KBH Applications

The Affordable Stainless-Steel Roofing System: The Affordable Stainless-Steel Roofing System lays stainless-steel sheet-metal laterally across the roof with side-laps down the roof. The lateral sections are about 25' long and then the end-laps are about 12" to 16". The width of the stainless-steel sheet metal is about 14" to 20" and the side-laps are 3" to 4". The stainless-steel sheet-metal attaches to the roof deck with stainless-steel roofing nails in slotted holes or with stainless-steel wood screws in slotted holes. Of course the roofing layout begins at the eave and works upward to the ridge.

The Stainless-Steel: The stainless-steel sheet-metal is found in coils and bought by the pound. This stainless-steel sheet-metal is raw material without any fabrication or flattening. This stainless-steel sheet-metal has a thickness of about 0.025" to 0.030". Then 430 stainless-steel has almost as much corrosion resistance as 301 to 306 stainless-steel but has less thermal expansion and costs less. Or 316 stainless-steel has the most corrosion resistance and costs the most. Well, 301 to 316 stainless-steel should be used at the ocean, used around chemical plants, and used at the curb when there is road salt but otherwise 430 stainless-steel might be good enough. Next, consider stainless-steel finishes with 2B, BA, and #8 all too bright. However, there is one project where the BA finish just blacks-out at roof viewing angles. (The 430 stainless-steel can make a rust line where nicked with a cut-off disk or where a crease is overworked. However, a grinding wheel touch usually doesn't rust.)

First Set of Details: The side-laps of the stainless-steel sheet-metal roofing can be riveted with stainless-steel closed-end pop-rivets that are said to be water-tight. Also, there are some stainless-steel aerospace pop-rivets designed to hold pressure. However, the protrusion of the rivet against the roof deck might be a problem and so brazing with simple handheld torches and using silver-solder that is about 50% silver might be tested for use instead. That would be a 1" braze about every 16". Now the first roofing course at the eave and the eave face board should be two separate pieces. And so a tab can be fabricated from a 2" diameter stainless-steel fender-washer such that the tab mounts to the roof deck with a slotted hole at the top and then overhangs the roof deck slightly less than the roofing. Then the stainless-steel roofing can rivet to the bottom of the tab in two places such that it pulls the tab along the slotted hole track. Of course, all uses of slotted holes allow for thermal expansion of the stainless-steel sheet-metal. Now, even with the side-laps riveted there is some amount of air gap and so this roofing system can benefit from a synthetic underlayment that is breathable. Then a breathable underlayment is just a little less water protection. Or a non-breathable synthetic underlayment could be used and then roof vents chosen for the roof. However, any metal touching the stainless-steel roofing should also be stainless-steel to avoid galvanic corrosion. Copper and lead might be safe touching a large amount of stainless-steel roofing but even consider insulators in that situation. And lead could be easily cut by the stainless-steel during thermal expansion. If a gutter is used then consider the use of a plastic gutter. Finally, the section end-laps should have a clip on the underneath course such that the upper course slides in a slot.

Second Set of Details: The section end-laps need additional design. The underneath end-lap could have a u-shape bend on the metal edge to catch water should it reach the edge but the flow of water between two pieces of metal is unpredictable because of water surface tension. Or a shallow stainless-steel u-shaped channel might be set down the roof with the underneath section laying on top of the channel edge and then the top section end-lap laid over. And other designs are possible and may be needed. But it's likely that the roofing would be too difficult to work with as one-piece for the entire length of the roof and that's why end-lap sections were called for. The end-lap overlap might be increased from 16" to 32". (The end-laps are proving safe at 16" of overlap but each higher course of end-lap is a little longer then the previous course. The fit of the end-laps is not great but stable in the wind on a 4/12 roof slope and that before being clipped or held-down.)

Advantages of the Affordable Stainless-Steel Roofing System: The stainless-steel roofing does not need painting and will not rust or corrode. The stainless-steel roofing maintains its advantage over corrosion even where cut or drilled. The stainless-steel roofing is very durable. The stainless-steel roofing is light in weight at about 1.0 to 1.25 pounds per-square-foot. However, more weight advantage is because of a small percentage of side-lap and end-lap area. The stainless-steel roofing can be touched-up through the years with the use of a handheld power grinder.

Problems with the Affordable Stainless-Steel Roofing System: The roofing system often lacks square cuts and exact lengths and looks a little rough around the edges. Also, the difficulty of handling the stainless-steel sheet-metal often causes waves in it. However, the roofing looks okay at normal viewing distances. The fit at the gable-end is not great and the fit at the end-laps is not great but stable in the wind on a 4/12 roof slope. The natural ventilation of the side-laps might favor summer over winter and that true if the roof deck is boards instead of sheets.

