KBH Applications

The Affordable Stainless-Steel Roofing System: Most metal roofing is about 0.015 to 0.018 in thickness but formed into shapes and designed to be interlocking. Of course, steel or aluminum roofing must have advanced coatings or painting to stand up to the demands of a roof. But some metal roofing has thick plastics applied to it. However, stainless-steel roofing doesn't need coatings, painting, or plastics but just brushed finishes. Now, stainless steel can be bought wholesale from mill companies that sell to more common metal-fabricators. And so stainless-steel can be found in rolls of about 0.030 thickness or as 22 gauge to 20 gauge and that is twice as thick as most other metal roofing. The economy here is avoiding metal-fabricator middle-men and in fact avoiding any fabrication. Also, stainless-steel rolls can be found that sell to roofing manufacturers that have a designed roofing finish and that is a little more advanced than various standard mill brushed finishes. Colored stainless-steel, probably anodized, would be expensive.

Installation of the Affordable Stainless-Steel Roofing System: Roll the 0.030 stainless-steel in one piece along the roof edge near the gutter. Allow for an overhang. Drill holes in the stainless-steel and use stainless-steel wood screws (or stainless-steel nails) at the upper edge of the rolled section. Roll the second run along the roof and overlap the first run by 2" or so. Continue installing rolls up to near the ridge until a ridge roll can overlap previous rolls on both sides of the ridge. However, the roll before the ridge can be a double layer so that stainless-steel pop-rivets can attach the ridge roll to the top roll layer of the overlap. Note that this example assumes simple A-shaped roofs.

Interlocking the Affordable Stainless-Steel Roofing System: Now worry that the 0.030 stainless-steel sheets (at approximately 14" width) will rise in the wind and expose the underlying roof to horizontal direction. Also, worry about metal rattling sounds. Well, if the stainless-steel were about 0.070 in thickness and 14" width this would be no problem but with a 0.030 thickness there might be a problem in storm conditions. So to interlock the 0.030 stainless-steel sheets use a stainless-steel pop-rivet that has an enclosed bottom and these are called closed-end pop-rivets. Now these rivets can be set with a manual pop-rivet tool that is specifically designed for them. Also, the rivet should be specified for the thickness. Then rivet the leading edge of each roll installation to the roll it overlapped. Now note that the rolls before the ridge roll no longer need to be double rolls. Problems ? Well, the roof is depending on hundreds of water-tight closed-end pop-rivet connections. Of course, exposed-roofing-fasteners could be used instead of the pop-rivets but those have rubber seals and rubber has a limited life.

Additional Note for Interlocking the Affordable Stainless-Steel Roofing System: Consider roll "A" attached to the roof in one-piece at 14" width and parallel to the gutter line. The stainless-steel wood screws or stainless-steel nails for the upper edge attachment could have stainless-steel washers. Then those stainless-steel washers should have a fitted center hole but also have an outer diameter of 2". Next, roll "B" would attach to the roof while overlapping the upper edge of roll "A" by 2". Finally, the leading edge of roll "B" could rivet to the lower washer area of roll "A" without drilling into the roof covering of roll "A". Of course, advanced closed-end stainless-steel 1/8" pop-rivets are being used. (But note that a stainless-steel rectangular tab would have more reach and a more predictable shape than a stainless-steel washer.) The problem here is that the leading edge of roll "B" would inherently have a gap as the washer thickness would be about 0.060 and the leading edge of roll "B" would hold at that level rather than pull down to the roof covering. Of course, the dimensions here are for example only as this roofing system could use many other sets of dimensions.

