Best shingles for pitch 3 roof

Roofing/Construction Questions
1

I have been requesting quotes for a teardown & reroof job on my pitch 3 roof: most roofers gave me quotes using 30 years architectural shingles. However, one roofer told me that 3 tab shingles are much better for low pitch roofs. Just want to get some advises here: are 3 tabs shingles really better for low pitch roof?

Also, should I use ice & water shield over the entire roof?      Half of the roof don’t have good ventilation (over vaulted ceiling) and I don’t have enough budget to fix the ventilation issue (install soffit vents & baffles)    Will install ice & water shield on poorly ventilated wood cause more issue than good?
2

[quote=“lite608”]I have been requesting quotes for a teardown & reroof job on my pitch 3 roof: most roofers gave me quotes using 30 years architectural shingles. However, one roofer told me that 3 tab shingles are much better for low pitch roofs. Just want to get some advises here: are 3 tabs shingles really better for low pitch roof?

Also, should I use ice & water shield over the entire roof?      Half of the roof don’t have good ventilation (over vaulted ceiling) and I don’t have enough budget to fix the ventilation issue (install soffit vents & baffles)    Will install ice & water shield on poorly ventilated wood cause more issue than good?[/quote]

Yes 3-tabs are good for a low slope like a 3/12.
A Certainteed XT-30 is a good shingle.

Have them use Ice & water shield & double dipped galvanized nails and it should be fine.

3

Honestly, I wouldn’t use shingles on a anything lower than a 4/12 if you are in an area that gets snow and ice. Also I am not sold on ice+watershield being used on an entire roof surface for a shingle roof.

Since being on my own I had one call back for leaks, the time I put down I+W on a whole 5 sq section of a 2.5/12 roof then shingled over it. I knew if wasn’t recommended my the manufacturer but I worked for others who did the same in the past and they never had an issue. So I do it on my job and guess what, it leaked, like every time it rained, multiple places. I tried stop the leaks multiple times, nothing worked. I ended up tearing up the whole 5 sq section (also the time I learned how much of a nightmare it is to tear off shingles installed over I+W :evil: ) and installing mod bit, and it never leaked again.

After that I said I will never install shingles on anything lower than a 4/12 again, and will only roof in a way that I would be confident of their being no leaks even if I did the whole job with out underlay, not to rely on it.

Not to say you are guaranteed to have leaks if you shingle a 3/12 cause I see other do it but there are products far better suited for that pitch than shingles.

4

The house is in New Jersey and we do get snow & ice during winter.

After some reading I am backing off from the idea of covering the entire deck with ice & water shield. I will request double layers of #15 felt to cover the center areas of the roof.

Can someone explain why 3 tab shingle is a better choice for low pitch roof over architectural shingle? Architectural shingles have better wind resist rating and I am not sure 60 mph wind resistance is good enough for inland areas of New Jersey? (not to mention Architectural shingles have a longer life expectancy as well )

5

[quote=“lite608”]The house is in New Jersey and we do get snow & ice during winter.

After some reading I am backing off from the idea of covering the entire deck with ice & water shield. I will request double layers of #15 felt to cover the center areas of the roof.

Can someone explain why 3 tab shingle is a better choice for low pitch roof over architectural shingle? Architectural shingles have better wind resist rating and I am not sure 60 mph wind resistance is good enough for inland areas of New Jersey? (not to mention Architectural shingles have a longer life expectancy as well )[/quote]

Most “arch.” shingles have a continuous seal strip, which traps the little bit of water that goes between two shingles where they butt together. On a low slope, this will cause the nails to rust out, leading to leaks. I+W 2ft past the interior wall line and synthetic underlayment, if you must use a composition shingle. Metal or a flat roof membrane would be better.

6

Architecturals are thicker on bottom than they are on top. When they are applied this results in working AGAINST the slope of the roof.

7

I can’t tell you how many jobs I’ve lost due to this argument.
Ohhh, my neighbor has architect shingles on their house and their pitch looks the same as mine…

And also “the other contractors didn’t say anything about this.
You’re the only one…”

8

[quote=“lite608”]The house is in New Jersey and we do get snow & ice during winter.

After some reading I am backing off from the idea of covering the entire deck with ice & water shield. I will request double layers of #15 felt to cover the center areas of the roof.

Can someone explain why 3 tab shingle is a better choice for low pitch roof over architectural shingle? Architectural shingles have better wind resist rating and I am not sure 60 mph wind resistance is good enough for inland areas of New Jersey? (not to mention Architectural shingles have a longer life expectancy as well )[/quote]

Why put a double layer of 15# felt instead of a single layer of 30#? I’d stick with the ice & water shield myself, I think paper felt these days is rather useless as a backup defense against leaking.

