# Flat roof, so many options



## jasonl34

Im going to be putting on a new roof and realize theres a few different materials one can use, or I could go another route.

what would you do?

another flat roof?


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## FriscoBlue

jasonl34 said:


> Im going to be putting on a new roof and realize theres a few different materials one can use, or I could go another route.
> 
> what would you do?
> 
> another flat roof?


IB 80 MIL PVC. Great roof!!


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## RooferJim

that roof was never done right to begin with, how long hhas it been on ?

RooferJim
www.jbennetteroofing.com


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## jasonl34

the previous owner tried to tell me only 5 years ago, obviously he was lieing.

i wasnt sure if staying with a flat roof was worth it, or putting a small pitch in it to put on a metal roof.


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## RooferJim

Be prepared to spend huge money for somthing you dont need. All you need is a good flat roof system installed by a good contractor. It will be a lot less than reframing the structure.

RooferJim
www.jbennetteroofing.com


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## buildpinnacle

I definitely would tear off, for sure. Wow, what a hatchet job. Not knowing the budget or environment, I would say at least a 60 mill TPO mechanically fastened over a min 1.5" of Poly-Iso. You would get better thermal resistance by using a two layer insulation system with staggered joints....less thermal loss. Another option would be a 75# base sheet mechanically fastened to the deck (assuming wood by looks), a Ruberoid 20 interply, and Ruberoid granulated cap. You could add densdeck to achieve an FR rating for the roof or go with an FR cap sheet. TPO roof would be cheaper to install IMO. Whatever you install, you have some serious flashing details to correct.


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## jasonl34

Ive talked to quite a few contractors regarding it. 

Cost of course is always a concern, and if something does need or should be changed because it will be a substantially better system then im all for it.
This was a description of what I was offered as a solution.
- *Mechanically attach ½ inch fiberboard over entire surface. *
- *Fully adhere .060 Epdm over entire surface .*
- *Flash all walls and penetrations following the membrane manufacturers specifications.*
- *Install new metal drip edge on roof edges and cover with Epdm cover tape.*
- * Install a new drain sleeves and flash with Epdm flashing.*
- *Install new pipe boots on all plumbing vents.*
- *Clean and remove all job related debris.*
I live in NY so we do deal with a wide range of weather conditions and as far as costs Im probably limited to about 14,000. This system fits under my budget, I just question its quality.


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## RooferJim

fiberboard is a red flag. Its absorbs water like a sponge and should not be used, regardless of how cheap it is. You should ask about PolyIso board.


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## buildpinnacle

Agree with Jim....I won't use it under single ply. I don't have problems with it under mod bit or BUR, but generally prefer perlite for those. Iso much better choice.


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## jasonl34

Ive seen quite a few places having 2" iso for sale that might of been used already, is this a bad idea to do?

ive also been looking into any rebates, I couldnt find any on roof systems..


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## jjshaggy

jasonl34 said:


> Ive talked to quite a few contractors regarding it.
> 
> Cost of course is always a concern, and if something does need or should be changed because it will be a substantially better system then im all for it.
> This was a description of what I was offered as a solution.
> - *Mechanically attach ½ inch fiberboard over entire surface. *
> - *Fully adhere .060 Epdm over entire surface .*
> - *Flash all walls and penetrations following the membrane manufacturers specifications.*
> - *Install new metal drip edge on roof edges and cover with Epdm cover tape.*
> - *Install a new drain sleeves and flash with Epdm flashing.*
> - *Install new pipe boots on all plumbing vents.*
> - *Clean and remove all job related debris.*
> I live in NY so we do deal with a wide range of weather conditions and as far as costs Im probably limited to about 14,000. This system fits under my budget, I just question its quality.


 that is an overlay. dont do it. have them tear off old roof and inspect decking below, and replace rotten or rusted decking (not sure which you have.) then reroof with what ever system you choose. its not the material chosen, its the installer which will matter most.


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## 1985gt

If you dont tear that off ever wrinkle you see will come back through in your new roof if you use 1/2 cover board. Tear it off, 1.5" ISO Fully ahdered EPDM or TPO. EPDM will be cheaper but the TPO will reflect the sun. What ever you do do not go with the cheapest person. Going around the skylights and such are going to be a PITA since someone just keep adding mastic to the flashing. The skylight really looks bad. If you could remove any of them you would be alot better off.


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## jasonl34

Im not going with the cheapest, I realize usually theres a reason for that. Its kind of a bigger company and they warranty their work. I think it would have either a 10 or 15 year warranty...Id have to double check that.

I do know that a representative of the manufacturer would come out to inspect the job after it's done. 

They told me they would address the wrinkles by cutting them all so everything would lay flat.


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## Grumpy

Be sure you understand warranty. Very few single ply manuacturers "Warrant" their roof systems on residential. Though some do. The contractors warranty/guarantee is very important in these cases, however the liklihood that they will service the warranty/guarantee is more important thant he duration (years). In other words if they have lots of complaints, move along to the next one.