Details of the Affordable Stainless-Steel Roofing System: The first roll installation near the gutter could have a drip shape into the gutter or it might bend and attach to a facing board that will be behind the gutter. And so a supplemental drip roll might need to be planned and installed when the first roll is installed. Also, the rolls at the gutter could be wider than the other rolls or else just have a shorter step. Of course, the stainless-steel roof is likely attached to a plywood roof deck that has an underlayment on it and the interior attic space is likely insulated. Another note, the rolls could have a downward bend at the sides of the roof. Finally, popular stainless-steel alloys are 304 and 316 . New note: Roofs near oceans should use 300 series stainless-steel. Then 304 is probably the least expensive while 309 has less thermal expansion. Roofs that only face rain water might be okay with 430 stainless-steel. Then 430 stainless-steel is less expensive than 300 series stainless-steel but also has less thermal expansion. In all cases, ordinary mill finishes are 2D as dull and 2B as bright. Metal roofs with baked-on paint or with newly developed advanced coatings are likely to lose corrosion protection anywhere they are cut or drilled. Stainless-steel on the other hand is a through-and-through alloy.

Advantages of the Affordable Stainless-Steel Roofing System: A stainless-steel roof will not rust or corrode and does not need painting. Various stainless-steel finishes are available but shiny stainless-steel finishes can be avoided. Rain water off a stainless-steel roof can be potable. The stainless-steel roof is light in weight but extremely durable. The stainless-steel roof should last as long as the underlying structure and therefor make very little demand of the homeowner or the environment. A handheld power-grinder finish could possibly be performed on a stainless-steel roof at anytime after installation.

Additional Notes: Stainless-steel in 20 gauge size weighs about 1.5 pounds-per-square-foot. With a 2" overlap on the roofing layout of 14" the weight would be about 1.7, with a 3" overlap the weight would be about 1.8, and with a 4" overlap the weight would be about 1.9 . The overlaps are necessary since roofing fabricated into interlocking shapes has been avoided. Rolls of stainless-steel are sold by mills or distributors by the weight of the roll. A metal fabricator could sell rolls by length but that would be more expensive. The previously mentioned rectangular tabs could be fabricated in the home workshop from stainless-steel sheet since they are only about 0.060 in thickness. Dissimilar metals could be a problem so all roof accessories and fasteners should be stainless-steel if they are metal. Next, consider stainless-steel finishes. A 2B finish is a dull gray and could have surface imperfections. A brushed #4 finish is shiny but heavily brushed with visible strokes. A #8 mirror finish would be too bright. The 2B finish is probably the least expensive. And there are other mill finishes available.

Additional Note Concerning a Tab Installation: Stainless-steel tabs in 0.035 thickness might be strong enough but if they are not perfectly flat then they should be installed concave-down. Then the gap at the leading edge of a riveted tab layout would not be noticeable. If stainless-steel tabs in 0.070 thickness are used then there would a noticeable gap at the leading edge but more strength. To drill into the tabs without drilling into the lower roof covering of the overlap, a depth stop can be used on the drill and also a temporary protecting sheet can be put under the end of the tab when it is installed. But the stainless-steel wood screws or stainless-steel nails could install every 16" on each roof rafter line (possibly no tab at a midpoint fastener) with the stainless-steel tabs underneath the fastener heads and on top of the roof covering. Then the overlapping roof-covering rivets only to the tabs. The tabs could be about 1.75" wide and reach the amount of the overlap. The other installation method of riveting the leading edge of roll "B" directly to the overlapped roof covering of roll "A" just runs the risk of a few imperfect watertight pop-rivets set out of several hundred set.

More Notes Concerning Installation Methods: The rivet of the leading edge of roll "B" to a tab installed with the overlapped roll "A" could have a problem of the end of the rivet protruding under the tab and making a larger gap at the leading edge of roll "B". So another technique for use of the tab would be for the tab to reach a little further than the overlap and then bend back over the leading edge of roll "B". Now this type of tab could be fabricated in the home workshop using a vise but it would be better if commercially produced. Of course the tabs are an efficient use of material. However, one problem here is that the water flow on the roof would not be as smooth. So four types of installation methods have been described with the "first" method being no-riveting except for the ridge, the "second" method being a riveting of the overlapping roll "B" directly to the underlying roll "A" with closed-end rivets, the "third" method being a riveting of the overlapping roll "B" to a tab installed with roll "A" without drilling into the roof covering of roll "A", and the "fourth" method being a tab installed with roll "A" that bends back over onto the overlapping roll "B".

