What Are Dimensional Shingles?
If you’ve gotten a couple of roofing estimates in the last few years, almost every one of them probably listed dimensional shingles. They go by a few names — architectural shingles, laminated shingles, dimensional shingles — and they all mean the same thing. They’re the standard asphalt shingle sold in the Chicago area today, and they’ve largely pushed the older 3-tab shingle out of the residential market.
Here’s what they actually are, how they’re built, what they cost, and how they hold up on a roof in this climate.
How They’re Built
A dimensional shingle is made of at least two layers of asphalt-coated fiberglass mat laminated together. The bottom layer is a full base sheet. The top layer is a cut pattern — tabs of varying width and length — bonded onto the base with asphalt sealant. Ceramic-coated granules are pressed into the surface to handle UV and give the shingle its color.
That second layer is the whole point. It creates thickness and shadow lines, so the roof reads as depth rather than a flat sheet. It also means the shingle weighs more. A typical dimensional shingle runs somewhere around 240 to 260 pounds per square (100 square feet of coverage). An old 3-tab is closer to 200. More asphalt and more mat means more material standing between the weather and your decking.
Dimensional vs. 3-Tab
A 3-tab shingle is a single flat layer with two slots cut into it, creating three visible tabs of equal size. Every course lines up the same way, so the finished roof looks uniform and flat. It’s the cheapest asphalt shingle made.
The practical differences:
Wind rating. Most dimensional shingles carry a 110 or 130 mph wind rating when installed to the manufacturer’s enhanced nailing pattern. Standard 3-tab is typically rated 60 to 70 mph. That matters here. Straight-line wind events across the western suburbs regularly gust past 60 mph.
Lifespan. Manufacturers put “lifetime limited” warranties on most dimensional shingles now, but a warranty term and actual service life aren’t the same number. In this climate, a properly installed and properly ventilated dimensional roof realistically gets you 25 to 30 years. A 3-tab roof is more like 15 to 20, and I’ve pulled plenty of them off at 12.
Appearance. Dimensional shingles hide roof deck irregularities. If your sheathing has waves or the rafters have settled unevenly — common on Chicago bungalows and older frame houses — a flat 3-tab telegraphs every dip. The shadow lines on a dimensional shingle break that up.
Repairability. 3-tab has one advantage: it’s easier to match and patch. Dimensional shingles come in blended color granules, and after a decade of sun the original color has shifted. A repair patch will show. That’s a real consideration, but not enough to choose 3-tab for a whole roof.
3-tab still has a place. Detached garages, sheds, rental properties where you’re managing cost, and roofs where you’re matching an existing 3-tab section. For a house you plan to stay in, dimensional is the better spend.
The Tiers Within Dimensional Shingles
Not all dimensional shingles are the same product. Manufacturers run them in tiers.
Standard dimensional. GAF Timberline HDZ, Owens Corning Duration, CertainTeed Landmark. These are the volume sellers and what most estimates quote by default. Roughly 5/8″ thick profile, two laminated layers, 110–130 mph wind rating.
Upgraded dimensional. Owens Corning Duration Storm, CertainTeed Landmark Pro, GAF Timberline AS II. Heavier mats, some with SBS-modified (rubberized) asphalt. The SBS shingles stay flexible in cold weather, which matters for impact resistance in January. Some of these carry a Class 4 impact rating, which can earn a premium discount from certain insurance carriers — worth asking your agent before you decide.
Designer/luxury. CertainTeed Grand Manor, GAF Grand Sequoia and Camelot, Owens Corning Berkshire. Three or more laminated layers, heavier profile, meant to imitate slate or cedar shake. These run considerably more per square and add real weight to the roof structure. On the right house — a Tudor in Oak Park, a stone-front colonial — they look right. On a ranch, they’re money you won’t see back.
What They Cost in Chicagoland
Installed cost on a standard dimensional shingle roof in this market generally runs in the range of $5.50 to $9.00 per square foot, and the spread is wide for real reasons:
- Pitch. Anything over 6/12 requires staging and slows production. Steep Chicago two-flats and Victorians push the top of the range.
- Layers to remove. Tear-off of two or three existing layers costs more in labor and disposal than one.
