Large Flat Roof Replacement: 100,000+ Sq Ft Projects Across Chicagoland

Chicago Flat Roofs replaces large commercial flat roofs, 100,000 square feet and up, across Chicagoland: Cook, DuPage, Will, and Kane counties. We install TPO, EPDM, and modified bitumen systems on warehouses, distribution centers, manufacturing plants, and multi-building campuses. We respond to formal RFPs, and every number we give you arrives as a line-item scope by email. No sales calls, no verbal quotes, nothing your asset manager or investment committee has to take on faith.

What changes at 100,000 square feet

A big roof is not a small roof multiplied. Past about 100,000 square feet, the project stops being a roofing job and becomes a logistics job that happens to involve roofing. Five things start driving everything:

• Phasing. Nobody tears off 200,000 square feet at once. The roof gets divided into sections sized to what the crew can tear off and dry in one day, because in Chicagoland you assume the sky will try to ruin you. Each section is watertight before the crew leaves it.
• Staging and laydown. Truckloads of insulation and membrane need somewhere to live that is not blocking your docks or your fire lanes. We map laydown areas, dumpster positions, and chute locations with your facilities team before a single truck rolls.
• Crane logistics. Material goes up by crane in planned picks, scheduled around your operations. On a distribution building, that usually means loading the roof from the side away from active dock doors, or working picks into your slow windows.
• Weather windows. The Great Lakes region averages around 42 freeze-thaw cycles a year (GLISA, University of Michigan). A schedule that ignores Chicago weather is a schedule that fails. We build float into the sequence and tell you where it is.
• Keeping docks live. Your building does not close for a roof. Sequencing works around shipping schedules, receiving hours, and the one door your operation cannot lose. That conversation happens during the assessment, not after the change order.

Multi-section sequencing on an occupied building

Most large Chicagoland roofs cover buildings that run every day: three-shift manufacturing, cold storage, cross-dock freight. The sequence plan is the difference between a replacement your tenants barely notice and one they write letters about. Ours covers section order and daily tie-offs, interior protection under each active section, odor control through adhesive selection or mechanical attachment, coordination with rooftop unit shutdowns so conditioned space stays conditioned, and a named sequence for penetrations and curbs so no drain sits disconnected overnight. If part of the roof qualifies for a recover instead of a tear-off, the core samples make that call and the scope says so section by section.

How bids on big roofs go wrong

At this scale, the spread between bids usually is not efficiency. It is scope. The low number is low because something is missing, and you find out mid-project. The classics:

• Scope gaps. Edge metal, coping, tapered insulation crickets, drain replacement, or masonry work at parapets quietly excluded, then sold back as extras.
• Insulation allowances. A bid that carries an “allowance” for insulation instead of a stated R-value and layout is a bid you cannot compare to anything. Current energy code sets the R-value. The bid should state it.
• Hidden wet-fill exclusions. The big one. Wet insulation discovered during tear-off gets replaced at a unit price. If the bid does not state that unit price and an estimated quantity based on actual core samples, the low bidder has left themselves a blank check with your name on it.
• Warranty vagueness. “20-year warranty” can mean membrane-only paper that excludes the workmanship that actually fails. A real bid names the manufacturer system warranty and its term.

Our advice, even if we never bid your roof: require line-item pricing, a stated insulation spec, wet-material unit pricing with core data behind the estimate, and the warranty type in writing. Our guide to writing a commercial roofing RFP covers all of it, template included.

What our itemized scope includes at this scale

Before we price a large roof, an estimator walks it, measures it, photographs it, and pulls core samples across the field, because on 150,000 square feet, guessing at moisture is guessing at the whole budget. The scope you get by email includes:

• System options with the trade-offs stated plainly: what TPO, EPDM, or modified bitumen each buys you on this specific building, and which one we would put on it if it were ours.
• The full insulation specification to current code R-value, layer by layer, with cover board called out wherever the roof takes regular foot traffic.
• Tear-off versus recover determination by section, with the core data that made the call attached.
• Wet-material unit pricing and estimated quantities, so the number that usually ambushes big projects is on the table before the award.
• The staging, crane, and laydown plan, mapped against your dock schedule and site constraints.
• Section-by-section sequencing and schedule, with weather float identified instead of hidden.
• Warranty terms: the manufacturer system warranty, named, with its duration.

We install Carlisle, GAF, and GenFlex systems, and large roofs are spec’d for manufacturer system warranties covering membrane and workmanship, the paper that still matters in year 15. The document is built to go straight into a bid tabulation or a capital request without a single follow-up phone call, because there are no phone calls. Everything is in writing. See how a full replacement runs from assessment to closeout.

Safety and site discipline on a working property

A 100,000 square foot roof replacement puts a crew, a crane, and a season’s worth of material on a property where your people and your tenants are trying to work. Site discipline is not a brochure line at this scale; it is the daily plan. Perimeter warning lines and fall protection on the roof, controlled ground zones under every pick and chute, flaggers where trucks cross traffic, and a clean site at the end of every shift, because loose fasteners in a truck court become flat tires and claims. Insurance documentation and licensing go out with any bid on request. If your risk team has its own site requirements, send them with the RFP and we price to them instead of arguing with them.

Portfolio and multi-building programs

Owners with multiple buildings in Chicagoland have a different problem: not one roof, but a roof budget spread across years and properties. We run multi-building programs on a simple model. Assess everything first, so condition data exists for every roof. Rank by actual condition, not by which tenant complains loudest. Standardize the spec across properties where the buildings allow it, so year three’s roof matches year one’s and your warranty file is one file. Then phase the replacements across capital years so no single budget takes the whole hit. Campuses in industrial centers like Chicagoland and the I-55 corridor through Bolingbrook are exactly the building stock this program was built for. More on the method in managing roofs across a portfolio.

Running a formal RFP? Send it over

If your process runs through a bid invitation, we fit it. Plans, roof reports, scope documents, walk-through windows, deadlines: send them and you will have a line-item response inside your timeline. The full intake process is on our RFP page. If you are earlier than that, before the RFP is even written, start with the form below. An estimator walks the roof within 48 hours and you get the condition data that makes the RFP better.