An exposed-fastener metal roof leaks at the screws, and the screws start leaking years before the panels give out. That is the opening for a retrofit: the steel is fine, the fasteners are tired, and the owner has a choice between restoring what is there and framing something new over it. In Coeur d'Alene, ID the City design sheet carries a 60 psf ground snow load, so either path has to be checked against the structure under the roof before anyone orders material.
Retrofit usually costs less than a tear-off, because the old panels stay and nothing goes to a landfill. It still has lines you want to see: fasteners, sealant, framing, coating and the structural check.
The Call: Restore, Coat or Frame Over
Three routes. Restoration means replacing every fastener with a larger one, resealing laps and flashing, and fixing damaged panels. A coating route adds a fluid-applied layer over the cleaned and repaired metal to seal fasteners and seams and slow rust. A framing route fastens a new system of purlins or clips over the old roof and sets standing seam panels on top, which turns an exposed-fastener roof into a concealed-fastener one.
The choice follows the condition of the old panels. If they are sound and mostly free of rust, restoration or coating is cheaper. If they are rusted through, dented or loose on the purlins, a framing route or a replacement is the answer. We walk the roof, mark every screw line and failed lap, and give the owner the numbers for each path.
Timing in the building's life matters. If the owner plans to sell or redevelop within a few years, restoration buys time at the lowest cost. If the building will be held, the framing route spreads its higher first cost over a longer life. We ask about the holding period before we price, because it changes the answer more than the roof does.
What It Costs: What Moves the Retrofit Bid
Fastener count sets the restoration price, since each screw is touched. Sealant and flashing add labor at every lap, ridge and penetration. A coating route adds surface prep: washing, rust treatment, patching and priming, followed by the coating itself. A framing route adds the new framing system, the new panels and the trim. In every case, the structural check is a line.
We price all three routes on the same roof so the owner can compare, and we break out the change-order triggers. Rusted panels discovered under old sealant are the usual surprise, so we carry a unit price per panel to replace. Insulation is a separate question: a retrofit that leaves a wet blanket insulation in place has fixed the leak but not the problem, and we check it with a moisture survey where it is accessible.
Access and equipment add to the number. A long, steep metal roof needs fall protection, a lift or staging, and a plan for ice in the morning. We price those as a line, not as a surprise.
What the City Sheet Says: Added Weight and Snow
A framing retrofit adds dead load to a frame that already has to meet the city's snow and wind numbers. Saturated snow runs roughly 20 pounds per cubic foot, so a deep wet snow on a retrofit roof is a real load on a frame that may be old. A structural engineer confirms the existing purlins and rafters can carry it.
Older steel buildings were often designed to loads and connections different from today's. We do not assume. If the engineer finds weak points, reinforcing them is a line in the bid, and it belongs ahead of the roof. A retrofit built on a frame that cannot carry it is a bigger problem than the leak it replaced.
Snow retention is part of the code conversation. A retrofit that turns a screwed-down roof into a smooth standing seam surface changes how snow behaves, because the old ribs and fasteners held it and the new seams will not. We add snow guards where the new surface faces a walkway, a door or a lower roof, and we price the guard line separately.
Where It Fails First: Screws, Laps and Penetrations
On an exposed-fastener roof, the order of failure is predictable. Rubber washers on the screws dry out and crack. Screws back out as the panels move with the temperature, and the holes enlarge. Laps open where sealant has aged. Penetrations leak where flashings were fit tightly and sealed with caulk alone. Rust follows the water, and rusted panel ribs lose strength.
Coeur d'Alene has seen minus 30 F in winter and about 18 days a year above 90 F, and that swing works those screws constantly. In the Silver Valley, where Wallace averages about 75.6 inches of snow and Mullan about 112, the freeze and thaw is harder still. We do not sell a restoration on a roof with advanced rust. We tell the owner so, with photographs.
The edge and the ridge deserve a second look. Closures at the eave and ridge get brittle, wind-driven snow finds the gaps, and a ridge cap that has lifted lets in meltwater in the exact spot where drifting is worst. Even a roof that is otherwise ready for a coating needs the closures replaced before the coating goes on.
Where It Fits: Shops, Sheds and Older Industrial Buildings
An owner with a metal-clad shop or service building in Rathdrum, where the BNSF line runs through a fast-growing prairie city, should price a retrofit before the next leak call. So should one near Cataldo along I-90, where the same screws and washers face the same freeze and thaw.
For roofs that are sound and low-slope, a membrane may be the cheaper path, and we show TPO as an alternate. If the building has real slope and the owner wants a metal look, standing seam over a retrofit frame is the top end of the options.
Schedule: Dry Panels and Warm Days
Fastener replacement and sealing need dry panels and temperatures in the working range of the sealant. Coatings need warm, dry days and a dry substrate. A framing retrofit has the widest weather tolerance, since the panels go on quickly, but cold steel is slick and unsafe, so we hold work on icy mornings. We target late spring through early fall and plan a dry-in at the end of each day. A repair campaign on a roof you plan to retrofit later is money to avoid: we patch only what must not leak this winter.
Closeout is a walk with the GC: every fastener line, lap and closure photographed, drains and gutters checked, and any coating thickness readings logged. The sealant and coating warranty papers go to the owner, along with a map of the roof showing what was replaced and what was left. A later repair crew can read the roof from that map.
Commercial Roofing Questions
How do we know if restoration is enough?
If the panels are sound and the leaks are at screws and laps, restoration works. We probe for rust and loose panels first.
Can we coat a metal roof?
Yes, if the metal is clean, repaired and primed. A coating over heavy rust does not last.
Does a framing retrofit need a permit?
Usually, with a structural review. The city checks it against the design sheet. We prepare the submittal with the engineer.
What happens to the insulation?
We check it. Wet insulation under a retrofit keeps causing trouble. We cut out and replace what is wet.
Is retrofit cheaper than tear-off?
Often, since nothing is hauled away. The structural check and the framing can narrow the gap.