Which low slope roofing system 1:12 residential shed dormer

I am the homeowner of a house with a large shed dormer on the back of my house that’s started having some leaks, and I need to have the current roll roofing replaced. the dormer is 50x15, 1:12 pitch, with a stone chimney and 2 vent stack pipes (otherwise nothing special). There’s a small section (about 3 foot) at the top of the 8:12 roof for the rest of the house, so there is a roof slope change to consider. The roof is high up off the ground (it’s on the back, and there’s a walkout basement), so it is not visible at all. I’d like to find a roofing system that will hold up well, hopefully be reasonably priced, and can be put on now, in cold temps. I’m in central Indiana, and the temps right now are highs in the 30s-40s.

I have an estimate to have the current roof torn off, 1/2" foamboard applied, with .6 EPDM, for $3300 plus any replacement decking. This seems a bit high to me, but I don’t know for sure. Is this reasonable for rubber? Are there other options that would be better/cheaper?

Hi,

What is your refrence point for deciding the roofer is charging you to much?

You discribed all the things that would make your roof harder to do.
Height, stone chimney, tying into another roof system. tear-off on back of house, time of year.

If I was out of work I might do it for that.

Hi,

Also this contractor is giving you the thicker sheet then most. Most would use the .45 mil sheet.

[quote=“Lefty”]Hi,

Also this contractor is giving you the thicker sheet then most. Most would use the .45 mil sheet.[/quote]

What does the thicker sheet mean? is it more durable?

As far as the question of reference points, I don’t have one, which is why I asked the question here… :slight_smile:

So, is $3k roughly what I should expect to see? And, is EPDM the right solution? And, will they have any issues with getting the rubber to adhere in low temps?

If you wait a few there are other flat roof specialists that can answer all your questions. There names are Aaron B and Cerebus. They deal in flat work and they can answer all your questions.

Hi,

You have some reference point. You said it was high. It may be that you just did not want to part with the money at this particular time.

With edpm the thicker sheet will be better.

The glue will take longer to dry with the colder tempetures.

The stone chimeny is the issue here. If they do not know how to flash stone, you could run into matinence issues.

I would be closer to $5000.

you are @roughly 5 per sq ft. the material you are considering (epdm.glues etc) are about .85 a sq ft. do the math

i would say def. .60 EPDM would be the way to go. it can be done this time of year. i just did one last week. it will take slightly longer for the glue to dry. what you described is exactly what i did in nov. 2 story rear w/ walkout basement, chimney, 2 penetrations. and a tie in. I would question how they plan on doing the tie in. i would run the rubber 18 inches up behind the shingles. i also would have been almost exactly the same on the price. i am in upstate NY so i believe the climates would be similar.

EPDM isn’t the best solution, but it should work alright for your purposes. Most important, if they go with the EPDM make sure it is the black and not the white EPDM, as the black has a higher carbon black content.

You stated the contractor is going with the .060 membrane as opposed to the .045, which tells me they are likely going to fully adhere the roof membrane, yet you mentioned something about foam board which means they may plan on mechanically fastening the EPDM. I’d find out the particulars if I was you just to be sure.

Is there a better system? Absolutely, but you will pay more for them also. Anyway, one option would be to mechanically fasten a base sheet and then install a modified bitumen roof membrane. Since it is a house, I would suggest going with a cold-applied mod. bit. that is at least 180 mils thick and surfaced with granules.

Now back to the EPDM. If you go this route, I would tell the contractor that you wan’t a minimal amount of field fabricated laps in the membrane. The more laps there are in the membrane, the more likely you will have problems down the road. There are other issues that should be addressed as well, i.e., perimeter edge flashing, chimney flashing and counterflashing, etc.

Photos? If you had some it would help!

I agree with Lefty, EPDM is the way to go. The price does seem alittle low to me also. Make sure they are doing an Adhered system and if they are going to have seams in the field of the roof, make sure they use tape on the seams and no “back water laps”. I would also recommend the 1.5 inch insulation and no wood fiber board!!!

I would also be around $5000 for this roof.

Rubber is OK, I guess.

For residential, I think I would like to see torch applied APP in a two-ply assembly over a two ply mech fasteed base( if you did not want to pay for a two ply mopped down base). Not to ply fashion, but two layers, one smooth, one granulated, but this requires intense torch training, and skilled hands. Not everyone can do this roof effectively…

Go with the rubber. You will get less roof, IMO, but less risk of jacking it up by unskilled personnel.

Cerberus,

Here are pics I took this morning: http://web.mac.com/jpherron/iWeb/Site/roof%20pics.html

I took some on the roof and some from the backyard to show the height, and layout. As you can see, there’s a balcony on the back of the house which should help with getting material up, but I don’t know how much of a benefit that is. On the roof, you’ll see a bunch of sealant on nailheads and seams that a roof used last year to repair the roof after a leak. You’ll also see what I would consider a messy job f flashing the stone chimney with a few gallons of roofing cement.

Hi,

The balcony is of no help. It is in the way. Your job is not an easy access.

Consider a fluid applied roof system that would eliminate the tear off and possibly save you some money. Also you could just spot repair until the weather gets better. Products like Hydro-Stops Premium coat system www.hydro-stop.com work very well and are sustainable and very easy to apply. Just a thought. I dont like EPDM because there is no margin of error. If it isnt put down exactly right, odds are it will fail. Fluid applied roofs are seamless and fully adhered. equals no leaks.

