Can You Lay Asphalt Shingles Over Old Ones?
The simple answer is you could add a second layer, provided the old one still forms a solid base. In fact, this might represent a saving because the foundation board is already there. We had a prospect ask us to lay new asphalt shingles over old ones the other day. However, in this case we had to decline because the old shingles were so curled.
Think Carefully Before You Lay New Asphalt Shingles Over Old Ones …
Having two layers of asphalt shingles can create problems, while not necessarily making the roof more waterproof. However, by leaving the old shingles in place you avoid a messy removal job, and possibly the need to replace the old foundation boards.
That’s said, you are presumably doing this because the old shingles are failing. If you cover them over, you can no longer monitor the situation. You also still have to replace the old vents, ridge caps and misshapen shingles, and fix any other problems you find while doing the job.
That said, you may be able to get away with laying laminate or dimensional shingles over. That’s because they’re thicker than standard shingles and their staggered edge profile may ‘work around’ any dips or high spots in the old surface.
However, if you do decide to lay new asphalt shingles over old ones you will have double trouble (and expense) the next time round because building regulations seldom allow more than two layers.
More Reasons Why You Should Think Twice About the Extra Layer
Moreover, there are several practical reasons why we advise our clients to think carefully about this option before they go a head and commit.
# We replace asphalt shingles with similar ones after the edges curl so much they start leaking
# Makers of asphalt shingles design these on the assumption they will rest against a flat surface
# If the new shingles lie on a bumpy surface then rain, wind and sleet can creep under the edges
# You don’t have the opportunity to walk-test the sheathing underlay for sponginess suggesting rotting
# A double layer of asphalt shingles can add an extra 400 pounds of weight to your roof timbers
Valiant Exteriors is here to serve the Calgary community by helping keep their homes waterproof and weather-tight. Please call (403)829-1661 for a quote if your insurance has given the go ahead to lay new asphalt shingles over old. We’ll be delighted to assist with a competitive quote, a competent job and brilliant after-sale service.