Frequently Asked Questions

Q. What is a purlin and what does the purlin system do?

A purlin is a roof framing member which is installed perpendicular to rafters. Traditionally purlins were used in heavy timber framing but have been replaced by plywood sheathing in most modern houses. We use true 1x4s (actually 1”x4”) installed directly on top of the existing shingles and spaced at 24” as seen below.

The purlin system (and installing on top of old shingles) has 3 major benefits: Insulation/airflow, strength and sustainability. By installing purlins on top of shingles we keep a lot of waste out of the landfill and we are able to recycle our metal scraps (and the roof can be recycled 40+ years later too!). Purlins add strength to the existing roof and can also be shimmed to visually eliminate sagging sections of old roofs. Finally (and most important) By installing the purlins and then metal we create an air gap that allows the metal to act as a radiant heat barrier. The ribs in the metal also act as natural vents, allowing hot air to flow up and out at the ridge vent, drastically reducing attic heat in the summer while retaining some heat in that air pocket in the winter!

Q. Are metal roofs noisy in the rain?

It depends, but most of the time, no. Most people say they can't tell much of a difference from their old shingle roof, mainly because attic insulation and our purlin system tends to dampen the noise. It is subjective, but often rain on a skylight is louder than rain on a metal roof. Often the idea of metal roofs being loud comes from historic houses where the metal was installed over rough sawn boards that had large gaps allowing sound to translate from the roof into the house. Modern houses have plywood roof decks with no gaps and more insulation which deadens the sounds of the elements.

Q. Can you walk on metal roofs?

Yes and no. If the metal is wet at all or has any debris, walking on the roof is extremely dangerous You can loose traction very quickly. But if it's dry and you're wearing tennis shoes, the metal is perfectly walkable, whether it was installed flat to the deck or suspended on purlins. If walking on a metal roof it is advisable to walk on the screw heads as this is directly above the supporting substrate and adds a little extra grip. NOTE: Higher pitched roofs require additional safety measures.

Q. Will my metal roof color fade over time?

There are two major types of paint used on Metal panels. The first, Siliconized Polyester is the cheaper of the two, and you guessed it, a lesser quality finish displaying severe fading within the first 5 years. We've been installing a Kynar painted panel as our standard finish for years now because it's the best finish available on the market. Kynar's color retention is distinctly superior, maintaining its rich luster well into its lifespan of 35-40 years.

Q. What are striations on standing seam panels?

With standing seam panels there are two options that primarily affects looks. Striations are vertical structures put into standing seam panels to allow for expansion and contraction (caused by heat and cold) to be absorbed into those vertical structures.

Standing seam panels without striations are a lot cleaner looking (see Materials) but face the change of oil-canning, essentially presenting a slightly wrinkled look.

Long story short, striations often help prevent oil canning/wrinkles in standing seam. There is no price difference between one or the other and if, on the off chance, wrinkles do appear they will be purely visual and will not affect the performance of your roof.

Q. What about the placement of the screws?

For exposed fastener applications like our AG Panel on purlins (see Materials), the 2 inch long screws we use have a 1/4 inch diameter head with a protected rubber washer so that all screws are watertight. At RoofCrafters, we measure and place each and every screw carefully so that the screws high up on the ribbed portion of the panel instead of the flat, allowing water to quickly run down and away from the screw.

Q. What about leaving the old shingles on when converting to Metal?

Part of the beauty of the cover system is that your home's original covering remains in place and out of the landfill. Locked between the plywood, the 1" x 4" pine purlins and the metal, the old shingles stop degrading because they are now protected from the sun, wind and rain, and become a useful vapor barrier between the plywood sheathing and the new metal. Access to, and view of the old shingles is sealed off by comprehensive flashing. Ultimately, old shingles, nails and debris stay out of your gutters and  driveway—and you save money on extra labor for removal. However, Fire Code requires removal if there are 2 or more layers of shingles. Also, if there is known damage from extensive leaking, it's better to dig up that area and repair the plywood. Lastly, if you're not comfortable with the cover system—no problem—we'll strip the shingles!

Q. Will my metal roof interfere with cell phone signal?

While largely unlikely it all depends on the current signal strength of your provider in your area. Some weaker cell phone signals may be affected by a metal roof. If you in an area with poor service, we recommend installing a signal booster, also known as a repeater, preferably a dual band repeater with a separate onmi-directional antenna.