roofing components Archives | Page 3 of 3

Blackridge Elementary features LokSeam

In my previous post, I talked about the important process of selecting the right materials and appurtenances for your standing seam roof system and how they should be used together for the best result. There are three more parts of the standing seam roof system that, if used, must be carefully specified.

Pipe Penetrations. Plumbing vents, heater flues, exhaust fans and pipe supports for equipment racks are all typical penetrations seen on metal roofs. Always specify rubber roof jacks for these penetrations, and use high temperature silicone rubber roof jacks on pipes that will be hot. Do not allow the use of residential type roof jacks, such as those made of plastic or lead, or the EPDM roof jacks made for single ply roofs.

Use pipe instead of square tubing to penetrate the roof when designing an equipment rack for rooftop equipment. Otherwise, there will be no good way to seal it to the roof. Pipe penetrations should always penetrate the roof in the middle, or flat part, of the panel, not through the seam itself. Ignore this advice, and you’ll probably have a roof leak on your hands.

Large diameter pipes may restrict the drainage of water. A good rule of thumb is to ensure that the base of the roof jack fits completely in the pan of the roof panel. If it will not fit, install a stack flashing in the roof at the proper location and attach the roof jack in the stack flashing. Stack flashings install into a roof just like a roof curb, but they are flat in the middle and don’t have the opening a curb does. This provides a large flat area in which to install the roof jack with room for water drainage.

Crickets. The roof design may at times require a cricket be installed to divert water around a parapet wall. And if the specifications or architectural drawings are not clear as to the proper treatment of this area, the roofer will make the cricket out of sheet metal. However, crickets should always be made out of welded aluminum or stainless steel. This allows you to have a cricket that fits and leaves no pinholes or laps that are sealed with caulk. Sunlight will eventually break down exposed caulk and may cause a leak. But when properly built and installed, a welded cricket will perform throughout the lifetime of the roof.

Snow Retention Devices. When these devices are required on a standing seam roof, never use a through-fastened device. When through-fastened devices are used, they are either installed into the secondary structural, which prevents the roof from floating, or they are installed into the roof panels only, which makes for a very weak connection that will eventually work loose, leaving holes in the roof.

The best snow retention devices utilize a clamp that locks onto the panel seam and does not perforate the roof membrane.

Keep in mind that if snow conditions are severe enough to warrant retention devices at the eave, you will also need to protect pipe penetrations as well. Many unprotected plumbing vents are broken at the roof surface from moving ice and snow.

Remember, the roof system is called a system for a reason. For a successful roof installation, all rooftop accessories should be considered. Well defined specifications and details should be provided and adhered to so everyone involved in the project knows what is expected and can bid the project accordingly.

The roof installation process will be more efficient, leak problems will be avoided and the “final inspection” will be painless. Who doesn’t want that? The end result will be a total roof system that looks good and performs well for decades to come.

The architect, roof manufacturer and roof construction installer are parts of a team that can work together like a well-oiled machine to get the best result – a professionally installed roof that looks beautiful and will last for decades.

I now invite you to think of your metal roofing system as a “team” in the sense that all parts must work effectively and efficiently together like pieces of a puzzle to function optimally as designed. A well-thought-out process puts the right combination of materials together in the right way to produce an optimum roofing system.

The process requires identifying a reputable manufacturer of standing seam roofs – one that meets your specific performance and aesthetic needs, and that provides the required warranties. Once chosen, the designer may think, “Voila! Mission complete,” when in fact, the process is just beginning.

Mitchelle Elementary School features BattenLok HS and LokSeam

Since metal roofs are being used in increasingly more complicated designs, the roof panels and related accessories that attach the roof to the substructure are a part of the total roof system. The added roof curbs, pipe penetrations, crickets, snow retention devices and lightning protection equipment all become part of the standing seam roof system. And it really matters how each of these items attach to the roof. Though it sounds logical to do so, don’t leave it up to the roofer or another tradesperson to decide how these items will be installed.

Take control and make sure the following are adhered to when specifying a standing seam metal roof system:

Do not use dissimilar materials.

Copper, lead and graphite can all cause galvanic corrosion. Even water dripping from these materials onto the roof can cause it to corrode. And manufacturers’ warranties are often void if this situation exists.

Some examples: Copper lightning arresting equipment is a typical use of dissimilar material found on Galvalume roots. Use aluminum instead. Lead hats are often found on Galvalume roots. Rubber jacks can be substituted.

Compile a qualified list of acceptable curb manufacturers. Choose only those that use aluminum or stainless steel. Many curb companies use Galvalume, which seems reasonable since most standing seam panels are made from this material. But when Galvalume-coated steel is welded, the Galvalume-coating melts at the weld. Even when a coating of corrosion inhibitor is used, it will never be as good as the uncontaminated Galvalume coating.

You also want a curb manufacturer that offers a weathertightness warranty if required for the roof. Roof manufacturers will generally warrant the attachment of the roof curb to their roof panels, but it’s up to the roof curb manufacturer to warrant the construction and performance of their product.

Be careful with roof curbs. First off, they should be “shingled” into the roof. This way, all laps shed water as it drains from the roof. Curbs that lap on top of the roof panels on the upslope side will cause problems.

Roof curbs must allow plenty of room for water to drain around them without building up a waterhead at the upslope end. Provide clearance on both sides of the curb and a long flange on the upslope end so the roof panels can lap onto the flange and maintain a 12” upslope from the top of the water diverter built into the curb.

Finally, if AC units will be placed on the roof, include PVC condensate lines to carry the water off of the roof. Never allow the condensate to drain directly onto the roof. The dissolved copper ions which will cause galvanic corrosion of the roof panels.

This is a lot to consider, possibly more than you thought was involved. Well friends, there’s even more. I’ll explore this even further in my next post.

In the meantime, learn more about MBCI’s rigorously-tested, standing seam metal roof systems and how it’s one of the most durable and weathertight roof systems available in the industry.

Tag: roofing components

The Right Team Holds Your Standing Seam Roof System Together – Part 2

The Right Team Holds Your Standing Seam Roof System Together – Part 1