A video we shot of a metal roofing project by Hardin Construction attracted over 200,000 views. This clip shows how a roofer completes a double lock folded ridge in 26ga painted steel. The technique is seen in historical architecture and is not uncommon to last over 100 years on a building.
Below, we will address a couple of the comments related to this technique in order to better educate anyone with an interest in historically accurate metal roofing. These responses are from highly regarded Professional roofers (see end of post for info).
Video: Double Lock Standing Seam at Ridge
Comment #1: You Are Not Using a J Channel and Ridge Cap!
This roofer is accustomed to running panels near the top of the roof, screwing through the panels with a j-strip, closure strip, or z-strip, which has butyl tape adhered to the underside and then clip the ridge onto that. The downside is that screwing these z-strips directly through the panels punches the panels (i.e. leaks) but also restricts the expansion and contraction of the panel, which could cause more leaks and unnecessary stress. – Orion Jenkins of Jenkins Slate Masters
This job in particular was a historic replication of an old tin roof, a ridge cap is a dead giveaway to those who understand historic architectural details and its very important to the discerned home or property owner to look appropriate to its period. – Craig Hardin of Hardin Construction
There is no actual downside to a ridge cap other than aesthetics, if done with bread-pan folds and a locking edge instead of z strips, a traditionally constructed ridge cap is a solid detail and also provides the modern look some jobs require. A traditionally folded bread pan and cap can also be modified to include a vent.
The “downsides” of ridge caps in component systems are of course inherent in the nature of the whole systems, it’s also the downside of their valleys, roof-to-wall, protrusions or details of any kind as they rely on screws thru the pans, butyl tape, and sealant. The sealants and tapes will break down eventually and when they do, you’re locked into a replacement or repair cycle that’s only as good as those temporary products. – Kurtis Hord of HKC Roofing
Comment #2: No Ventilation?
Most homes designed pre-thermostat are intended to naturally aspirate. The attic is a cold space or a buffer between the living areas of the home. Sometimes when modernizing a historic home which naturally and passively handled air and moisture through the attic, it’s more prudent to incorporate active air handling and circulation since the walls can no longer passively alleviate the gradients. Roof venting in modern construction solves a problem created by modern construction and focus on wall and envelope insulation rather than creating a passive barrier. On an unmolested historic structure, you can replace fully seamed non-vented roofing in kind with no need for ventilation. – Kurtis of HKC Roofing
There are many other ways to vent a roof besides a ridge vent. To name a few:
Attic fan, gable vents, cupola, turbine “whirly bird”, sheet metal vents.
When using SIP panels or insulated roof decks, no venting is typically used unless utilizing built up cool roof system. – Craig of Hardin Construction
Traditional standing seam roofs can be vented at the ridge and can be vented other places (i.e. gable ends, surface vents) but don’t always need venting. The roof in the video wasn’t vented at the ridge and probably didn’t need to be. – Orion of Jenkins Slate Masters
Comment #3: Why Don’t The Panels Line Up?
This makes it easier for the roofer to make the double fold at the ridge. There’s a lot of material to fold over if they are lined up and can give the ridge a wavy appearance from the ground. On hips where the seam intersections are noticed more so from the ground they are usually offset by 1-2” to give the appearance of merging together. – Craig Hardin
You DONT want to line-up the panels when you are traditionally seaming (using the technique in the video). Imagine folding over (double locking) all that material, with seams joining from both sides of the roof, in one place! With that said, you CAN line-up the panels using different techniques or when a ridge vent is being installed. – Orion Jenkins
Panels “lining up” – also a symptom of modern metal roofing. Since they are not intersecting pans and interrupt them for z bar and cap, it’s customary and considered workmanlike to align the pan seams on either side of a hip, or ridge. In seamed work, this is the opposite because folding two intersecting seams into a double lock is very difficult and provides no added value. It is sometimes done by very good folders to “show off” essential how perfect their notching is, but generally it’s frowned upon because again it adds risk, (of folds not completing well) with no added value other than aesthetics. – Kurtis Hord
Comment #4: Yeah This Works With Copper/Zinc…Try Steel!
“Tin” you may know is a misnomer. Traditionally what we refer to as “tin” roofing was actually steel with a coating of lead/tin. The proper name of that “product” was terne metal, but again it’s a steel base with a coating.
Folansbee terneplate was 28 gauge and very light, and could be double folded on an intersection with almost no notching. The old hips I have taken apart and inspected have the full 8 layers in the fold, all the way through, meaning it’s quite possible to successfully fold 28g steel with very little pattern making skill, and site-cut your hips and ridges.
Just last week, I experimented with some 24 gauge Drexel panels and found while it takes a lot more strength in the hand to tong with the heavier gauge steel: it is actually very forgiving in hammering and stretching through a curved seam, more so than copper even. – Kurtis Hord
Every Job is Unique
Speaking to roofers all over the country on a daily basis, there are a full range of the techniques and installation methods that roofers choose. It is pretty apparent that MOST roofing professionals know what they were taught when they were younger and stick to that method.
What’s important to realize is that every job has unique circumstances based on the architectural requirements and stylistic preferences of those involved. There are projects that call for old historical methods just as there are projects that call for modern roofing methods. Metal roof warranties are a huge dictator of the method that a contractor will choose when installing.
Keep your mind open to old and new ideas and don’t be quick to discredit other methods that may be unfamiliar. Happy roofing in 2020!
Kurtis Hord of HKC Roofing
Kurtis is a traditional roofing enthusiast who is well known for managing the website www.tradroofing.org. Kurtis has worked as a trainer for various crews around the USA in European folding techniques and holds a vast array of knowledge on historical techniques.
Orion Jenkins of Jenkins Slate Masters
Orion runs a business under the name Jenkins Slate Masters and is a roofing authority. Specializing in slate and metal, Orion’s work has taken him around the world to complete some really complex projects.
Craig Hardin of Hardin Construction
Craig owns Hardin Construction in Maryland and strives to blend historical and European roofing techniques with modern day methods and material.