Note on Thermal Expansion: The stainless-steel roofing and the roof decking that it is attached-to can have different thermal expansions. So as previously said, the stainless-steel should be drilled for the fasteners. Then the hole for the fastener could be larger than the shaft of the fastener but smaller than the head profile on the fastener. Also, the fasteners should not crimp the stainless-steel roofing but simply touch flush. And note that counter-sunk fastener heads are not being used. Then a thick-head stainless-steel wood screw might be used or a thin-head stainless-steel nail might be used but good head diameter would be an advantage. A good choice for a wood screw might be a stainless-steel truss-head type at about #8 size while a good choice for a roofing nail could be a stainless-steel 0.134" ring-shank with a 3/8" diameter flat head. But a stainless-steel roofing nail with a plastic cap is only for underlayments. A thin-head stainless-steel nail allows the overlap to lay flatter while a thick-head stainless-steel wood screw makes correct riveting more difficult at the overlap but might add profile. New note: Consider lateral elongated holes for the attachment of the stainless-steel roofing to the roof deck.

Thermal Expansion Calculation Example: The thermal expansion coefficient of 430 stainless-steel is 0.0000058 . Consider a lateral roofing layout of 70 feet and a seasonal temperature change of 110 degrees. The expected thermal expansion would be 0.0000058 x 70' x 12" x 110 or 0.54 inches. However, from a midpoint the thermal expansion would be 0.27" in each of the two lateral directions. So the fasteners of the stainless-steel roofing to the roof deck should be in lateral slots that are 0.27" long but PLUS the shaft diameter of the fastener. At 0 degrees temperature the outer fasteners should be installed at the outside edge of their slot. At 110 degrees temperature the outer fasteners should be installed at the inside edge of their slot. The remaining fastener positions would be proportioned from the midpoint with the midpoint fastener being in the center of its slot. At 55 degrees all the fasteners could install at the center of their slots. Or more likely, install all fasteners in the center of a lateral slot that is 0.54" long but again PLUS the shaft diameter of the fastener. Of course, this example covers a temperature range of 0 degrees to 110 degrees. And the thermal expansion of the roof deck itself could provide additional margin of error.

Note on Underlayments: A synthetic underlayment can be found that allows standard stainless-steel roofing nails and does not require stainless-steel nails with a plastic cap. And so this underlayment could allow the stainless-steel roofing to lay flatter. A synthetic underlayment can last a long time but it requires a lot of attic ventilation. Or an asphalt felt underlayment can be found that has a fiberglass backing for extra strength. The problem with this underlayment is simply that it is a petroleum product that rain water might touch.

Drip Edge: If a gutter is not used and additional drip edge is needed than stainless-steel sheet in .035" thickness could be added-on to the stainless-steel roofing section that attached to the eve. This attachment would be with stainless-steel closed-end pop rivets.

First New Emerging Installation Technique: One installation technique that could be considered would be the use of 20 gauge stainless-steel roofing with a 4" overlap. Then 0.070" stainless-steel tabs would be installed with the fasteners to reach the overlap. The width of the tabs could be about 1.25". Next, the overlapping roll would rivet the 0.035" thickness to the 0.070" tab using a stainless-steel pop-rivet that has a grip range of only 0.063". Then the rivet would not be set perfectly but would not protrude under the tab and should still have good holding power. In fact if the underside of the tab could have a large counterbore to about half-depth then the rivet could set perfectly. But a water-tight riveting is not the issue here since only the tab is being riveted-to. And again, the problem with this type of installation is the 0.070" gap at the overlap.

Second New Emerging Installation Technique: With this installation technique, every stainless-steel roll layout would be two layers with the combined thickness of both layers at about 0.035". The bottom layer might be less than 0.010" and the top layer might be 0.025" but not likely more than 0.030". Then the two overlapping layers would rivet to only the top layer of the overlapped roll layout. The stainless-steel closed-end pop-rivet should be watertight but if not then there is a bottom layer not riveted-to. The problem with this type of installation is that of depending on the overlap and the roof slope for water splashing not be be an issue at the riveted seam.