As someone else explained, due to the way an architectural shingle is made, it actually reduces the pitch even further. Read the Manufacturer’s installation guides, I believe they all say to not use architectural shingles for any pitch under 3:12.

I don’t really know much about the other posters on this thread but Axiom is one of the real roofing experts here. Pay attention to his recommendations.

9

I checked manufacturers’ installation guides and they all allow Dimensional Shingles on pitch 3 roof. Double underlayments (or ice & water shield) is required for roof pitch between 2 ~ 4 in their manual. So I believe this’s required for the manufacturer warranty?

I can’t put ice & water shield over my entire roof since part of the roof (vaulted ceiling area) have poor air ventilation. I am also wondering whether 1 layer of the better synthetic underlayment (such as GAF deck armor) will outperform 2 layers of #15 felt in the long run? My roof is a very simple (no valley), only areas with noticeable water problem are the chimney and eaves (which will be covered with i&w shield anyway)

More than half of the houses in my neighborhood have the same roof pitch (mass-manufactured bi-level house during the 60s) and all the newer roof have new dimensional shingles installed. I have checked with one neighbor with dimensional shingles and they haven’t seen any leaks after 5 years.

10

Thx A.D.

You don’t say what area of the country you are from.
Snow & ice will tend to cause a low slope roof to leak sooner/more than just rain.

The simple fact is that most people prefer the look of architectural shingles to that of most low slope roofing.

While it’s not a good idea to install shingles on 3/12’s and lower it can be done.

Use Grace ice & water shield on the lower 1/2 to 2/3’s of the roof and 2 layers of 15# on the remainder.
There are a lot of different products out there that call themselves ice & water shield, only a small elite handful are equal to Grace, it’s the most expensive because it’s the best and necessary for this application.

IMO 2 layers of 15# is better than 1 layer of synthetic or 30# felt because the 2 layers makes it somewhat redundant.
Whether or not this makes a difference I can’t say definitively.

When installing the shingles use hot dipped galvanized nails or better, better would be stainless or copper.
When using a product like Grace the weak link is the nails, the nails rust out and the roof leaks through the nail holes.
Standard electro-galvanised nails rust out pretty quickly and this is the source of a large percentage of leaks I repair.

When laying the shingles use a wider step than usual, 9" - 10" and only use 4 nails per shingle.

If you follow these steps you should get the full lifetime out of your roof on the low slope areas.

All that being said you should really used a low slope material on 2/12’s even though the above procedure will work more often than not.

I prefer torch applied APP modified Bitumen for this, it’s available in different colors and is very durable,
Choose an old roofer for this, I doubt many of the newer ones truly know how to do torch applied mod bit.

11

Axiom, thank you for your suggestions again. I mentioned earlier that I am in New Jersey (inland area) and we get a lot of rain plus snow during winter. Wind resistance rating on 3 tab shingle is a concern for me. I don’t really understand your suggestion on shingle nailing but wouldn’t 4 nails per shingle make it even more vulnerable to wind?

I have a feeling that roofing companies don’t like it when the customer start asking them to mix third party products. Probably that’s because most manufacturer warranty require them use products from the same vendor. It is kind of difficult when the roofer doing your job don’t buy into the idea and think you are making a mistake. Only 1 roofer (out of the 4 I talked to) has a similar idea and I can’t use him because the guy wants to redo my entire roof ventilation system as the same time.

[quote=“-Axiom-”]Thx A.D.

You don’t say what area of the country you are from.
Snow & ice will tend to cause a low slope roof to leak sooner/more than just rain.

The simple fact is that most people prefer the look of architectural shingles to that of most low slope roofing.

While it’s not a good idea to install shingles on 3/12’s and lower it can be done.

Use Grace ice & water shield on the lower 1/2 to 2/3’s of the roof and 2 layers of 15# on the remainder.
There are a lot of different products out there that call themselves ice & water shield, only a small elite handful are equal to Grace, it’s the most expensive because it’s the best and necessary for this application.

IMO 2 layers of 15# is better than 1 layer of synthetic or 30# felt because the 2 layers makes it somewhat redundant.
Whether or not this makes a difference I can’t say definitively.

When installing the shingles use hot dipped galvanized nails or better, better would be stainless or copper.
When using a product like Grace the weak link is the nails, the nails rust out and the roof leaks through the nail holes.
Standard electro-galvanised nails rust out pretty quickly and this is the source of a large percentage of leaks I repair.

When laying the shingles use a wider step than usual, 9" - 10" and only use 4 nails per shingle.

If you follow these steps you should get the full lifetime out of your roof on the low slope areas.

All that being said you should really used a low slope material on 2/12’s even though the above procedure will work more often than not.

