What shingles for long life on 3/12 pitch roof in Olympia, WA

I will be starting construction of a new detached garage/shop that has a 3/12 pitch roof. This is a nice residential waterfront community and I want something that looks nice and appropriate for the area. I hate the look of “flat roof” membrane type roofing and am not a big fan of metal roofs. My contractor and the roofer he uses are suggesting Certainteed Presidential shingles due to the “Low Slope”. My question is: Do these shingles perform better and have a longer life span than a typical “Lifetime” architectural shingle? I do not care about the aesthetic appearance of the “Presidential” and any nice “Lifetime” architectural shingle would be fine. That being said, are these shingles overkill for what my priorities are? I’m assuming they will come in quite a bit pricier then the architectural shingles? I’m quickly looking at retail prices of GAF Laminated Architectural Roof Shingles at $91.92/square and Owens Corning Laminated Architectural Roof Shingles at $77.85. We will be using Ice and Water Shield and the appropriate methods for the low slope roof. I’m looking for advice.

Personally I won’t install any shingles on anything lower than a 4/12 anymore. The only time I had problems with leaks on one of my jobs was when I shingled slope too low for shingles. I would steer you towards one of the many roof products specifically designed for low slopes. EPDM, self adhered modified (gaf liberty), tpo, pvc would all be much better choices. I would even recommend standing seam metal before shingles on a 3/12.

I realize many roofers will tell you its fine to shingle a 3/12, many will say if you use an upgraded underlayment you won’t have any issues. You may very well never have an issue with a shingled roof, but I just don’t agree with doing it. Like I said its not worth it for me to get the job if I am not 100% comfortable with the end result. IMO the guys who recommend shingling low pitches aren’t real “roofers”, they are more just “guys who know how to lay shingles”.

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I wouldn’t say anyone is actually steering me towards shingles on this “low slope” roof, but this is a nice building in an upscale waterfront community and so far I haven’t seen anything other than shingles that would be appropriate for this roof that I like the appearance of. Do you know of any? These “flat roof” type membranes you speak of or standing seam metal roofs just seem very ugly and would be out of place in this community. Is there a nicer looking alternative.

That being said, we will be doing Ice and Water Shield on the entire roof. Any answers to my initial question?

I would think the presidential shingles would perform poorer on the lower slope due to the thickness of the exposure.
I have had no issues with standard laminated shingles on a 3/12 pitch. Make sure the installers are skilled, that’s more important than the manufacturer of the shingles.
That said, 3 tabs are the best shingles for that sort of slope. If it was my home I would go with certainteed xt30’s.
On a 3/12 a double course of felt is required, you could also ice and water the entire thing, though that’s not really a good idea in general.

Any reason you can’t do 4/12?

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I couldn’t go 4/12 due to height restrictions in my county. I think the thought on the Presidentials was the extra thickness and dual sealant strips would be less likely to be susceptible to lifting. Why is Ice and Water Shiled “not a good idea”?. Although both double felt or Ice and Water Shield are supposedly approved methods for low slope roofs, I thought the Ice and Water Shield would be better due to the fact it seals around the nails when they are driven through.

With the lower pitch you want to promote water running off the roof. Hence the superiority of three tabs, as they provide a flatter roof.
Ice and water complicates the roof removal, as the shingles stick to it aggressively.
The product I use recommends consulting an engineer before covering an entire roof in it, due to its tendancy to act as a vapor barrier.

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I have installed predentials on many 3/12 roofs and just finished 50sq of presidential on a 4/12 roof. When I Build this type of roof I ice and water the entire roof. I like the Grace ice and water brand, it will seal immediately and with the smooth top surface shingles will not adhere to it for future removal. With installing ice and water on the entire roof the decking must be dry and clean of saw dust, debris ect. and make sure you have proper ventilation at the soffits and at the top of the roof. Install all drip edge first, ice and water entire roof with product hang over drip edge then trim flush to the drip edge (how I do it anyway, all roofers will be different)
Presidentials should last longer than the average architectural shingle. In my area the average arch shingle such as the GAF timberline, OC duration or the certainteed landmark will/should last 20-25 yrs, Presidentials 30+. There’s very few products that are actual “lifetime”, don’t let what the shingle bags say fool you. Try to match what product is on the house if there are doubts.
I am a certainteed guy so I would recommend the CertainTeed Landmark, Grace the entire roof and make sure there is proper ventilation and you will be fine, if you don’t use grace make sure felt is installed over all ice and water before shingles, the next roofer will be very happy.
The landmark run around $90 per sq while the Presidentials are around $150 per sq.
Hope this helps
Good luck