Batten System for a Warped Roof: The stainless-steel sheet-metal can easily conform to a batten system and so also consider this roofing system for use on warped roofs. Then a 16" grid of spacers can be cut from the ends of 4-by-4's. In fact, cedar is light in weight and strong enough to support a roof covering. A point of no roof warpage should have a spacer about 1.5" tall while roof points with warpage would have spacers cut to height. Now, a grade-matching laser can set spacer heights along the eave and along the ridge. Then a 24' long 2"-by-3" aluminum rectangular tube can be used to measure for spacer heights between ridge and eave points. The slight and natural bend of the aluminum beam makes smooth transistions between the spacers. In fact the resulting grid of spacers is so close to perfect that standing-seam roofing might work on them. But when using sheet-metal on the spacers then the 16" grid of attachment points could be filled in with some extra bumper spacers. Otherwise, movement on the roof would require the use of two sheets of plywood and soft rubber pads. Note that the roof spacers can be attached to the roof with wood screws in deep counterbores.

Useful Tools and Materials: Stainless-steel #8 wood screws can be found most affordably in square-drive truss-head type-17-point. Various lengths are available up to 2 1/2". Of course, countersink screws are avoided since screw head edges are used for holding. Both underlayment nails and roofing nails are affordably available in stainless-steel. A 12" sliding miter saw can cut 4-by-4's. A 1 1/2" straight die grinder (1/4" collet and 25,000 RPM) at about 3 amps power can cut slots in sheet metal using 2" diameter cut-off wheels and working between drilled holes. There are three types of handheld power sheet metal shears. One type cuts mostly straight lines, another type cuts straight lines and curves of several inches in radius, and a third type that can cut tight curves. Technique and cutting angle must be close to perfect. Forstner bits will drill counterbores at variable depths. A three-plane leveling and alignment laser mounted on a photographic tripod with a geared head can then easily match grades. Or a 24' long 2"-by-3" aluminum rectangular tube can be used for level or grade. A 2 1/2" to 3" brushed stainless-steel tube in 0.125 thickness can mount TV antenna or satellite antenna but also be a weak ground for the stainless-steel roof. The idea of grounding a metal roof is to avoid a build-up of static charge. A roof-top lightning-rod system is a completely different fundamental since it would be insulated from the roof. (A metal roof could also be grounded to the fuse box ground with copper or aluminum wire.) Stainless-steel closed-end pop rivets have a wider spec grip range in 3/16" diameter than in the smaller diameters. A two-hand lever rivet tool at about 20" in length can easily set the rivets. Also, sized stainless-steel washers are available for stainless-steel rivets. A power drill at about 4.5 amps and with an adjustable clutch set at about "7", can set #8 wood screws tightly but without cracking the wood. A drill press can be set up to drill counterbores to a set depth. Simple handheld metal bending tools can make short simple metal bends. A handheld roller metal bending tool can bend ridge shapes, shapes from roof deck to eave face board, and drip edges. However, the handheld roller tools are designed for 90-degree bends and so other angles would require user skill. Premium drill bits are easy to find but a sharp drill bit is critical for rivet holes. Drilling in steel should be at slower speeds than wood and should bite and flake immediately and hold in punch marks. Rivet holes also require a reamer operation.

Newest Tips: A length of stainless-steel sheet-metal can easily be pulled up on the roof using lumber as an incline plane. Getting a length of stainless-steel sheet-metal off the coil is done with a re-rolling action such that the outside of the coil becomes the inside of the coiled length taken off. That's with the coil on its side and the worker working around the coil. The length of one coil revolution is Pi-times-outside-diameter. Then after the re-roll is unrolled a measuring tape can be taped to the length every 6" to 12" and exact cut-off length marked. (A very long length of stainless-steel sheet-metal would have to be coiled on a form, pulled up on the roof, and then uncoiled.)

Additional Notes: Riveting the side-laps of the stainless-steel roofing with closed-end stainless-steel pop rivets can smooth out gaps but also provide protection from wind lift. If protrusion of the rivets against the roof deck is a problem, or if the rivets are expected to leak, then brazing of the side-laps with silver-solder might work. Now, another idea for protection from wind lift would be stainless-steel square tubes (about 1 1/4" square and 1/8" wall thickness) laying on the stainless-steel roofing and runing up the front of the roof and down the back of the roof. Then the stainless-steel square tubes would attach to each other at the ridge and attach to the faceboard (or to vertical pieces dropping to footings in the ground) at the eaves. That hold-down structure, if used, would probably be at the gable-ends and at the section end-laps. And the hold-down structure would not hold down with weight but hold down by bolted connection and sit lightly on the roof. In any case, the eave face-board course is probably a separate piece from the roof-deck course and the gable-end course is probably a separate piece from roof-deck courses overhanging the gable end.

KBH: KBH of metro Atlanta, GA is a software application developer and an inventor and designer. KBH also owns KBH Applications. Contact is through the e-mail listing on this web page.


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Last revised:
October 02, 2012 (Original)
June 17, 2014 (Current)
July 09, 2014 (Current)
July 15, 2014 (Current)