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JerryH 05-07-2008 12:00 AM

Flat roof questions, advice, ballpark estimate

I'm seeking advice about replacing my flat roof. I have some water discoloration on the ceiling of my top floor in a couple of areas. I noticed it late last fall a few days after some particularly heavy and windy rains, and then it started to get cold, so I didn't figure I'd be able to get it fixed reasonably before the winter. Hopefully there hasn't been too much additional damage.

I'm in Chicago (city), in a row of 6 connected townhomes with 2 adjacent neighbors. The roof is continuous across all 6 units, but my section is just adjacent to my 2 adjoining neighbor's roofs, so I'm not sure if this presents any special problems/considerations. Getting everyone to replace the entire 6 unit's roofs or even mine and my 2 neighbor's roof area would be out of the question. The townhome is 18 years old, so I think I'm due for a new roof anyway. The existing roof is either rubber or bitumen I think.

Unfortunately there is also a rooftop deck built on top of the roof which would have to be torn down. Access to the roof is through a roof hatch. The patch of roof covering my unit is no more than 1000 square feet. There are several metal (zinc I think) tube chimneys and vents and the AC unit is on top of the roof as well. In other words, a few obstacles to deal with, but not much surface area. I plan to remove the rooftop deck and leave it removed for at least a year to make sure the replacement roof is sound and leak-free before I even think about replacing the deck; I never use it anyway.

I have this bad feeling this is going to be very expensive to replace, and I have concerns about how I will be able to trust that whomever I have do this job can demonstrate to my satisfaction that the leaks have been found and stopped. I'm also not clear on whether I should strip and replace or just resurface over what is there (I'm guessing the former from what I've read here so far). So on to my questions.

1) Would anyone want to hazard a ballpark guess as to what this might cost? Are we talking $5K, $10K, $15K, or $20K or higher for what I've described and where I live? I have no idea what to expect, and I don't want to be ripped off nor do I want to go cheap with shoddy workmanship.

2) Should I remove and replace the entire surface or just put new over the top of the old stuff? If I remove and replace, how does one deal with the continuous nature of the roof with my adjoining neighbor's units?

3) Do I need someone specially licenced and insured to deal with this neighbor situation so that if their roof starts to leak after mine is replaced, I'm protected from liability? What specific kinds of extra insurance or legal documentation should I look for and require to deal with this situation? I.E. I think I need something in writing that pretty clearly states that if my neighbor's roof starts leaking within X amount of time after my replacement, that my roofer will be held responsible for paying to inspect and prove that it isn't their work that caused it. I'm just not sure what this document would be or if it's part of a standard contract or what.

4) To determine the source of the leak or extent of the interior damage, who does that and how does one go about doing that? Is there some sort of detector that works through walls, etc. that can trace moisture or does this require a visual inspection? Will a borescope and a few small holes here and there work for this type of thing? I've been considering getting one of these myself anyway for my own peace of mind. Or does the interior ceiling and insulation, etc. have to be torn out and replaced entirely? Does the roofer have this kind of equipment or is that another contractor's job, and who does that interior work? Does the roofer usually subcontract that or do I need to do that?

5) Who or how does one check for mold, wood rot, etc.? Does my roofer do that, or do I need another contractor for that type of thing or does the roofer subcontract that? How is the mold and/or rot detected? Some type of meter/detector, or is this visual inspection also?

As you can tell one of my biggest concerns is how it can be demonstrated to me that the leak is fixed afterward, and that I have no mold, rot, etc. remaining.

6) Is it normal / expected for a roofer to come back, say a year later to inspect and verify there are still no leaks? Is this normally included in the cost or is this extra, and if extra, how much should this cost? Or do I have to wait for a leak to re-appear before I know a year later that everything is still OK. My point here is that before I put back on the roof deck, I want to make sure there is no further leaking, even if there is not yet any visible damage on my interior ceiling for example.

7) How is the roof protected from leaks if it rains/storms while the work is in progress? Is there a period of time where I'm at risk if a storm/rain hits while the work is in progress? Or is everything "sealed up" after each day's work? Also, how long should a job like this take?

8) Is there any alternative to a roof deck structure? I.E. is there some kind of "embedded" heavy duty roofing material I could have put over a patch of the roof that is durable enough for the same type of recreation that one would do on a normal wooden rooftop deck? I hate the idea that if in 3 years I have a problem, I have to pay to tear down the deck to get at the roof to repair it. Or almost worse, if the act of building the deck tears up the roof somehow and I'll know it just after it's built only to have to tear it down again. If there was something that was more easily removed or just part of the roof itself that behaved like a deck, but really wasn't an actual built-up deck, that would be ideal. I think I need the deck for the resale value of the house, but I can't stand the idea of possibly having to tear it out someday again. I've also considered possibly getting thin-film solar instead given the future energy prices I foresee, which would be relatively lightweight even with frames. The roof already holds the existing deck and the AC compressor, so I figure instead of a deck, perhaps it might hold solar panels. My point is that I think I need *something* up there for the resale value of the house other than just a bare roof, but whatever I put up there, I want to make sure installing it doesn't cause a leak or make it incredibly difficult to do maintenance on the roof.

Thanks in advance to anyone willing to help answer some/all of my questions.

johnk 05-07-2008 01:05 AM

I know a very good roofer in the Chicago area,who could answer all of your questions very thoroughly.He should be around anytime,His name is Ed.:)

Michael Thomas 05-07-2008 11:59 AM

Not to further complicate your problem, but one thing to consider is that the source of the roof leak could be at one of the adjacent roofs - water can sometimes travel a considerable distance under a flat roof membrane or along the roof structure below it before it's observed in a living space below. (How how likely this is to be happening depends a good deal on the nature of fire separation between the units immediately below the roof surface.)