I agree…just do not use anything acrylic for waterproofing.

OK, I have now looked at your pics. I could go either way…EPDM or modified bitumen. If youre doing it now, I would go with a flexiblee modified bitumen, but once again, you need a qualified torchamn, whaich are becoming more rare these days.

It is one of those things that people think is easy, until they get a bad one.

Thanks for all the info!

OK, so far I think I’ve heard 3 possible options: EPDM, Modified Bitumen (either torched, or cold applied), or fluid, like hydro-stop. From what I can tell:

Mod Bit might be a good (the best?) option, but I might have a hard time finding a qualified contractor to do the work.

EPDM would be not quite as good as modified bitumen for my needs, but should be fairly easy to find somebody to do

Liquid might work too, and would eliminate the need for a tear-off (making it cheaper?). Don’t know how hard it would be to find a contractor for this

So, my questions would be:

1.) What would be the relative costs of each option? i.e. is Mod Bit more or less than EPDM, and same for a Liquid coating?

2.) What’s the relative durability and maintenance level? I don’t mind some fairly regular upkeep, since I have to get on this roof once or twice a year to clear leaves from the gutter anyway.

3.) is the current roof modified bitumen? From what I’ve seen it looks like it is, but I’m no expert.

4.) Are any of these options DIY-friendly? I’d think not, but I have done quite a bit of non-roof related remodeling work (2 kitchens, 1 basement), and I have a coworker who spent a summer helping a commercial roofing crew do rubber roofs who could help.

5.) Assuming I need to find a contractor, am I better off dealing with a residential roofer who usually does normal slope shingles, or trying to get a commercial contractor to do a small residential job?

1.) What would be the relative costs of each option? i.e. is Mod Bit more or less than EPDM, and same for a Liquid coating?

**Mod bit would cost the most, then EPDM and Hydro-stop would be close with Hydro-stop most likely being a little cheaper. Just remember, you will get what you pay for. **

2.) What’s the relative durability and maintenance level? I don’t mind some fairly regular upkeep, since I have to get on this roof once or twice a year to clear leaves from the gutter anyway.

The mod. bit. will be the most durable. I noticed you have trees near your house, and you should keep the branches trimmed so they don’t come into contact with the roof, but this is especially true with the EPDM.

3.) is the current roof modified bitumen? From what I’ve seen it looks like it is, but I’m no expert.

**It is hard to tell from the photos, but since the laps appear to have been nailed down I’m going to guess that it is 90# rolled roofing. However, it could also be a poorly installed mod. bit. **

4.) Are any of these options DIY-friendly? I’d think not, but I have done quite a bit of non-roof related remodeling work (2 kitchens, 1 basement), and I have a coworker who spent a summer helping a commercial roofing crew do rubber roofs who could help.

**The only one that I would attempt as a DIY’er would be the Hydro-Stop. The other ones definitely need to be done by professionals. **

5.) Assuming I need to find a contractor, am I better off dealing with a residential roofer who usually does normal slope shingles, or trying to get a commercial contractor to do a small residential job?

** You would be well advised to find a commercial contractor. You will want to call around to find a small-to-mid-sized contractor, but be careful since some of these contractors are “big” for a reason. I wouldn’t want a shingle roofer touching a low-sloped roof if it isn’t something they do on a regular basis. **

Now lets talk about some other issues.

  1. I noticed it doesn't appear the chimney is properly counterflashed.  You will want the roofer to saw-cut a reglet into the chimney and install metal counterflashing that is secured with lead plugs and sealed with a polyurethane sealant.  
    
  2. I couldn't tell from the photos, but it looked like the masonry chimney cap may also be in poor repair.  You may want to set up a ladder adjacent to the chimney and check it out before you start roofing. While you are at it, check all your exposed mortar joints and make sure there are no voids.  Even small openings in the mortar joints can leak, so examine the chimney carefully.
    
  3. When replacing the roof, make sure the roofers extend the new membrane at least 12-18 inches up the sloped shingle roof adjacent to the low-sloped roof, and make sure the membrane extends beneath the felt underlayment for the shingles.  The roofer is going to need to remove a couple of rows of shingles to properly flash the transition.
    
  4. Looking at the first photo, it appears there is a peel-and-stick membrane or something that covers the back leg of the gutter and extends up and possibly beneath the existing roofing membrane.  I don't see any perimeter metal flashing, so these are issues you will want to address with your new roof.
    
  5. Hydro-Stop was suggested by one poster, and that wouldn't be a bad temporary repair, but I think you would be better off spending that money on having a good new roof installed.  If you have any nails backing out of the laps, the Hydro-Stop isn't going to stop them from puncturing the roof and cauing a leak.  Futhermore, the Hydro-Stop is only going to be as good as the substrate you apply it to, and your existing roof doesn't look all that great. 
    

Where is it that you live that you are wondering if you can find a qualified roofing contractor?

Anyway, if you have any more questions, feel free to ask.

i would still go with EPDM. like i said i just did one exactly like that. chimney should pose no problems. might get a little trickey around the pipe vent that is so close to it though. alot of roofing companies do both steep slope and low slope, commercial and residential. my ins. company wont let me do any torch down. and i dont like it because it has way more seams. i would def. not recommend trying this yourself . esp. with that pipe so close to the chimney.

Oh yeah, I almost forgot, you can plan on 10 - 15 years from the EPDM and about 20 - 25 from a modified bitumen roof system. So the big question should be: How long do you plan on owning the residence?