Buildings We Coat

Post-frame construction puts a lot of steel over a large span with relatively few structural members, and the roof panel does more work than it looks like it does. Panels are typically thin-gauge exposed-fastener, screwed directly to purlins with no deck underneath, which means every screw is both a structural connection and a hole in the weather barrier.

These roofs also flex noticeably. Wind uplift, snow load, and thermal movement all act on a panel with nothing but purlins behind it, which is exactly why the screws work loose and the laps open up.

Spec: Pressure wash, SP3 power-tool clean any tight rust, 7001 Primer over galvanized or coated panel, OR-80SLM at 50 mil field with a 20–30 mil stripe pass over every fastener line and lap.

Commercial bar joist construction puts corrugated steel deck over open-web joists, then insulation and a membrane on top. Two things go wrong. Water that gets past the top membrane sits in the deck flutes and corrodes the deck from above. And in wash-down or high-humidity buildings, condensation forms on the underside of the deck and on the joist chords themselves.

Joist corrosion is the serious version of this problem, because a bar joist has very little steel in its web members to lose. Section loss that would be cosmetic on a beam is structural on a joist.

Spec: Top side — remove wet insulation, re-deck if compromised, then closed-cell foam and OR-80SLM at 60 mil. Underside — closed-cell foam over deck and joists to move the dew point, or SP3 prep with OR7K at 40 mil directly on the joist steel where access allows.

Animal housing produces a genuinely aggressive interior environment: continuous high humidity from respiration and waste, ammonia in poultry and swine houses, and regular wash-down in dairy parlors. Ammonia and moisture together attack galvanizing quickly, and the animals guarantee the humidity never lets up.

Condensation dripping onto livestock and bedding is not just a corrosion issue — it is an animal health and air quality issue. Producers who fix the condensation usually report the ventilation and the bedding both improve.

Spec: Underside closed-cell foam to eliminate condensation, top side 7001 Primer and OR-80SLM at 50–60 mil. Verify chlorides below 7 µg/cm² in wash-down areas before coating.

Storage buildings hold a controlled temperature and humidity for months at a time, which makes them the most demanding condensation case in agriculture. Potato storage in particular runs high humidity by design — the crop requires it — under a steel roof sitting at outdoor winter temperature.

The condensate drips directly onto stored crop, and the resulting spoilage costs more in a single season than the roof assembly does. Foam on the underside is not an energy upgrade here; it is crop protection. On the exterior, the membrane stops the leaks and adds reflectivity that reduces the cooling load.

Spec: Closed-cell foam to the underside of deck and purlins at full continuity, exterior 7001 Primer and OR-80SLM at 60 mil. Consider tapered foam on top where the low-slope roof ponds.

Large-footprint commercial roofs are an operations problem before they are a roofing problem. Tear-off on an occupied distribution center means racking covered, aisles closed, and inventory at risk from a roof that is open to weather in sections.

Restoration coating happens above the building without opening it. The membrane goes on section by section and each section is weathertight within a minute of being sprayed. Add tapered foam where the roof ponds around drains and units, and the energy savings on a conditioned building of that size are measurable.

Spec: 7001 Primer, OR-80SLM at 50–60 mil field, OR7K at 60–80 mil on curbs and penetrations, FJ1 at 80–100 mil in service walkways between rooftop units.