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.

Final Notes: If the stainless-steel sheet-metal is handled perfectly then it lays very flat at the side laps. It doesn't lay as well at the gable-ends or at the section end-laps. But the side-laps at the gable-ends can be riveted with stainless-steel closed-end pop-rivets such that if a few leaked they would just leak to the ground. Then the section end-laps are two layers of course but the side-laps of the section end-laps are four layers. And so the side-laps of the section end-laps can be bolted with an upside-down stainless-steel bolt in a lateral slot by not using the bottom layer. This leaks to the bottom layer so that the very edge of the side-lap must be used and the very end of the end-lap must be used. Now also the ridge piece can reach down to the first side-lap that is near the ridge and it can be riveted to the side-lap by not using the underneath layer. Here the only problem is the protrusion of the rivet against the underneath layer. So the rivet can be tested as to how many stainless-steel washers can be used under its head and still have a good hold. That reduces the protrusion of the rivet. Or an upside-down stainless-steel bolt could be used and leak to the underneath layer of the sidelap. Continuing with more notes, a stainless-steel cleat of 0.07" to 0.10" thickness can be installed under the stainless-steel course at the eave and then the course at the eave can fold over the cleat for hold at that point. Now handheld roller tools can make a 90 degree bend on a long piece of sheet-metal and also a second operation can take that bend to near 180 degrees to make a shape to slide on the cleat. At this point, the previous idea of sliding clips at the eave are not needed and those did not work very well in practice anyway. Also, the roof design might decide not to use the previously mentioned over-the-roof hold-down structure. And consider not having section end-laps at all but just the more difficult handling of longer courses of sheet metal. Another note, since the courses at the gable-ends can be held together with a rivet then then they might work okay with a folded-over or rolled end. But finally, don't forget about the possibility of using coils of stainless-steel sheet-metal with a standing-seam roofing system. The only disadvantages with a standing-seam roofing system are that roofing panels must be formed and that the roofing panels will not conform as well to spacers on a warped roof.

Final Tool Note: Affordable straight sheet-metal brakes can be found in four-foot and six-foot lengths. These metal brakes can make ridge pieces of four to six feet long and can make face-board drip-edges of four to six feet long. Now, pieces of sheet metal to be bent at the halfway point of their length, and attached only at their length ends, should be flattened sheet metal.

Continuing Notes: A hip on a roof works just like a ridge (except for intersection of layout versus alignment of layout). Flattened stainless-steel sheet-metal must be bent to the correct angle and reach to make sides of the hip run. Then the hip pieces attach to the top layers of the roof-course side-laps with upside-down stainless-steel bolts and attach at the edges of the side-laps so that the lower layers of the side-laps catch the leaks. Or a roof valley must have flattened stainless-steel sheet-metal bent to the correct shape and reaching to make sides of the valley run. But the valley pieces need 2" high sides or so. Then the roof courses must be built-up underneath to rise up to the height of the valley-piece sides and overlap the valley-piece sides by several inches. Of course, ridge pieces, hip pieces, and valley pieces all make end-laps with themselves relative to their direction of installation. But roofs with hips may not have the problem of gable-ends. The gable-ends will be better held with the over-the-roof hold-downs. The eaves will be better held by having the eave courses folded over onto a 0.07" to 0.10" stainless-steel cleat. Gable-ends, hip intersections, and valley intersections are the most likely spots for roof gaps larger than 1/8". But if a bug touches the stainless-steel roofing on a hot day then it might not come back.

Additional Note on Roof Valley Layout: The previous note on roof valley layout might work best in a situation where the roof courses run up to a vertical roof side. For a roof valley that makes a strong "V" shape, consider attaching flattened stainless-steel sheet-metal, bent to correct angle, in the valley with the valley-piece reaching 12" or so on each side of center. Then the roof courses attach at the edge of the valley-pieces and overlap into the valley by a couple of inches. Now, the ridge pieces, the hip pieces, and the valley pieces are additional expense because of the amount of overlapping material and because flattened stainless-steel is used to make the pieces.

New Note: The idea arises of folding the courses at the gable ends over a stainless-steel cleat and riveting the fit tightly together with stainless-steel closed-end pop-rivets. The riveting, of course, overhangs the ground. This idea is similar to folding the eave courses over a stainless-steel cleat at the eave but that location would be expected to have a good fit. As previously mentioned, there are handheld roller tools that make a 90 degree bend on a long sheet of sheet metal and then take that bend to near 180 degrees. The difficulty is in handling the material without kinking it as it needs to be on its back when the edge is rolled. In comparison, the over-the-roof-hold-downs hold at the eaves, at the gable ends, and near the ridge but only hold at the over-the-roof run locations.

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)
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