Foam Closures · Metal building trim guide
Outside Foam Closure Strips for Metal Roof Ridge Cap and Flashing
Outside foam closures sit on top of the panel under ridge cap and flashing, sealing open ribs against rain and pests.
Also called: outside closure, top closure, ridge closure, foam closure strip, profile closure
An outside foam closure is the foam strip that seals the gap between the top of a ribbed metal panel and the trim that covers it. Without it, every rib under your ridge cap is an open tunnel for wind-driven rain, wasps and birds. Crews also call it an outside closure or ridge closure.
It's cheap, light and easy to forget, but it does a big job. This guide explains where they go, how they differ from inside closures, how many to order with a worked example, and how to install them so they seal.
What is an outside foam closure?
It is a strip of closed-cell foam cut to match the TOP side of your metal panel. Its bottom follows the ribs and flats. Its top is flat, so the trim above sits on a solid, sealed surface.
It blocks rain and wind from blowing up under the trim. It keeps insects, birds and rodents out of the ribs. It gives the trim something to bed against, so it sits straight. And it cuts down on dust and drafts inside the building.
Where outside closures go on a metal building
The simple rule: outside closures go ON TOP of the panel, under a trim. Inside closures go UNDER the panel, between the panel and the framing or base trim. They are mirror shapes and are not interchangeable.
- Under the ridge cap, one row on each side of the peak.
- Under high-side trim on a single-slope lean-to, carport or shed.
- Under roof-to-wall flashing where a roof meets a taller wall.
- At the top of wall panels under eave trim on some enclosed buildings. Practice varies by builder.
Outside closure sizes, profile and options
Closures must match your panel profile. A closure cut for corrugated won't fit R-panel. R-panel and PBR closures are often the same shape because the rib pattern is similar, but confirm with us before you order.
Strips are typically sold in pieces about one panel wide (about 3 ft for R-panel and PBR), so ask us how ours are packed. Solid closures are standard. Vented closures are used under ridge vents so air can move while bugs stay out. Foam closures aren't painted, so color doesn't matter; the trim on top covers them.
How to figure how many outside foam closures to order
Formula: length of each run / 3 ft (panel coverage) = closures per row. Round up. Multiply by the number of rows. Add 10% for cuts and spares and round UP.
Worked example (gable): a 30 x 40 gable building with 12 ft walls and a 3:12 pitch. The ridge runs 40 ft. 40 / 3 = 13.3, round up to 14 closures per side. Two sides of the ridge = 28. Add 10%: 28 x 1.10 = 30.8, so order 31 outside closures.
Worked example (single slope): a 20 x 24 lean-to carport. The high side runs 24 ft. 24 / 3 = 8 closures. Add 10%: 8 x 1.10 = 8.8, so order 9.
Remember the eaves need inside closures too, which is a separate count.
How to install outside closures
- Install the roof panels first, ending them where your panel maker's ridge or high-side detail says.
- Run a strip of butyl tape across the panel where the closure will sit, a few inches back from the panel end so the trim leg covers it.
- Press the closure onto the tape with the shaped side down into the ribs. Check that the ribs line up and the closure isn't upside down.
- Butt each closure tight to the next. Gaps between strips are leaks.
- Run another strip of butyl on top of the closure.
- Set the ridge cap or trim on top and fasten through the trim and closure into the panel, using color-matched #14 lap or #12 tek screws long enough to bite fully. Space them per your panel maker's detail, often at every major rib.
- Snug the screws without crushing the closure flat. Brush off all metal shavings.
Common outside closure mistakes to avoid
- Mixing up inside and outside closures. The outside closure goes on top of the panel.
- Buying a closure for the wrong profile, like corrugated closures on R-panel.
- Placing the closure where the trim fasteners miss it, so wind can lift the trim.
- Skipping butyl tape, which leaves a path for water around the foam.
- Leaving gaps between strips.
- Over-driving screws and crushing the foam.
What to order with outside closures
- Ridge cap or high-side eave trim to cover them
- Roof-to-wall flashing for lean-tos tied to a wall
- Inside foam closures for the eaves and wall base
- Butyl tape
- Color-matched lap screws and tek screws
Get outside foam closures in Houston from Ironrod Steel
Ironrod Steel rolls its own R-panel and PBR and stocks matching outside foam closure strips, inside closures, ridge cap, trim, screws and butyl tape. Give us your building size and we'll help you count closures and trim together. Pick up at 8122 Hillsboro St, Houston, TX 77029, or ask about delivery across Houston and Southeast Texas. Call or text (281) 902-7619.
Outside Foam Closure FAQ
What is the difference between inside and outside foam closures?
An outside closure sits on top of the panel under a trim like ridge cap. An inside closure sits under the panel, at the eave or the base of a wall. They are shaped as mirror images and don't swap.
Do I need foam closures under ridge cap?
Yes, on R-panel and PBR. Without outside closures, the ribs under the ridge cap stay open to wind-driven rain, wasps and birds. Vented closures are used under ridge vents.
Are R-panel and PBR closures the same?
Often they are, because the rib pattern is similar. Some panel makers differ slightly, so confirm the profile before you order. Corrugated panels need a different closure.
Do outside closures go on top of the screws?
No. The closure goes down first, then the trim, then the screws through the trim and closure into the panel. That locks it in place and seals it.