- Deck condition. Older homes here often have 1×6 plank decking with gaps, or plywood with rot around the eaves from years of ice damming. Sheathing replacement is priced separately on most estimates. Ask how it’s handled before you sign.
- Complexity. Dormers, valleys, chimneys, skylights, and sidewall flashing all add labor and detail work.
- Access. City lots with no driveway and tight gangways slow everything down.
An upgraded impact-rated shingle typically adds $0.75 to $1.50 per square foot. Designer shingles can add several dollars.
Be skeptical of a quote that’s dramatically below the others. The shingle isn’t usually where a low bidder saves money — it’s the underlayment, the ice and water shield coverage, the flashing (reusing old flashing instead of replacing it), and the nailing.
What Actually Determines How Long They Last
The shingle brand matters less than most homeowners think. What matters:
Nailing. Four to six nails per shingle, driven in the nail zone, set flush, not overdriven, not high. A shingle nailed above the common bond doesn’t hold. This is the single most common installation failure I see, and it doesn’t show up until a wind event three years later.
Ice and water shield. Illinois code and every manufacturer specification require self-adhering membrane at the eaves extending at least 24 inches past the interior face of the exterior wall. On a low-slope roof or a wide overhang, that’s more than one course. Valleys should get it too. This is your defense against ice dam backup, and we get ice dams every winter here.
Ventilation. This is where dimensional roofs get killed early. Asphalt shingles are rated based on the assumption that the attic beneath them is ventilated. Without balanced intake at the soffit and exhaust at the ridge, attic temperatures in July run 140°F and up, and the shingles cook from underneath. Granule loss accelerates, the asphalt dries out, and a 30-year roof becomes a 17-year roof. The general rule is 1 square foot of net free vent area per 300 square feet of attic floor with a balanced ridge-and-soffit system, split roughly evenly between intake and exhaust. If your soffits are blocked with insulation or the previous owner painted them shut, ridge vent alone won’t help you.
Flashing. Chimneys, sidewalls, step flashing at dormers. New shingles over old flashing is a leak waiting for the right storm.
Dimensional Shingles and Hail
Northern Illinois gets hail. A standard dimensional shingle handles pea and marble-sized hail without much issue. Once you get to quarter-size and above, you start seeing granule displacement and fractured mat — bruises that don’t leak immediately but shorten the roof’s life and are covered under most homeowner policies.
If you’re replacing a roof that was already hail damaged, or you’re in a corridor that’s been hit repeatedly, look hard at a Class 4 impact-rated SBS shingle. The rubberized asphalt absorbs impact instead of cracking, and it stays flexible when it’s 10 degrees out. The upcharge is real but modest relative to the total, and the insurance discount in some cases offsets a chunk of it.
Who Should Choose Them
For most single-family homes in the Chicago area, a standard dimensional shingle is the right call. It’s the balance point between cost and service life, it’s available from every supplier, and any competent crew can install it correctly.
Step up to an impact-rated SBS product if you’ve had hail claims, if your insurer offers a discount, or if you plan to be in the house 20-plus years and want less to think about.
Step up to a designer shingle if the house architecture calls for it and the budget is there — not because it lasts meaningfully longer, because in most cases it doesn’t.
Stay with 3-tab only for outbuildings, matching an existing section, or a property you’re selling in the near term.
Before You Sign Anything
Ask any contractor giving you a number:
- Which specific shingle line, not just the brand.
- How many nails per shingle, and are you following the enhanced wind nailing pattern.
- How far up the eaves does the ice and water shield run, and does it go in the valleys.
- Is the flashing being replaced or reused.
- What’s the sheathing replacement rate per sheet if rot is found.
- What ventilation is existing, and what’s the plan to balance it.
- What’s the workmanship warranty, in writing, and who honors it.
A dimensional shingle roof done right on a Chicago-area home should get you into the late 2040s. Done wrong, you’ll be back on the phone after the first bad August storm. The material is the easy part of the decision.
Contact AST Contracting for professional dimensional shingle roof installation you can count on for quality workmanship, reliable service, and a roof built to look great and protect your home for years to come.