# Seeking advice on redo of flat roof



## virgrosa (Aug 1, 2011)

Hi all, 

I currently have a hot asphalt flat roof which is about 11 years old. I am seeking to redo it as there is a lot of ponding at the back end of the roof, which has caused water damage in the ceiling of the back bedroom. Also, the back wall in the bedroom has water damage, which some have speculated is coming from a gap between the gutter and the fascia board (from repeated layers). 

Two Questions: 

1) One proposal would install wall coping over both parapet walls (the house is attached on each side) and front mansard / flat roof transition wall using ".032 baked white aluminum". 

I understand why I would need metal coping if I were going w/ an EPDM or TPO roof, as my neighbors have modified bitumen, and I understand the EPDM or TPO has to be protected from touching modified bitumen. However, the proposal suggests installing the metal coping even if I go with modified bitumen. Why do I need metal coping if I go w/ the modified bitumen proposal? 

2) I currently have a traditional vented skylight (see attached photo). It vents to the outside simply by opening the vent so air can escape. 

I would love to find a similar skylight with a fan where the mechanical venting mechanism is now so the bathroom could be electrically vented with a fan. 

The contractor is proposing installing a "vented flat glass skylight by velux" with a crankout window that would require using a pole. 

Is there a construction out there which place an electric fan in a metal / glass skylight so I can get the light and also extract the moist air using a fan? 

Thanks SO much!  

Cheers,
V.


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## bull24me (Aug 7, 2011)

I need to know pitch on pvc green panel ROOF my chicken run is 10'x16'


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## bull24me (Aug 7, 2011)

Can someone give me the pros and cons on pvc roof the green panels you see at home depot and etc.


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## Omegaroofer (Aug 4, 2011)

1. Because the way they flashed that wall isn't the right way to do it.. 
You need either coping tile, maybe $35 a piece two feet long, or metal and make sure they anchor a wood nailer to the top of the parapet.

2. Good luck with the skylight with a fan. I think he is in line with a skylight that opens.. or they even have stationary vented one's.


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## Grumpy (Dec 12, 2003)

Your roof is pretty typical for what we see in the Chicago area, we work on them all the time. Looking at the height of the curb and the way the roof is wrapped over the wall, I'd suspect 4-5 layers of roofing up there. This may be a reason you are having ponding, tremendous weight causing deflection of the framing of the wooden roof structure.

I'm not sure what green panels are. Can you post a pic or a link? Are you talking about green board EPS? If so, Expanded/Exruded Polystyrene insulation should NOT be used on a wooden substrate due to fire code issues. it is against fire code. There are safer cover board alternatives.

PVC is a very good premium roofing system. Not really a DIY roof in my opinion. A thermoplastic roof such as PVC and TPO require specialty 


A coping is preferred if you don't already have one benath all that roofing. Often we will remove and reinstall the original clay copings. If there is limestone coping we will usually leave alone and secure with termination bar. If there is no coping metal can be easily installed. You could secure to the wall with termination bar and be within manufacturer specification, however then the wall is not protected and brick damage can occur. It's the difference between doing the job cheap and doing the job right IMO. 


Replace that skylight with something new. PERIOD. Again the difference between doing the roof cheap and doing it right. There is no way to permanently flash a 100year old skylight. The velux not only has a crank but they also make a motorized version as well. This would cost a little more and require a licensed electrician. 



If you were myc ustomer here is how I would approach the project. 1 I would determine if the roof is a cold deck or warm deck design. I'll bet $99 that it's a cold deck design, meaning the ceilings are insulated. 2) I would then address how we are going to improve that insulation and I find blown in fiberglass is about the best means possible for this type of design. r30 blown in fiberglass can be installed for the same price as r9 poly iso. 3) If the roof is a cold deck design I would create some kind of ventilation.

4) we would discuss a cover board. some kind of cover board is necessary even if you install a modified bitumen roof. Never will I ever install a roofing system direct to the substrate. Your basic option is 1/2" HD fiberboard. A preferred option would be some kind of ISO cover board. 1/2" is fine, this is not for R value. Also if the framing isn't damaged, only sagged, additional cover board may be used for building up the puddle area.

5) We would figure out what roof type. I personally prefer the peace of mind I get from heat welded seams on PVC and TPO roofing systems. EPDM is a good roof too, but the adhesives will eventually fail. In my area white is right when it comes to roofing. I would assume the same for your area since your roof was silver coated. If you want the best roof possible I would suggest 60mil PVC.

6) Attachement of the roof is important. Single ply like PVC, TPO & EPDM can generally be installed 1 of 3 ways. Mechanically attached, fully adhered or ballasted. ballasted would be silly for your type of roof, it is essentially weighting down the roof with a large ammount of rock. Normally on wood substrates we will install the roof mechanically attached. It's faster and easier and if using a 60 mil product is still rated as a 20 year roofing system. Fully adhered is essentially glueing the membrane to the cover/insulation board. For what it is worth, we always fully adhere our curbs and walls. 