Ed the Roofer 05-07-2008 02:04 PM

You have got a boat load of information there for me to consider. I couldn't get on the site earlier due to a virus picked up elsewhere, but my first instinct tells me that this is something that definitely needs pictures and probably a site visit.

Prices are irrelevant at this stage.

You are very correct about the liability of encroaching on a neighbors roof property. If tied in incorrectly, there is a whole new can of worms.


Michael Thomas 05-07-2008 05:23 PM


If you decide to take a look at this job, and I'm free that day, I'll buy you lunch - I'd like to meet you in person since we keep stumblingly across each other on the net.

Ed the Roofer 05-07-2008 10:21 PM

Michael, e-mail sent to you.


Please post some photos so we can properly head you in the right direction.

I also know a really good contractor besides myself, who is on the North Side, if you need a referral.


the roofing god 05-07-2008 10:32 PM

strip the old decking-problem is checking w/in a few ft on either side to assure neighbors stuff is ok,and you need to put a quality seam there,when putting down the new deck use a sleeper system(with extra strips of bitumen material laid out where the sleepers will be to lower the amount of pressure the weight of decking will put on your roof system),with parquet squares you can take up to deal with problems,also be sure the sleepers are laid to go with the pitch direction of the roof,to allow for proper drainage--use a reputable roofer with liability,and cmp insurance,it`s best to strip it,with a deck going on,I would be most comfortable with a modified bitumen roof system,preferably doubled up,and you should have the a/c disconnected,removed,and reinstalled after the work is done for the best job---you should also realise at 18 years of age,you should be talking to all your neighbors as all the roofs are at the end of their life cycle(in most cases)---the roof should be protected/closed up every day--for mold have a mold inspector who will check with a moisture detector,and possibly infra -red(separately)-a good roofer will have contacts for these things(a/c,mold inspection),and it`s usually best to work with people who work well together---your guarantee should be plenty to cover you,although you can pay to have the roofer come back in a year to inspect ,if it makes you feel better---always take references,and speak with the people about their experience,and also check your local consumer protection agency to see if the "roofers" have had complaints,what they were,and how were the complaints dealt with----if you`re lucky to be in ED`s neighborhood,consider it a win/win situation as he is very good,if not there`s 1 or 2 other chicago area contractors we can recommend for you

the roofing god 05-07-2008 10:39 PM

cost---around15-20,000 for decking,and 7-10,000 for the roof

Nonetheless,getting the right job is worth every penny
expect around a 20 year warranty on the roofing
I would also look at heavy thermoplastic,or PVC systems
with IB pvc systems(recommend 80 mil),it is possible for a lifetime warranty

Ed the Roofer 05-07-2008 11:51 PM

For moisture detection, in a non-destructive method and non-penetrating way, you could contact various Home Inspectors and have them use an "Infrared Thermal Imaging Camera" which would detect moisture by "Imaging" the different temperatures of we versus dry building materials.

Here is a link about how the devices operate:

Here is another link that will tell you more about Thermal Imaging:

And another one too:


Michael Thomas 05-08-2008 06:24 AM

One thing to keep in mind about IR imaging of roofs: time of day, weather conditions, coating reflectivity, the amount of ballast, the ability of the roof to absorb moisture, the amount and type of patching and a number of other factors affect the ability to get optimum (and sometimes even meaningful) results - for example the best time to image the roof is a few hours after sunset, while at midday with a clear sky it may be nearly impossible to get meaningful results.

Another is that thermal is most useful for locating specific leaking/deteriorating areas, and at 18 years of age and leaking we already know this roof is coming off at least down to the sheathing or below, at which point we could take direct moisture readings if useful for some reason.

So I would be reluctant to take someone's money to image such a roof unless we were able to define in advance something that would be done differently depending on what I found.

That said, one justification of IR in this situation would be if you could establish that this was a traveling leak from an adjacent roof field (IR would be at best just be suggestive BTW, you would need to directly verify this fact), another would be if you could convince the HOA - or at least the owners of adjacent units - to do an external and internal survey, if one roof is obviously leaking there is a good chance others are as well, and if so you might be able convince other owners to re-roof at the same time.

the roofing god 05-11-2008 11:27 PM

on connective townhouse/condo roof systems,it`s always best to act like leaks are coming from the other neighbor roofs as well,whether they are or aren`t :thumbsup:

JerryH 05-13-2008 07:08 PM

Thanks everyone for the information.

Have been very busy, so I haven't had a chance to get back to this or take pictures. I had my AC checked this morning though and was up on the roof, and I looked around a bit. (I should have taken pictures then, but didn't think of it).

Tearing down the rooftop deck is going to be a real pain. There are railings around my everyone's roof deck that are held up by upright posts nailed or bolted to the base. Where my deck and the neighbor's deck railings meet, they share an upright post. So when I remove my deck, that may affect the structural integrity of the neighbor's railings I think. Also, one neighbor has a satellite dish mounted on one of the upright posts. Great, so now I have to pay to get his dish moved.

Ed, I will contact you privately for your contact information or a referral.

JerryH 05-13-2008 07:18 PM

To Ed:

I tried to send you a private message, but it said something about needing 20 posts before I can do that. How may I contact you privately? I'm interested in perhaps your services if you do work in my area or a referral you mentioned. If I post a visitor message does it go only to you?

the roofing god 05-13-2008 09:21 PM


Ed the Roofer 05-13-2008 09:37 PM

That information is correct that TRG posted for me in my absence.

Thanks TRG.


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