Cedar shake roofs in Potomac and Bethesda, done the way cedar actually lasts.

Shakes and shingles are not the same product

Cedar shakes are split, so they have a thick butt and an irregular face, and they read as texture from the street. Cedar shingles are sawn on both sides, thinner, and lie flat and uniform. Shakes are what most of the larger Potomac and Chevy Chase houses were built with, and they are what people mean when they say a cedar roof.

Grade matters more than either. Grade 1, sometimes labelled Blue Label, is 100% heartwood, 100% clear and 100% edge grain — that is the grade a roof is supposed to get. Lower grades carry sapwood and flat grain, which is where cupping and early splitting come from. When a cedar roof fails in fifteen years instead of thirty, the grade and the fasteners are usually why, not the weather.

The three things that decide how long it lasts

1. The deck has to breathe

Cedar is a natural product that takes on and gives off moisture. Laid straight onto solid plywood with no air path underneath, the underside stays wet after every storm and the shakes rot from below while the tops still look fine. Traditionally that was solved with spaced sheathing — boards with gaps. On a modern deck it is solved with a ventilated underlayment mat or battens over the sheathing. Either way there has to be a gap, and we will show you which one your roof has.

2. The fasteners have to be stainless

Cedar is acidic. Electro-galvanized nails corrode in contact with it, and when the fasteners go the shakes slide whatever condition the wood is in. Stainless steel is the fastener for a cedar roof. This is the single most common corner cut we find on cedar roofs in this county, and it is invisible from the ground.

3. Exposure and keyways

How much of each shake is left exposed to the weather, and how the gaps between shakes in one course line up against the course below, is what keeps water moving over the roof instead of into it. Those are set by the manufacturer's instructions for the length and grade being installed.

What cedar costs you after installation, honestly

A cedar roof is not a finish-and-forget roof. It needs the debris kept off it, it needs the tree canopy above it kept back, and in shaded, damp exposures it will grow moss that holds water against the wood. Left alone under heavy shade, a cedar roof in Montgomery County will not reach the life it would reach in the open.

Fire rating is the other thing worth knowing before you commit. Untreated cedar is a Class C roof covering. Pressure-impregnated fire-treated cedar reaches higher ratings, and on some properties and in some insurance conversations that difference matters. We price both so you are choosing, not discovering.

When we will tell you not to buy cedar

If the house is deeply shaded, if nobody is going to maintain it, or if the budget only reaches cedar by cutting the deck work and the fasteners, cedar is the wrong purchase. Synthetic composite shakes carry the look with none of the moisture behaviour, and a heavy architectural shingle costs a fraction and lasts. We will quote cedar properly and quote the alternative beside it, and you can decide with both numbers in front of you.

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