I prefer torch applied APP modified Bitumen for this, it’s available in different colors and is very durable,
Choose an old roofer for this, I doubt many of the newer ones truly know how to do torch applied mod bit.[/quote]

12

" I don’t really understand your suggestion on shingle nailing but wouldn’t 4 nails per shingle make it even more vulnerable to wind? "

Proper placement of the nails is more important than the quantity.

We get wind on Lake Michigan & large inland lakes here also, people seem to think it’s some kind of special wind or something as well.
A properly applied XT-30 will perform as well or better than some of the architecturals out there.

“I have a feeling that roofing companies don’t like it when the customer start asking them to mix third party products.”

Can you clarify what this means?
I don’t know what you mean by 3rd party products.

13

What I am trying to say is the roofer who install GAF shingles wants to use GAF I&W shield; same story for Certainteed installer.

I have been told that I may run into issues with manufacturer warranty if I mix GAF Shingles with Grace I&W shield. GAF require 3 or more GAF products installed (as a system) for their warranty to be valid.

Most roofer does not seem to be very happy when I start telling them what product to install. (and I can understand that)

14

[quote=“lite608”]What I am trying to say is the roofer who install GAF shingles wants to use GAF I&W shield; same story for Certainteed installer.

I have been told that I may run into issues with manufacturer warranty if I mix GAF Shingles with Grace I&W shield. GAF require 3 or more GAF products installed (as a system) for their warranty to be valid.

Most roofer does not seem to be very happy when I start telling them what product to install. (and I can understand that)[/quote]

The Certainteed roofer can use can use winterguard HT, this is almost as good as Grace.

Either roofer can use Grace and the warranty will still apply, both manufacturers are aware that Grace is a superior/equivalent product.

Some roofers don’t like to use Grace because it is more difficult to work with & more expensive so they try to claim that their pet brand is just as good.

The 1 roofer that suggested 3-tabs and wants to redo your ventilation is probably the only real roofer you have talked to, with the others being salesman.

Roofers will talk about the roof, salesmen will talk about how great the warranties are.

The GAF guy will probably come in as the most expensive, add that to 2nd rate products and that is a good reason to disqualify that one.
If you choose the GAF people they can use GAF shingles, GAF ridgevent, & GAF synthetic underlayment, & Grace.
Do they want to charge you for the warranty?

The 3-tab guy will probably be your best choice as he probably has more experience & is more likely to address the roof’s needs.

Don’t focus too much on the warranty A properly applied roof will very rarely need an extended warranty.
Workmanship & technique is far more important.

15

“Best Shingle” for 3/12 roof is Standing Seam Metal Roof period.

16

It’s hard enough trying to get people to pay for the low slope material proper for the job.

The cost of standing seam is usually out of the question.

17

Axioms right about the 4 nails per shingle on this low slope application. It’s imperative!!
Why? Because with 6 nails it leaves too many nails that were driven too high and shot too deep, leaving a pit for water to sit into and rusting out the fasteners. It also leaves too many nails too close to the seams causing future leaks.
Never 6 nail a lower pitch roof!

18

I roof Eastern PA, Northern, and Central New Jersey and I can tell you anything under a 4 I would recommend a low slope roof. I have too many knuckleheads in this area who don’t listen to me and start having issues after 5 years. If you do decide to go the shingle route make sure it’s ice and watered on the entire deck, and 4" lines.

19

bthomastra, What were the main causes (and area) of these leaks after 5 years?

Please understand it is really hard to make a choice that will be very different with your neighbors: There are more than 80 houses around me with the same roof pitch (same roof shape & roof size as well) , all of them have shingles on them and the newer roofs all have dimensional shingles installed.

These bi-level houses were mass constructed during 1960s in a decent middle class neighborhood. You think at least some of these homeowners would already adopt a true low slope application after they experienced lots of leaking issue over the years.

I am having enough trouble decide between 3-tab vs dimensional. While walking in the neighborhood, we saw many old 3-tabs roofs with missing shingles (or repaired shingles), no such issue with dimensional shingle roof. It’s also not easy to pay more for a lesser shingles. (XT30 will cost me a few hundreds more comparing to standard dimensional shingles)

20

I have a handfull I’ve done around Va. that historically had slate on 2/12 and 3/12 pitches.
I had to copy that and owners wouldn’t budge. I used dimensionals, and Dutch-lapped the seams by 2"-4", and ran 4" exposure. Several have gone 20 years now with no leaks.
This creates a 8" headlap and any sidways movement of water lets it land on top of a shingle and no worry about leaks.

I only Dutch lap over single layered portions, even when I had to tear off a 2" strip of double shingle so the gap never exceeded 3/16" in height.
The manufacturers, when I called for an OK, were all in agreement that it was the same as dutch lapping in a valley with the Cali cut, or the weave.