Old House and Hometime. They used torch-down rubber membrane and then put wooden "sleepers" on it and attached decking to that. You might try searching their websites.

Mike

Thanks for the suggestion.

Kuan · #6 06-04-2007, 01:18 PM

That's what I have on my roof, and it's three years old, and it leaks!

According to the neighbor, there have been four roofs already on this house. Every new owner puts a new roof on this house.

ADP · #7 06-04-2007, 01:23 PM

We live in an "A" frame with a two story flat roofed section attached.

Don't ask. My husband and his dad built it in 1972.

Anyway, all kinds of leaking with the flat roofed section. It had tar and gravel on it, over some sort of fiber board over styrofoam, on top of tongue and groove. It leaked forever. Like since the house was built.

Even though it does not sound as if you are planning on solving the slope issue (we built a "false roof" with slope over the tongue and groove once the old roof was removed) we used metal corrugated roofing material that screwed into the plywood over the false roof. You put this stuff over tar paper, and all the fastners have little rubber "o" rings to prevent leaking. It also has insulation material to put at the ends of a section.

Anyway, this stuff isn't super exspensive, lasts forever and is pretty easy to work with. You can walk on it, unlike fiberglass. We've had it on the carport now for about 15 years, the main roof 2. I've seen it in white, green and red. We have white.

We measured our space, had them cut some custom peices - and the material was delivered on a pallet at the foot of our road. Ordered it online.

Now husband and I did the work ourselves, and we might have spent 3K on the whole thing, which included the dumpster rental, all the materials to repair the old roof and all the materials to build the false roof. Oh, and a lot of sawzall blades, since the old tar and gravel/insulation had to be cut up in sections and removed.

We did investigate rubber roofs. I had one on a flat roofed rental in California and it worked for about a year. Then it leaked.

Ann

dannym · #8 06-04-2007, 02:17 PM

It really all depends on the rubber that you buy. Is it 8mil, 10mil or 14mil. Of course 14 will last longer and be more durable.

TPO membranes have fiberglass mesh built in and are very durable. But there are so many kinds of TPO membranes. to choose from.
You buy cheap you get cheap.
Firetone makes a very good rubber membrane, and fully adhered is very durable too.

My 2c

Danny

kerry · #9 06-04-2007, 02:19 PM

Is is absolutely flat or does it have a slight slope?
I put down a torch down modified roof on an only very slightly sloped section of my house in 1990. It is still holding up well, although I noticed a slight drip on a porch section when we had about 4 days of rain a month or so ago. I've also used the torch down membrane on a porch that was virtually completely flat. I did not install that myself. It's been down about 10 yrs and is holding up fine. It had no granular product on the top surface so i painted it with a reflective aluminum roof paint. The one I installed on my own roof had the granular surface. It cost about $100 a square for materials when I did it. I removed the existing tar and gravel roof, nailed down the fiberglass underoof material, then torched the membrane down.

dlssmith · #10 06-04-2007, 03:04 PM

It slopes about 2 inches in 10 feet. I know I can get a one piece membrane for it. It will be flashed along one side that connects to the house. It doesn't leak now, and you can't believe how bad it looks. It shouldn't leak with a new membrane. I'm sure the earlier comment about spending more to get more is correct. And since it's a relatively small 10x20 space, the materials cost shouldn't really be an issue.

Either I'll do it myself, or get my contractor to do it. He's good. Usually does what I tell him to do.

SwampYankee · #11 06-04-2007, 03:13 PM

We've got 40K sq.ft. of flat roof on our building. I don't think the architect who designed it back in the 50's was the brightest bulb on the tree. Who the heck would put a flat roof on anything in New England?

We installed a new Firestone membrane over 75% of it about 6 years ago and knock on wood...

The previous one, while we got 15 years out of it, was patched quite often and really didn't hold up that well.

GottaDiesel · #12 06-04-2007, 03:28 PM

DS,

I am in the boat as you! The way I see it there are 3 real options.

Let me first say, I don't like the building a deck on top at all. And if I were you, I'd stay far far far away from that idea. Load-issues aside, it isn't a good idea... there are too many variables that can go wrong with the roof, and now you're stuck with a deck on top of the part that is sealed. Most people in my area have opted for the first of my options.

1) Hard Fiberglass roofing -- this is akin to having a boat-hull material (resin, woven, etc.) built as the roof. When done properly it will last 50+ years, and you can dance, jump and walk on it as much as you want. It is also the most expensive. It is also the most problematic if it isn't done properly. You want to keep from being talked into a surface mount rail (and they WILL try to talk you into it) -- you want a FACIA mount rail system... you DO NOT want the penetrations of the rail posts to go through the roof. I have some quotes for this if you need more info, let me know.

2) This stuff: http://www.amesresearch.com/sd_app_article.htm

I have not done it, but I have been VERY curious about it... it seems too good to be true, but who knows.

3) The single giant sheet of rubber that wraps down and over the edge of the surface... this is basically a flexible version of #1... cheaper and more DIY... I don't know enough about it, but it would be very nice -- I see it in JLC and FHB all the time...

Hope this all helps -- I have a mutt-mix roofing on my flat deck-roof... and I haven't painted it in a few years... and it looks like it. No leaks... but I'm living on borrowed time.

Pete

John Doe · #13 06-04-2007, 03:52 PM

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?

Brian Carlton · #14 06-04-2007, 04:00 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?

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

kerry · #15 06-04-2007, 04:13 PM

I'd make the deck in removeable sections in case the roof ever needed work. Perhaps a few bolts holding the sections together.