Third New Emerging Installation Technique: The first stainless-steel layer and the second stainless-steel layer could be separate installations. The first stainless-steel layer would be very thin and have minimum overlap and no riveting of the overlap. The second stainless-steel layer would be the thicker layer and the layer with a riveted overlap. This second layer overlap would not line-up with the first layer overlap. The second layer would only rivet to its own overlap and not rivet to the first layer. However, the second layer would still need to maintain a good amount of overlap since the overlap is covering the primary attachment to the roof deck and that through the first layer. The first layer would attach to the roof deck with widely-spaced thin-head stainless-steel nails since the first layer doesn't share its beginning attachment with the second layer. The only advantage with this installation technique is the smaller overlap of the first layer and more protection of the roof deck at the second layer overlap.

Warped Roofs: Some standing-seam metal roof systems say that they can install on open rafters. That implies that these roofing systems could install on a 16" grid of spacers on a warped roof deck. With my own testing, it seems that the roofing system described here would need an 8" grid of spacers to lay on. But the spacers could be 3 1/2" square wood, cut to height, and installed with 1/4" lag-screws that are set in a counterbore. Since the lag-screws would be covered by the stainless-steel roofing but not touching the stainless-steel then the lag-screws could be either galvanized-steel or stainless-steel. Also, lag-screws are available in the longer lengths. Or, #8 truss-head wood screws with 2 1/2" length might be set in deeper counterbores and then be less of a stress-raiser in the rafters. Now, the good places of the warped roof could have a spacer that is 3 1/2" square and 1 1/2" tall and therefor cut from a 2-by-4. Then the bad places of the warped roof could have a spacer cut to height from a 4-by-4. Finally, consider structurally replacing the warped roof before roofing begins. But now I see a source that installs standing-seam roofs on lateral 1-by-6 furring strips at every 12" center-to-center up the roof. Then if a roof had a small amount of warping, a few fender washers could go under the 1-by-6 boards and the 1-by-6's could be held down by two #8 stainless-steel wood screws in shallow counterbores and at each rafter line. A standing-seam roof would need the lateral furring strips in case the roofing panels did not hit perfectly on every rafter line but the roofing system mentioned here could just install on the grid of spacers. In fact a standing-seam roof might not install well on spacers along a severely warped roof because the spacers could be pitched at different vertical angles to each other. The roofing system described here might more easily adapt to the spacer layout. But then another warped roof technique would be 2-by-2's bridging between the high points with spacers just cut to fit under the 2-by-2's at the lower points. Then 1/4" lag-screws would be set in counterbores and attached on rafter lines. The 2-by-2's might need to be ripped from larger boards that have the required length. If the 2-by-2's were lateral then a standing seam roofing system might not have enough mounting area for clips. And lateral 2-by-2's would allow a closer spacing but to save weight I'll suggest 8" spacing center-to-center. Then the weight of the 2-by-2 furring strips combined with 24 guage metal would be about 2 pounds per square foot but that's without allowing for metal overlap. In any of the cases, the warped roof would need to be stablized with additional bracing in the attic.

Standing-Seam Metal Roof Systems: Standing-seam metal roof systems can be found in stainless-steel. Then cost might be reduced by ordering a mill finish instead of a custom finish. And cost could be reduced by ordering a drip shape instead of using a gutter. Some suppliers of standing-seam roof systems include rent of the forming machine with the order. Other suppliers offer on-site contractor guidance after delivery. But most suppliers just deliver the fabricated roofing material to experienced contractors. Then some idea of installing a standing-seam metal roof over old shingles is not a good idea. The old shingles should be pulled off to get weight off the roof. But as previously mentioned, these roofing systems are going to be more expensive because fabrication is being bought instead of just raw material. Strangely enough, there are videos on the internet where standing-seam metal panels are formed and attached to each other with hand tools. And in fact, I am working on a viewpoint of a simplified standing-seam roofing system. Of course the panels would be formed with hand tools but the cost of a handheld forming tool could approach $800. A standing-seam metal roof could deal with ice dams better than many other roofing systems.

Roofing System Note: As many details and ideas as possible are presented here so that each roof installer can develop their own installation configuration.

House Construction with Stainless-Steel Brackets

Retrofit Roof Bracing

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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