The upfront outlay and the long term
Metal is not one more product line among the types of shingles: it is another material. It costs more to buy, and installing it requires special tools and roofers who know it. To see the gap on your roof, have us price both materials for the same work.
An owner who stays a long time can avoid a full re-roofing with metal. One who plans to sell within a few years is less likely to get the outlay back.
Two ways of aging
Shingles wear out. The sun dries their asphalt, their granules come off, and they become brittle.
Metal ages differently. Its finish fades, and its fasteners and seams need to be checked. Over the life of a metal roof, a shingle roof is redone once, sometimes twice.
Snow that slides
On a smooth surface, snow slides. The roof carries less load, but the risk moves to the ground: a slab that breaks loose can land on an entrance, a car, a balcony or the neighbouring lot.
Snow guards are installed above doors, walkways and parking spots. Near a neighbour, settle the question in the quote.
Rain on metal
Metal is noisy on a shed, where it is screwed to strapping with nothing underneath.
On a house, metal usually rests on a solid deck and an underlayment, above an insulated attic. Rain is then much less audible.
Repairing, and living with the look
Changing three shingles is a small job. Changing a dented metal panel is less so, and matching the same colour ten years later is not guaranteed. The clean lines of metal suit some houses and clash on others.
Changing material in Laval
Laval's Code de l'urbanisme (urban planning code) allows, among other roofing materials, asphalt shingles, factory-painted and pre-baked metal, and galvanized sheet metal, standing seam, batten seam or Canadian-style.
For a residence, the City requires a permit when the roofing is replaced with a new material, and does not require one when it is replaced with the same material. From asphalt shingles to metal, the material is no longer the same: plan for the permit application. The City does not define same material, however: a less clear case goes to the Service de l'urbanisme (the City's urban planning department).
In a territory of heritage interest, or for a building of heritage interest, changing the roofing materials of a principal building goes through a PIIA (site planning and architectural integration program). The Code exempts replacement with the same material in a similar colour, replacement with a material that keeps or restores the original or traditional features, and renovating a flat roof. For a switch from shingles to metal, the City may ask for the project to go through it.
Frequently asked questions
Should metal always be preferred?
No. Metal lasts longer, but it costs more up front and its installation is specialized. For someone who will sell in the medium term, shingles still make sense.
Can metal be installed over old shingles?
Some metal systems are installed over old shingles. You then give up seeing the deck and correcting what it hides. Ask us what the manufacturer requires and what we recommend.
Which roofing lasts the longest?
Metal lasts the longest: 40 years and more, versus 15 to 30 years for asphalt shingles, according to manufacturers and the quality of the installation. On a flat roof, where neither is installed, an elastomeric membrane lasts 25 to 35 years.