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pauster 06-03-2008 08:51 AM

I am tempted to do a small low-slope roof ...

After reading a bit about roofing and having done a fair amount of DIY projects ... and getting the first quote for fixing a leaking roof I am tempted to do it myself.

We have a sunroom addition on our 50 year old house, it is 17'x17' with a low-slope roof (about 8 degrees). Gutter on one side. Currently it's covered in asphalt shingles like the rest of the house which is 4/12 and steeper.

During heavy rain the water appears to come in between the asphalt shingles. Wrong stuff for a low slope roof I guess, so I need to replace that roof real quick before solar heating is installed on it in the next weeks.

The first quote came in at $3500 for a self-adhered 2-ply GAF Liberty roof.
That's over $12 a square foot.

So I want to do it myself ... and a single 17x17' sheet of 60 or 90 mil EPDM seems like a good way to go.

I have a few questions ...

- do I need an ice shield ? we line in NJ and we do get a bit of snow
- do I need to apply anything (drip edge etc) around the edged of the plywood ?
- how do I transition from the steep asphalt shingles to the EPDM roof ? Shingles are oil based and they should not directly contact the EPDM membrane I suppose ? Do I just put a long sheet of aluminum flashing in between ?
- should I consider any other type of roof ?

Thanks !


Grumpy 06-18-2008 04:51 PM

The price quoted seems fair, sicne I am sure there is more than just the liberty system but are flashigns, insulationb oards, and tie-ins as well.

First off having said that youa re to instlal solar over and I guess through the new roof, I would personally want to install a good ice shield since fasteners will be penetrating the roofing system. These fasteneres will eventually definetly allow water to enter into the roofing system and you'll need the ice shield as a secondary backup. I do not normally install ice shield under low slope roofs, if they are not penetrated you don't need them.

You should always have some form of metal flashing at the edge of the roof. A drip edge or gravel; stop will work fine. You can even use the cheap .019 gauge aluminum with a self adhering system like the Liberty.

Contact the manufacturer of the epdm you plan to purchase as each manufacturer has a different specification for membrane to shingle tie-ins. Chanes are you will need a seperation layer between the butyle and the asphalt shingles as petromeum products are known to break down epdm over time. I personally would not install epdm on this rof you are describing, because of the asphalt shignle tie in, the puncturing for the solar panels, and the also because of the ice shield which will be in contact with the epdm.

tinner666 06-18-2008 05:35 PM

The EPDM will adhere directly to the plywood roof deck after you completely clean it off. At the top, you go about 18-24" under the shingle roof.
No underlay under the EPDM, though you can use insulation. It's not always necessary.

You will need an Installer's Manual for EPDM from the manufacturer. There is no way to explain all that's involved here. I've seen quality DIY jobs with it, and also a few horror stories.

You'll also need a lot of friends to get a single piece on the roof. If comes in 10', 6, 7' and 20' widths. Possibly even a few other sizes.

OldNBroken 06-18-2008 08:59 PM

Actually for a DIY I would recommend you use the SA's instead of the epdm. Gaf liberty is a good product, also certainteed Flintlastic is an excellent 3-ply self-adhering system that we have had great success with here in the NW. As both of these products are SBS modified, there actually is no need for ice/water underneath since basically the SA's are ice shield on steroids.

The SA's would be much easier for a DIY'er with common sense to figure out and do a decent job than an epdm would be. Also they are much more abrasion and puncture-proof than epdm.

That low of slope should never have had shingles to begin with, and actually the quote you got does not seem unreasonable. First, you have to understand that the smaller the job, the more you will pay per square foot due to several reasons. Main ones being it still takes your contractor x amount of prelim and setup work on a three square job as it does a 30 square job. Also the smaller the job the more accessories and incidentals you have per sqare foot. Plus I'm sure that includes the tearoff, also tearing off the section of the upper roof where the tie-in comes in, as well as putting that all back together when done. That little three squares actually includes a lot of detail and material per square foot if you are going to break it down like that.

Either way, in this situation, I would recommend you go with one of the good SA systems instead of the epdm. Sounds to me like your contractor has given you a fair quote on THE correct system for your application.

pauster 06-19-2008 08:57 AM

Thank you - job was done by a pro
Thanks for your help !

I also received several quotes for a torchdown / rubberoid roll asphalt job in a surprising price range. A reputable installer came out with his buddy and they finished the job in two hours, applying over the exiting singles. They seemed competent and offered the usual warranties.

So far the roof has held up to the heavy rain we had lately.

He also mentioned that I had existing GAF shingles for which the manufacturer might have used an inferior petroleum and would therefore pay out a certain amount to homeowners to compensate for the shortened lifespan. Let's see how that plays out.


johnk 06-19-2008 11:00 AM

Went over the shingles?Yuck!It would have taken no time to tear-off.Oh well,as long as your happy.

OnlineHouseDoc 06-19-2008 02:41 PM

Put Torch Down over shingles???? wow thats pretty scarey. I guess you can do anything now a days

pauster 06-20-2008 07:24 AM

John, OnlineHouseDoc,

I'd love to understand why a torchdown over shingles is not a good idea ... ? <ever curious> I don't know much about roofing :huh:

As of yesterday there are solar panels on that roof anyway so aesthetics are no real concern :laughing:


coolflatroof 06-20-2008 06:26 PM


You definitely want a good flat roofing system installed if you are getting solar panels. If that roof starts to leak, you will have to remove solar even to find the leak. If you go with DIY epdm, try to get a single sheet - no seams that is. since it is a sun room, i'd put insulation. Do the I&W just in case, but bear in mind that you need deck ventilation.

I recommend IB (PVC). It is fast to install, easy to repair (if needed - all that has to be done is a small patch welded to the damaged area) IB also has it's own Solar product that is integrated into the roof, so there is no penetrations. It is however less efficient (less Watts per sq. ft.) But in any case you won't fit too many panels on a 17x17 roof.

IB is not for DIY though, but i recommend you look into it. It is worth it since i doubt that you want to repair your roof 5 years down the road. Too much hassle with solar panels on it.

Good luck.

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