Comp Asphalt Shingles vs. Modified Bituminous Roof?

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Old 01-18-09, 07:16 AM
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Comp Asphalt Shingles vs. Modified Bituminous Roof?

I'm a bit hung up on selecting a replacement roof!

The proposed roofs:


I've received a number of quotes, and my two leading candidates are both reputable companies with long-standing in our area. Both submitted equal bids ($8k).

(1) Modified bituminous, 105 mil thickness applied over fiberglass underlayment. Seams sealed with torches. Uses the house's existing "swale-type" roof drains built in around the edges of the roof. 10 year warranty.

(2) Comp asphalt shingles over two plies of paper + felt. Will sheet over the "swale drains" to provide a sloped run off the roof, and will install gutters to the appropriate edges of the roof (bypassing the built-in drains). 20-25 year warranty.

The house (photos below):

3-story undergoing extensive foundation work. Roof is approximately 1350 sq ft. Leveling the house caused the existing 10-year-old built-up roof to fracture diagonally.

Roof pitch is 3 in 10, as measured in the attic on the underside of the rafters. Steep enough meet the criteria for shingles.

As you can see from the second photo, the roof is not visible from the street. In fact, it's only visible to three or four neighbors behind us, as the property slopes up a hill in the back yard. So aesthetics are not really a concern. For what it's worth, most homes in the area use comp shingles (and on a number, wind damage is evident).

The decision process...

From what I gathered so far, modified bituminous is:
1. truly waterproof & seam sealed
2. not as susceptible to wind damage
3. uglier
4. warrantied for shorter periods
5. flexible (though the house shouldn't move much on its new foundation)

On the other hand, comp asphalt is:
1. the roof of choice in this area
2. generally more expensive, but I'd be getting a "friend of an employee" deal
3. going to require gutters, which may detract from the house's appearance

The modified bituminous estimators I spoke with said they have a shorter warranty because it's a newer system without a long track record, but that I should expect 30 years from the product.

My question is, if it's truly water tight and rubberized, why is the warranty shorter, and why don't more people use it? It sounds like it will be more trouble free in the long run.

I'm really in a bind here. Should I go with the status quo, or assume the best of the modified bituminous?

The photos:

A gash in the roof running 30+ feet opened up after the house was set on its new level foundation.

Note that there are a number of "architectural features" on the roof that need to be addressed during installation. The square box is not an air conditioner or chimney, but the back side of the rising "vertical columns" visible in the front view of the house. There are six of these for the installer to contend with, and have been water entry points in the past.

Also note the roof drainage system around the perimeter.


The house as viewed from the street (early in the construction project).

The roof is not visible from the street, so the appearance of the roofing material is not important.

On the other hand, a shingled roof would require gutter installation along portions of the front of the house, which could be a visual detractor.
 
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Old 01-18-09, 07:59 AM
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properly installed bituminous roofs in our area work very well, they can also be patched with basicly a tire patch, in my experience shingles that have that low a pitch are slightly more prone to wind damage,

i would use gutters with both as getting the water away from the house and not allowing it to stand on the roof is paramount both to avoid leaks and avoid future foundation problems.

life begins when the kids leave home and the dog dies.
 
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Old 01-18-09, 06:35 PM
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Originally Posted by Speedwrench View Post
properly installed bituminous roofs in our area work very well, they can also be patched with basicly a tire patch, in my experience shingles that have that low a pitch are slightly more prone to wind damage,

i would use gutters with both as getting the water away from the house and not allowing it to stand on the roof is paramount both to avoid leaks and avoid future foundation problems.

life begins when the kids leave home and the dog dies.
I like what you're saying. I still don't understand why the warranty period is only 1/3 to 1/2 that of a shingled roof.

I hear you on the drainage, yet my preference is to avoid gutters. If we go bituminous, I'll have a very detailed conversation with the installer to discuss his plan of attack for drainage.

Unfortunately, we're just moving in, my in-laws are moving to the new first floor, the first kid is due in 2 months, and there are four dogs waiting to die. Life isn't anywhere near "beginning!"
 
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Old 01-18-09, 07:18 PM
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that is a bumper sticker on my cycle that my son brought home from disney world and gave to me.

hope you get along great with the in-laws,

if we're not supposed to eat animals why are they made out of meat?
 
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Old 01-19-09, 02:40 PM
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With proper underlayments a shingle roof will work on that slope.
A modified roof is designed for flat roofing and standard warranty's are around 12 years but can be had up to 20.
A modified membrane roof will outlast a shingle roof on that slope in my opinion.
Most flat roof warranty's are material and labor while shingles are material only. And collecting on a shingle warranty is like pulling teeth.
Modified bitumen roofing has been around for over 20 years. Not so new to the market.
 
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Old 01-20-09, 12:33 AM
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Originally Posted by GMAN69 View Post

...A modified roof is designed for flat roofing and standard warranty's are around 12 years but can be had up to 20.
A modified membrane roof will outlast a shingle roof on that slope in my opinion.
.
:
Modified bitumen roofing has been around for over 20 years. Not so new to the market.
Great! Thanks to both of you.

I had another roofer come out today, this one highly recommended (separately) by our designer, our general, and one of the subs.

Unfortunately, his bid came out pretty high, but he also suggested the modified bitumen, citing some of the secondary slopes which he estimated to be as low as 2:12.

The only issue now is picking a color and setting a date. And while I want to be civil to the three or four neighbors behind us who CAN see the roof, the refelctivity of the white finish has me intrigued. Hmmm... maybe light grey.
 
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Old 01-20-09, 08:29 PM
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1ST yOU`RE REMOVING ALL THE OLD,THEN either system ?I would reline the existing drain sleeves in your box/yankee gutters,line them with smooth surfaced APP ,from the outside edge thru the gutter,and the remainder of the 3 ft. would end on the roof,From there,I would put bitumen on the lighter pitched areas(2 on 12),and shingles on the rest of the 3 pitch,proper nailing of the shingles is usually the reason for shingle blowoffs-GAF/ELK has a really nice lifetime timberline shingle with 110 mph wind resistance
 
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Old 02-04-09, 09:18 AM
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Here's a quick follow-up. Thanks again for the info everyone provided.

The roof was mostly completed yesterday. We've had lovely weather for the past two weeks, which took some pressure off of the roofers and allowed our carpenter to fill in a missing eve where the chimney once stood, and repair a spot of dry rot.

I chose an installer who put down Certainteed Flintastic "white" (grey, really) 105 pound hot-applied bitumen. I was interested in Certainteed's LEED / Title 24 compliant CoolStar material, but the quoted price would have jumped $1000 and a 3-week lead time would have been necessary due to it being an uncommon choice (for my roofer, anyway).

Another view of the fracture:


After stripping off the old, we found the roof was in pretty decent shape. Only a few areas needed repair:


Here's the same crease area pictured two above, where the separation occurred:


The completed roof, including a solar powered attic fan to keep temps in check:
 
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