I encourage you to read: Low Slope Roofing as well as Hire your contractor


In your case I would prefer tear it off. However if code allows you could go over. A minimum would be a 1/4" High Density PolyIsocyanurate cover board. This would help span some of the ridging and wrinkles you have. I used to use 1/2 fiberboard pretty frequently, but the 1/4" HD iso is better, but it's also fairly new.

If you tear it off, is it a cold deck or warm deck design? we do ALOT of similiar type work here in Chicago. By the way where are you? But here in Chicago you will often see soldier course vents in the walls meaning that the space between the ceiling and roof is vented. In this case it's a cold deck and you would beenfit from insulation on the ceiling, not roof. You would also then benfit from additional ventilation.

However if there are no vents in the walls you likley (maybe) have a warm deck design which means you may benefit from the addition of additional insulation. Preferrably a double layer of 1 1/2" PolyIso Cyanurate, for a total of 3" and an R value of approximately R18.

The type of membrane you install is up to you. If you are looking for reflectivity I recommend PVC or TPO. White EPDM is also an option, but I really like the reliability of heat welded seams you get from PVC and TPO. PVC will cost more but has a better reputation than TPO though I haven't had any problems with TPO (yet).

The roof can be installed mechanically attached or fully adhered. I am of course assuming your roof substrate is wood. Like I said we do alot of these type jobs and it's almost always wood based on the age and style of what I am seeing. Fully adhered is rated to last longer in many cases, and costs a little more than mechanically attached.

You will want to address your side walls, possibly the addition of metal coping. It looks like the last roofer, I mean hack, wrapped the roof over the walls without any mechanical termination. There is definetly no mechanical termination at the chimney, and I would suggest a minimum of extruded termination bar. 

The skylight should be remove and replaced with something more effecient and actually allows light through. Those 100 year old things are always a problem. You need not use the same style though they are still made. In the grand scheme of the job, the skylight will be cheap.


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## jjshaggy

very well said grumpy. :thumbup: youre right that old skylight needs to be replaced. i still like 1/2" hardboard better though, but only used the 1/4" iso once and was on an overlay for a bur gravel roof. even though the gravel was removed you could still see the waves from old roof underneath. it probably works better over a single ply system though? eh.


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## Grumpy

jasonl34 said:


> Ive seen quite a few places having 2" iso for sale that might of been used already, is this a bad idea to do?
> 
> ive also been looking into any rebates, I couldnt find any on roof systems..


 If the ISO was used under a ballasted system, it's probably ok. If you see water stains or holes, pass. 


That roof's what about 3,500 sq ft? I can tell you I would be $12,000 for a tear off and put back a good roof with all new materials on a roof less than half that size. $14k for a tear off isn't going to happen from a reputable roofing contractor. Then again you are new york and I am Chicago, though I doubt prices vary *that* much. 

A lay over would be cheaper, but based on my experience, in my area, you'd be in excess of code. I'm willing to bet the code is 2 layers maximum, I don't know but call your building department. Has anyone done a core cut? A lay over might not be a legal option. 

You always get a better roof when you tear off, but I am not against going over when code and conditions allow. Your roof would be border line ok for a lay over but expect some uneven-ness because of the ridging even if they do cut and lay flat the blisters... there will still be highs and lows.


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## 1985gt

Im going to vernture out and guess thats the 2nd or 3rd roof on the building. Maybe even more. If thats the case its extra for each layer tore off. I once did a job long and narrow. about 20' wide and 200 or so long. Started at the front of the building. 3 layers of moped on roof. no insulation between, got about 1/2 of the way and there the bad decking was showing up, you couldnt tell by walking on it since the bur was so thick. the back 1/3 we replaced all of the decking. I dont know how many trips one of the guys went to the lumber store but we could have almost used a whole bunk of plywood on the job. Needless to say it was a PITA and more then one foot when through the drywall (the drywall and insulation in the rafters was being replaced anyway, still not a good thing when the people in the store start seeing feet poking through). Anyway point of the story, have a core cut done there could be more under then you expect or possably even want to know.


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## jjshaggy

the chimney in front of the skylight looks like the leaning tower of pizza. is it being used? get rid of it maybe or vent it otherwise? what do you guys think?


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## 1985gt

IM going to guess that the building is pretty old and they have regular furnas vent in them. Remove and deck if possable, worth the money to get rid of the mess. The skylight if its needed, new curb. One could even build a wood curb around the orginal one. New panels for sure im sure they leak or have years of built up caulking on them. I looked at one kind of like this with a skylight over the stair way, this was a 6 plex I belive. the drain was a hole going though the chimney with some kind of piping, couldnt really tell since the top layer of roof was a piss poor spray foam, I didnt even take a test cut because the access was a old out side fixed ladder that the rungs were 18-24 in apart and when you got 1/2 way up 25-30' or so it moved about 6" away from teh building. Im acutally kind of proud of my self for even going up that pos. I wasnt about to carry material up it or do it more then once. I guessed there was atleast 2 other roofs under, and probably a pitch building was built in like 1908 or something. pretty easy to pass that one up. I didnt even waste time trying to figure out how much it would cost. under 30 sq id guess over 50k worth of work


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## Grumpy

I did a ladder like that twice. Why twice, because I am stupid. It was 5 stories to my death if the 100 year old ladder fell. Make it worse it wasn't a ladder at all, but each rung was imbedded into the brick. I had my clip board inside my shirt, but no core tools. 

