Cedar Shake and Shingle Roofs

Shake or shingle, and why it matters

People use both words for the same roof and they are not the same thing. A cedar shake is split, so the face is rough and the thickness varies, and it sheds water fast. A cedar shingle is sawn, so it is smooth, thinner and laid tighter.

Shakes last longer in this climate and need more ventilation under them. Shingles look neater and go brittle sooner. If someone quoting your roof uses the words interchangeably, that tells you something.

What kills cedar roofs here

• Moss, first and worst. Cedar is organic and this is a rainforest. Moss holds water against the wood, the wood stays wet, and wet wood rots. A cedar roof under cedars on a north slope is the worst case in the valley.
• No ventilation underneath. Cedar has to dry from both sides. Nailed straight to solid sheathing with no air gap, it stays damp underneath long after the surface has dried, and it fails from the back.
• Cupping and splitting. Years of wet and dry cycling curls the edges up. A cupped shake holds water instead of shedding it, which accelerates everything else.
• Rusted or wrong fasteners. Cedar's natural oils eat ordinary nails. Where a previous roofer used the cheap ones, the shakes start sliding even though the wood is sound.
• Pressure washing. Somebody's well meant cleaning, years ago, which tore the soft summer wood out from between the grain and took a decade off the roof in a morning.

Restore it, or change it

This is the real decision, and the honest answer depends on what is under the moss.

Worth keeping when the shakes are mostly sound, the cupping is light, the fasteners are holding and the problem is surface growth plus a scatter of broken pieces. Cleaned gently, the broken ones swapped, the ventilation sorted and zinc fitted at the ridge, a cedar roof with life left in it will give you a good while more.

Finished when you can push a screwdriver into the shakes, when they are thin and silver all through rather than just on the surface, when a large share are cupped or split, or when the sheathing underneath has gone soft. At that point every repair is money spent on a roof that is leaving, and we would rather tell you than keep taking repair calls.

Most cedar roofs we look at in this valley are in the second group. That is not a sales line, it is arithmetic: a roof built in the eighties has had forty winters.

What a cedar roof usually becomes

When cedar comes off, it is normally replaced with asphalt or with metal, and both are a genuine step up in service life here.

• Asphalt is the common choice: far cheaper, and a modern architectural shingle in a weathered grey or brown keeps a good deal of the look from the street. The published range is on the roof replacement page.
• Metal costs more and lasts longest, and it does not care about moss at all, which in this valley is worth something. See metal roofing.

One thing worth knowing before you budget: cedar was often laid on spaced strapping rather than solid sheathing, because it needed the air. Asphalt and most metal need a solid deck, so converting usually means sheathing the whole roof. That is real work and real cost, and it belongs in the quote at the start rather than appearing as a change order once the old roof is off. We will tell you which you have before you commit.

Keeping the one you have

If your cedar roof is worth keeping, the thing that extends it most is keeping it dry: moss off, gently, and something at the ridge to stop it coming back. Our moss removal page covers how that is done without wrecking the wood, and the short version for cedar is the same as for everything else: never a pressure washer.

Start with a look

The inspection is free, including the one where we tell you the roof has another decade in it and you do not need us yet. We get up, photograph what is there, and give you the restore or replace answer with the evidence attached.

Kory and Johnny Peters are Red Seal Journeyman Boilermakers and members of Local 280. Fraser Roofing Ltd. is registered and in good standing with WorkSafeBC, account 201893485, and carries $2,000,000 commercial general liability through HUB International. Our work carries a 10 year labour warranty. We cover Chilliwack, Sardis, Cultus Lake, Rosedale, Agassiz, Harrison Hot Springs, Hope, Yale, Mission and Abbotsford.