Do We Put New Shingles Over Old?

The short answer is no, we do not put new shingles over old asphalt ones in Calgary, unless there are exceptional circumstances. But please stay with us for a while longer, and read on. We would like to share some important facts with you first, so you know what you could be letting yourself into.

Why Do Some Home Owners Fit New Shingles Over Old?

The most likely reason is they are hoping to save money, which they may probably do in the short term. You see, removing the old shingles is a time-consuming affair, and we have to recover the cost to stay in business.

But there’s also the possibility there may decaying timber beneath, which we must replace before it deteriorates further. Your home is probably your biggest investment, and our business ethics require we protect your interests.

Are There Any Insurance Advisories Against This?

Your building insurance will require that you act responsibly as building owner. The Alberta Roofing Contractors Association has this to say on the matter:

  • Asphalt shingles must be laid down over wooden sheathing with ventilated space beneath it.
  • Fitting new asphalt shingles over old ones is illegal. The old material must be removed first.
  • Existing sheathing must be inspected, and any deterioration repaired before continuing.

Why Are We Against Fitting New Shingles Over Old?

Asphalt shingles begin to crack as they age, and the edges curl up due to their drying out. This is why there is a large body of opinion against shingling over old ones that are weathered, warped, or bending up.

Moreover, it is no accident that the Alberta Roofing Contractors Association recommends laying new shingles over flat board sheathing. Put simply, moisture will leak through the outer layer of a shingle roof if the tiles do not overlap smoothly.

Chances You Take If You Go Against This Advice

You can’t properly gauge the condition of your roof, if it is covered over with old shingles. However, you can probably assume there has been some water penetration, if you delayed taking action until the edges started curling up.

Choosing not to lay new shingles over old, simply means doing a thorough job properly, and knowing your roof is secure as the rain pounds down, or the snow packs tightly on the surface.

Speak to your friendly Calgary roofing contractors, Valiant Exteriors, if you would like further advice on your roofing, eaves trough, or siding project. Remember, there’s no obligation when our specialist calls to inspect, and we’ll quote to do a decent job without cutting corners.

More Information

Canada’s National Building Code Unpacked

Why Proper Roof Drainage Really Matters

Old Asphalt Shingles: D Mahalko BY CC 3.0