7) Details details details, such as the skylight and the coping. These are things that can vary geatly from one roof to the next. The roof MUST always be secured at the edges. Depending on the type of edge determines how it is secured and without seeing the whole roof I can't really make any recommendations... but the key fact is the roof must always be secured mechanically at the edges. 

8) drainage must also be attended to, and I am assuming you have a gutter. A proper self flashing box style gutter is best for this type of roof. 



Learn more about a box commercial gutter

Learn more about your flat roofing options.


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## virgrosa (Aug 1, 2011)

Dear Grumpy, 

I really appreciate all your advice about redoing my flat roof. As a lay person, I'm going to have to ask a few "dumb" questions to make sure I understand your advice. 

I believe you said that there might be original clay or limestone coping underneath all the layers on my roof, which you would normally try to reuse. If not, metal coping is better. I guess my beef with the estimate I've received is that they would extend metal coping up and over the parapet wall, regardless of whether they do modified bit or TPO, to the tune of $1,280. This makes the quote a lot more expensive than other modified bit quotes (although it is competitive w/ EPDM quote). 

What do you think of this? 

I REALLY appreciate your detailed examination of how you would approach doing my roof -- I will look up some of the vocabulary words you used  and discuss w/ the roofers whose quotes I've received so I can understand it better.... 

Thanks so much!  

Cheers,
V.


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## Grumpy (Dec 12, 2003)

details details details. Roofing is all about the details. A common short cut here in Chicago is sealing the roof to the wall with no mechanical termination of any kind. The roof will fail in 5 years as it becomes unadhered from the wall. 

You are well within manufacturer specification to secure the roofing membrane to the wall with a termination bar. Thus the copings needs not be removed. We seldom will disturb the limestone copings, and this is how we would secure the wall which currently has limestone coping (in most cases). However at walls where the copings are easily removed, such as existing metal or existing clay (terra cotta) we will usually remove the coping and wrap the roof up and over the wall then reinstall or install new coping.

The purpose to wrap the roof up and over the wall is to PROTECT the wall. Should the coping ever leak, water will make it's way into the wall and destroy it over time. It could also cause leaks, which I have experienced and then the customer calls me but it's not my roof. This is why when ever possible we want to do the best job possible and try not to short cut. Yes it will cost more to remove and reinstallt he copings. However in my opinion you simply get a much better job.

All things equal (system warranty/rating, insulation, ventilation, drainage, flashings), if I were quoting modified bitumen I would be substantially higher. I have found most guys selling modified sell the cheap 10 year specification. No, not all, there is a 20 year spec, but a 20 year EPDM will cost alot less than a 20 year modified so you may really really want to dig into the proposals and see what's different, other than just the coping. Also having said that, that is when comparing one legitimate company to another. There are guys around here that are working for beer and cheeseburgers and I expect those guys have brothers and cousins in your area as well! 

Yes term bar is cheaper than replacing the coping. Do the existing coping need to be replaced? I don't know the condition so I can't answer. Metal coping might not be necessary if the existing copings are in good condition and can be reused.


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## virgrosa (Aug 1, 2011)

Hi Grumpy, 

Again, thank you for your advice!  These questions are prompted by my comparing five proposals, all from licensed, insured and bonded roofers. All five would do a tear-off of the existing layers and replace any bad wood. 

Proposal #1: Modified bitumen and install new skylight -- $3600 
5 year workmanship warranty
12 year materials warranty

Proposal #2: Modified bitumen and install new skylight -- $6655
12 year workmanship warranty
12 year materials warranty

Proposal #3: EPDM and install new skylight -- $6770
10 year workmanship and materials warranty

Proposal #4: TPO (Mule Hide 0.60) and install new skylight -- $6780
10 year workmanship 
20 year materials warranty

Proposal #5: PVC and install new skylight -- $8060
15 year workmanship and materials warranty


I am attracted to the first proposal because of the price. The roofer who quoted me Proposal #2 quoted me $3500 for the modified bitumen roof, but added a "recommended extra" of $1280 for 0.32 baked white aluminum wall coping over both parapet walls and front roof transition." 

I feel like I'm belaboring this point, but since I don't know how long I am going to stay in the house, I would really rather go w/ Proposal #2 without the metal coping. All of the other modified bitumen proposals I've received did not say that metal coping up and over the parapet walls was necessary. I do know that metal coping over the parapet walls is necessary if I choose a EPDM or TPO roof because my neighbors roofs (attached on either side, as I live in a rowhouse), both have modified bitumen. When I asked the roofer if we could dispense w/ the "recommended extra", he indicated that it would be necessary. Not really sure how to interpret that. Which is why I am asking for the expertise of this lovely forum. 

