GRIDLINECOMMERCIAL ROOFING
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Roof systems

Low-slope systems, specified for Chicago winters

Freeze-thaw cycles, lake-effect snow and summer heat all work on a flat roof. We pick the system for the building, not the other way around.

At a glance

Five systems side by side

Lifespans assume a maintained roof. Unmaintained roofs lose 5 to 10 years on average.

Swipe the table to see every column

Commercial roof systems compared by expected life, reflectivity, cold performance, foot traffic and cost
SystemExpected lifeReflectiveCold weatherFoot trafficInstalled cost
TPO single-ply20 to 30 yrYesWhite, meets cool-roof rulesGoodModerate$$
PVC single-ply20 to 30 yrYesWhite, grease resistantGoodModerate$$$
EPDM rubber25 to 30 yrOptionalBlack standard, white availableBestModerate$$
Modified bitumen20 to 25 yrWith cap sheetGranulated white capGoodBest$$
Restoration coating10 to 15 yrYesSilicone or acrylicGoodLight$

System detail

Each system in detail

SYS-01

TPO single-ply

Thermoplastic sheets with seams welded by hot air. The most common new roof on warehouses and distribution centers in the region.

WarehousesBig box retailRecovers
Thickness
60 or 80 mil
Attachment
Mechanically fastened or adhered
Seams
Hot-air welded, probed daily
Warranty options
15 to 30 yr manufacturer, NDL
Watch for
Seam workmanship, ponding
Typical install
8,000 to 12,000 sq ft a day
SYS-02

PVC single-ply

Like TPO, but resistant to grease, oils and many chemicals. The right call above kitchen exhaust and process equipment.

RestaurantsFood plantsLabs
Thickness
60 or 80 mil
Attachment
Mechanically fastened or adhered
Seams
Hot-air welded
Warranty options
15 to 30 yr manufacturer, NDL
Watch for
Contact with asphalt products
Typical install
6,000 to 10,000 sq ft a day
SYS-03

EPDM rubber

Synthetic rubber that stays flexible far below zero. Large sheets mean fewer seams, which suits schools and older roofs with many penetrations.

SchoolsOfficesCold climates
Thickness
60 or 90 mil
Attachment
Adhered, fastened or ballasted
Seams
Taped, with primer
Warranty options
15 to 30 yr manufacturer
Watch for
Seam tape aging after 15 years
Typical install
6,000 to 9,000 sq ft a day
SYS-04

Modified bitumen

Two plies of asphalt-based membrane with a granulated cap. It takes foot traffic, dropped tools and heavy equipment better than any single-ply.

Rooftop equipmentPlantsMultifamily
Build-up
Base ply plus cap sheet
Attachment
Torch-free, self-adhered or cold applied
Seams
Lapped and sealed
Warranty options
10 to 20 yr manufacturer
Watch for
Blistering, cap granule loss
Typical install
3,000 to 5,000 sq ft a day
SYS-05

Restoration coating

A fluid-applied silicone or acrylic coat over a sound, dry roof. It buys 10 to 15 years at a fraction of a replacement and keeps the old roof out of the landfill.

Sound roofsMetal roofsBudget years
Requirement
Under 25% wet insulation
Application
Spray or roll, 20 to 30 mils dry
Seams
None, fully monolithic
Warranty options
10 to 20 yr manufacturer
Watch for
Wet insulation under the coat
Typical install
15,000 sq ft a day

Restore, recover or replace

Wet insulation makes the call

An infrared scan and a few core cuts tell us how much of the insulation is wet. That number decides the scope, and the budget.

Under 10% wet

Restore

Replace the wet sections, then coat. The cheapest path, and the roof stays in service the whole time.

10% to 25% wet

Recover

Remove the wet areas and install a new membrane over the existing roof. Code allows one recover layer.

Over 25% wet

Replace

Tear off to the deck, inspect it, and install new insulation and membrane with a full manufacturer warranty.

Chicago's energy code calls for reflective roofs on most low-slope commercial replacements. Every white membrane and coating we specify meets the requirement, and we include the product data with your permit set.

Rooftop condenser unit and roof access ladder on a white parapet with orange coping

Where leaks start

Most leaks start at the details

Open field membrane rarely fails first. Curbs, drains, pipe penetrations and parapet walls do. Every Gridline install includes:

  • Prefabricated corners and pipe bootsNo hand-cut patches at the spots that move the most.
  • Tapered insulation to every drainNo ponding water 48 hours after rain.
  • Seams probed every dayLogged by section, with photos in your closeout file.

Not sure what is under your membrane?

Start with a scan, not a sales pitch

Our assessment tells you how wet each roof is, what it needs and when. Then you decide.

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