After the first time I went up I saw a roof hatch, and said to myself I will go up that roof hatch next time. I forgot about it and when I went back the next year I did the same thing. I won't do it again, it's funny how having kids makes you think about death. I was fearless of such things before.


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## 1985gt

I was always told never to use external building ladders, more so on older down town or grain elevators. I try to avoid them at all costs this was a one time deal and hopefully will never have to do it again some place else. It is funny how kids will do that. I showed the wife some pictures one time of me up 80 in a man lift and some of the guys 60+ feet on a 8-10/12 building we repair shingles on. At the same time was showing her pictures of a grain elevator we were repairing showing her pictures of the "lift" to get you p there. something like a 24"x24" elevator that you have hold the button down. She wasnt very pleased and asked I never show her pictures of work like that again. Its just easier for her not to think about it I guess.


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## Grumpy

If my wife calls me and I say I am on a roof she damned near hangs up instantly. LOL.


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## 1985gt

That in more ways then one is probably a good thing :laughing:


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## Grumpy

Yeah when I am at the bar I can say I am on the roof


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## 1985gt

Grumpy said:


> Yeah when I am at the bar I can say I am on the roof


I feel like a fool for not thinking of that...


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## jasonl34

Ok sorry for the delayed response, and thanks for the help so far. It really is much appreciated.

I have had one do a test cut done with the top being what you see in the pictures. Underneath that is 1/2' fiberboard. 

Then theres the original which was metal...seemed pretty thin. and underneath that is the deck.


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## Acubis

*Worried about trees*

I am worried about debri falling on the roof.

If any of those trees are large enough to be dropping branches down do not go with any single plys's they will constantly require patching.

If you can find someone to do a 4 ply hot tar system, it is tough as nails and can withstand direct impact from branches and the like.

If no tree debris concerns - yeah PVC membrane over ISO


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## Grumpy

If falling branches are a concern densdeck under the single ply or an impact resistant rated single ply would be a benefit.


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## 1985gt

uppers 1/4 or 1/2 densdeck or 7/16 OSB your choice of single plys. We have put roofs on houses under trees no problems except one windstorm that took the whole tree (100 or so year old oak) and hit the house. Lucky it grazed the house. BUR's are great I personally love the heck out of them, they are all but dead, not many people will do them any more and some insurance companys wont allow res to be reroofed with them.


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## Grumpy

I am in the process of getting insurance quotes. I don;t think any of the companies I have spoken with will allow hot tar and very few allow torch. We only use the torch anymore for repairs. If the price is good, I might just ditch the torch completely even for repairs.


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## 1985gt

I was talking more abou the HO insurance, some wont allow a bur put on some will. Honestly id be more conserened with a torch then a mop but to each their own I guess.


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## Grumpy

I think from a WC point of view, mop is easier to get hurt with that hot asphalt. From a General or Property Liability point of view, torch is easier to destroy the building. First I ever heard about home owners insurance not allowing BUR.


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## jasonl34

Those trees aren't that close, I think it just looks like they are from the pictures.


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## 1985gt

Grumpy said:


> I think from a WC point of view, mop is easier to get hurt with that hot asphalt. From a General or Property Liability point of view, torch is easier to destroy the building. First I ever heard about home owners insurance not allowing BUR.


 
Agree with you there. As far as HO insurace we have had a couple of cases where this has happened. Even wanted to take off a BUR because the insurance didnt like it. Not sure the reasoning behind it. Maybe the insurance companys think all roofers are hacks running around with out insurance.


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## Grumpy

Or untrained with torches.... roffers have been known to burn down buildings and roofers typically repair bur with torch modified. That's my best guess.


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## 1985gt

Torchers are scary.


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## TedLeger

*flat roof*

I know this thread was opened in 2010, but just in case someone comes here looking for advice on a flat roof, one thing that I found to be a great roofing is vinyl roofing, PVC, and even TPO is ok (not what I would go with first, but depends on certain factors that things can be easier with TPO) Anyway, It isn't such a mess like asphalt and rock, and goes faster for sure. Some of it comes in 10 foot, so again, if speed is a concern it covers that. If you want to find out more information on it, you can always Google it by searching for vinyl roofing, PVC, or TPO. I found a site, but there are many others if you want to check it out at http://plasticroofingsheets.net/ - I did notice a few things on there that weren't completely accurate, so you have to be careful with what you read.


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## Maxon100

Keep it flat. The layout of the roof looks great, just needs a EPDM rubber roof and you're good to go.:thumbup:


http://stormproofroofing.org/


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