How Metal Roofing Is Installed in Chicagoland

Chicagoland homeowners searching for how metal roofing actually gets installed usually aren’t planning a DIY project. They want to know what a real contractor does on the roof so they can tell a crew that’s doing it right from one that’s cutting corners. This is that guide — how Castello Roofing installs metal roofing across the North Shore, the south and western suburbs, and the city of Chicago, built around our specific mix of lake-effect weather, wide temperature swings, and municipal code requirements.

Full Tear-Off Before Anything Else

One of the most common questions we hear is whether metal panels can go directly over existing asphalt shingles. Technically it’s sometimes possible. Practically, it’s a bad idea almost everywhere in Chicagoland. Old shingles trap moisture between the new panel and the deck, and our freeze-thaw cycle — heavy in the colder months from the North Shore down through the south suburbs — expands that trapped moisture over and over, putting stress on the panel attachment from below every single winter.

Castello Roofing performs a full tear-off on every metal roof installation, whether it’s a bungalow in Chicago’s city limits or a larger home out west in Naperville or Wheaton. Once the old roofing is off, we inspect and photograph every section of the deck before ordering materials or starting installation.

Underlayment Built for Metal, Not Shingles

Standard felt paper and the lightweight synthetic underlayment made for asphalt shingles are the wrong products under a metal roof. Metal panels sitting in direct summer sun get hot enough to degrade underlayment that wasn’t rated for that kind of heat. In winter, condensation forms on the underside of cold metal panels wherever warm attic air reaches them. The underlayment has to hold up to both extremes, all year, every year.

We install synthetic underlayment rated specifically for metal roofing on every job, from the North Shore to the far southern and western suburbs. Ice and water shield goes down at every eave and extends well into the interior wall line, and it runs through every valley and around every penetration. This isn’t an upsell — it’s standard on every Castello installation, because Chicagoland winters bring real snow load and ice-damming risk off Lake Michigan, and a roofline with thin eave coverage is where water finds its way in.

Standing Seam and Thermal Movement

Standing seam panels run in continuous lengths from eave to ridge, with every fastener concealed inside the raised seam between panels. Nothing punches through the visible roof surface, which is what eliminates the classic exposed-fastener failure — the rubber washers that dry out and crack after a decade or two of Chicago winters.

What a lot of homeowners don’t realize is that standing seam panels are engineered to move on their clips as the temperature changes. Chicagoland’s swing from well below freezing in January to well into the 90s in July means a standing seam panel physically changes length between seasons. Our crews install panels using clip spacing and seam engagement depth built to accommodate that movement.

Stone-Coated and Corrugated Panels

Stone-coated metal panels are installed in overlapping courses from eave to ridge, similar in sequence to asphalt shingles but different in execution. The granule coating that gives these panels a dimensional, shingle-like look is bonded to the steel underneath, so it doesn’t peel, fade, or blow off the way asphalt granules can in a strong Chicago wind event.

For corrugated and other exposed-panel profiles, panel alignment, overlap, and fastener torque all matter more than they look like they should — over-driven or under-driven fasteners are one of the most common causes of leaks we find when we’re called out to fix someone else’s installation.

Flashing That Actually Holds Up in Chicago Weather

Flashing on a metal roof isn’t the same product used on an asphalt shingle roof. A chimney on a standing seam roof needs step flashing that integrates with the concealed clip system rather than weaving between shingle courses the way it would on an asphalt roof. A valley on a stone-coated system needs a valley pan that matches the granule profile of the surrounding panels. Pipe boots need flexible collars designed for metal panel profiles that can expand and contract with the panel instead of tearing at the collar edge as temperatures cycle.

We fabricate custom flashing on site for every metal roofing job, and we photograph every flashing detail before the panels go over it, so homeowners have a permanent record of what’s underneath the finished roof. That record is exactly what matters if a warranty question comes up five or ten years down the road.

Ridge Cap and Ventilation

The ridge takes more thermal stress than anywhere else on a metal roof, because the panels are longest there and expand the most. Ridge cap on a standing seam system uses the same concealed fastener approach as the field panels. Ridge cap on stone-coated systems uses purpose-made hip and ridge pieces that match the granule surface of the field panels.

Ridge venting on a metal roof needs a baffled design that keeps wind-driven rain and snow out during the kind of gusty storms that regularly roll through Chicagoland off the lake. The vent opening also needs to be sized correctly for the attic’s net free ventilation area, or the manufacturer’s shingle and panel warranties can be voided before the roof sees its first winter.

Castello Roofing evaluates the existing attic ventilation before installation begins and confirms the ridge vent meets local code and manufacturer specifications on every job — whether that’s a Chicago two-flat, a North Shore colonial, or a ranch home out in the western suburbs.

Permits and Inspections Across Chicagoland

Requirements vary by municipality across our service area. The city of Chicago requires a permit through the Department of Buildings for roofing replacement, and many North Shore, south suburban, and western suburban municipalities have their own permitting and inspection processes with their own specific rules. The inspection tied to that permit typically confirms ice and water shield coverage, underlayment installation, attic ventilation, and flashing at penetrations — the parts of the job that disappear under the panels and can’t be checked again once it’s covered up.

Castello Roofing handles the permit application for every metal roofing job we do, in whichever municipality the home sits in, and we build the fee into the written estimate up front. A contractor who suggests skipping the permit on a roofing job is telling you they don’t want an inspector looking at what’s under the panels.