I'm going to think through the other points you make re the cover board, warm deck v. cold deck, etc. As far as adding ventilation -- my "crawl space" is about 12 inches from ceiling to roof -- the contractors who have looked at it don't think there's enough room for an attic fan or anything like that.

Thanks again SO much for your help -- you are really assisting this non-profit employee (with the concomitant salary) from wasting a lot of time and money!  

Cheers,
V.


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## Grumpy (Dec 12, 2003)

That's the problem, 5 proposals. There's seldom a reason to get more than 3 and almost never a reason to get more than 4. Not only are you wasting roofer's time, you are confusing yourself. if someone calls me and says I'm the 4th or fifth roofer to look at the job I will politely decline to bid.


Well anyways... Your proposal descriptions are too vague. If you've gathered anything from my ranting over the years you will see that a roof is more than just the membrane. The scope of work and the details will dictate the longevity of the roof. 

What are the other roofers going to do with the wall detail? Termination bar? coounter flashing? You need some mechanical termination at the walls. Metal coping may or may not be the answer, but what's there now under the roof membrane? 

Are all roofers goign to replace the skylight? You need a new skylight?

12 year modified bitumen is often silver coated modified bitumen. This means the roof needs to be recoated which adds to the cost of ownership. Did you also know that the modified bitumen should weather a few MONTHS before the first application of the silver coat? If the roof is not allowed to wether the first application won't last more than a year or two. 

These prices are all lay-overs I assume? I can't see how they'd be tearing off a whole house roof for those prices. I'd be double, but then again I don't know allt he details, I just know an average 80-100 year old house, 1,200-1,500 sq ft plus walls will cost double the quotes you are getting around here. How many layers do you have now? Anyone who wants to lay-over your roof, you should throw their bid right in the garbage can! I can only assume your roof is multiple layers and the top layer looks like filth. 

You don't need an attic fan. Look into http://www.commercialproductsgroup.com/Libraries/Product_Literature/VENTS_and_BREATHERS.sflb.ashx That is of courase assuming nobody is going to insulate the roof deck, you wouldn't want both. 


If I had a dollar for everyone who has told me that they don't know how long they are going to stay in the building, I'd have an extra couple thousand dollars in my pocket. In my experience, most people stay 

If you can post the proposals, or email them to me, I would be glad to review in detail and point out the differences between each. perhaps also a few more pics of the roof and I can give you my typical proposed scope of work for your project.


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## virgrosa (Aug 1, 2011)

Hi Grumpy,

Here are some pics of my roof, as well as the proposals. I have proposals from only three roofers -- two of them offer two options apiece, hence, overall there are five options. 

I really appreciate your willingness to look at these!  You're a dear. 

Cheers,
V.


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## 1985gt (Jan 8, 2011)

My thoughts. Go with the EPDM. reasons why;

The PVC that was spec'd is duralast, stay away.

The guy quoting the TPO was glueing to fan fold insulation, you cant do that, ive never seen a fan fold insulation in 3/8 that you can glue to. you would have to use 1/2 fiberboard or ISO.

Just my thoughts.


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## Grumpy (Dec 12, 2003)

Your gutter should be repalced. You have a residential shingle roof gutter (K style) on your flat roof. Well they can be made to function, though a box gutter would have been better. Yes the shingle roof gutter can be made to function on the flat roof, but in this case it's all jacked up. 

I'll take a look at the proposals and get back to you with some opinions.


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## virgrosa (Aug 1, 2011)

Thank you to you both for your insights. I look forward to your recommendations, Grumpy....  

Cheers,
V.


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## speedtree (Mar 7, 2010)

Grumpy,

you mentioned that the cover board is for more than insulation. what's the reason, better adhesion, protects the epdm when impacted, or something else?

Thanks.


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## Windows on Wash (Aug 30, 2011)

speedtree said:


> Grumpy,
> 
> you mentioned that the cover board is for more than insulation. what's the reason, better adhesion, protects the epdm when impacted, or something else?
> 
> Thanks.


Levels and protects the membrane from puncture from beneath as well.

Great advice and discussion so far Grumpy. :thumbsup:


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## virgrosa (Aug 1, 2011)

Hi Grumpy, 

A couple of months ago, we discussed the possibility of getting your advice comparing the three top contracts I have received. I am still interested in hearing your advice, as I still have not had the work done. 

I realize this might be a lot of work. I would be happy to mail you some imported German chocolate for your troubles!  Also, we can take this discussion to email if it would be more convenient. 

Thanks so much,
V. (see our previous thread below). 



Hi Grumpy,

Here are some pics of my roof, as well as the proposals. I have proposals from only three roofers -- two of them offer two options apiece, hence, overall there are five options. 

I really appreciate your willingness to look at these!  You're a dear. 

Cheers,
V.[/quote]


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