Wood Roofing 101

There may be fewer wood roofs around today than there were during colonial times, but there are plenty of excellent reasons why they have yet to drop off the radar completely. In this e-book, we will explore the different types of wood roofs, how they are installed, and the many things that set wood roofs apart.

PART ONE: MATERIALS AND TYPES Wood roofs come in two primary formats: SHAKES and SHINGLES. But what’s the difference between the two? That would’ve been easy to answer, say, 50 years ago, when wood shingles were sawn from a block, while wood shakes were hand-split along a block’s natural grain using a mallet and froe.

Today, modern shakes and shingles are machine-made so the sawn vs. split distinction no longer applies. The main differences between the two now lie in their dimensions and milling.

Shakes are thicker at the butt end, often 1/2 to 3/4 inch or greater, while shingles have uniform thicknesses, usually ranging from 3/8 to 1/2 inch. Shingles are also milled more precisely and lay flat when installed, while shakes are more rustic and irregular.

PART ONE: MATERIALS AND TYPES Both shakes and shingles can be made from these common wood types:

WESTERN RED CEDAR

Considered one of the most renewable and sustainable roofing materials in the world, western red cedar has a low carbon footprint—a big plus for eco-conscious homeowners.

Cedar contains a natural preservative that gives it outstanding durability and dimensional stability, but it can also be treated with linseed oil or with specially engineered preservatives that boost its performance without affecting the natural beauty of the wood.

Other benefits include a natural resistance to the elements, a high R-value (up to 4 times that of fiber cement!), and a life expectancy of 50 years or longer.

CYPRESS

Cypress shakes and shingles are known for their impressive life span. Some of the original cypress shingles on the “fishscale” roof of George Washington’s famous Mount Vernon mansion are over 250 years old and still in good shape.

Made from sapwood or heartwood, cypress shakes and shingles contain a natural oil called cypresseine, which makes them resistant to insects and rot. Cypress roofs change color as they age, a fact that only adds to their beauty.

PART ONE: MATERIALS AND TYPES

PINE

Most commonly seen on Scandinavian and Central European roofs, pine shakes and shingles are manufactured from southern yellow pine. Pine is highly renewable and, once pressure-treated, is incredibly durable. It is used extensively in home construction across the U.S. because of its ability to withstand inclement weather.

REDWOOD

Redwood offers an excellent combination of physical properties that make it especially suitable for roofing. It is lightweight but dimensionally stable and not at all prone to checking or splitting. Heartwood grades, in particular, have such outstanding moisture and rot resistance that they can be used in ground-level applications.

Redwood shakes and shingles are also known for their high thermal insulation capacities, pest resistance, easy maintenance, and distinctive deep reddish-brown color. ......

Each type of wood used in roofing comes with its share of strengths and limitations. What will ultimately determine the performance of a wood roof—for the first few decades, at least—is how well it was put together. In Part Two, we’ll take a look at some of the basic installation considerations for wood roofs.

PART TWO: CONSTRUCTION AND INSTALLATION There’s more to a working wood roof than just shakes and shingles. Like all steep-slope roof systems, wood roofs consist of the following basic components: Roof Covering Roof Structure

Fasteners

Flashing

Drainage

Deck or sheathing

Underlayment

1. Roof structure – primary roof support; consists of the rafters and trusses holding up the deck or sheathing 2. Deck or sheathing – primary roof covering; usually exteriorgrade plywood or oriented strand board (OSB); can be solid (continuous) or skip (open) Skip sheathing is preferred in wood roof systems because it allows the shakes or shingles to breathe. The National Roofing Contractors Association (NRCA) also offers the following guidelines: • plywood – at least 1/2-inch nominal thickness for 16inch rafter spacings and 5/8 nominal thickness for 24inch rafter spacings

• OSB – at least 1/2-inch nominal thickness for 16-inch rafter spacings

PART TWO: CONSTRUCTION AND INSTALLATION 3. Underlayment – secondary sheathing protection; usually a sheet of asphalt-saturated material Type I and II (formerly Type 15 and 30) asphalt-saturated, nonperforated organic felts are recommended for wood shakes and shingles. Ice dam protection membranes are further recommended in places where the average temperature in January drops to 30° or lower.

4. Roof covering – primary sheathing protection; wood shakes or shingles (see Part One) 5. Fasteners – protection against wind uplift and pull-through; can be nails or staples Fasteners used on wood shakes and shingles must be noncorroding. Galvanized steel and stainless steel nails are highly preferred. Each shake or shingle must be fastened using at least 2 nails that penetrate at least 3/4 inch into the plywood or OSB deck.

6. Flashing – protection against water seepage; usually sheet metal Wood roof systems have four types of flashing:

• perimeter edge metal

• penetration flashing

• valley flashing

• vertical surface flashing – sub-types: apron, step,

cricket (backer), counterflashing

PART TWO: CONSTRUCTION AND INSTALLATION Ideal roof flashing is 26-gauge corrosion-resistant sheet metal.

Galvanized steel or painted aluminum may be used on wood roofs, but never copper in conjunction with red cedar roofs.

This is because soluble tannins from red cedar can damage copper flashing and shorten its lifespan.

7. Drainage – protection against water seepage; a function of roof design (shape, slope, layout) NRCA strongly recommends against the use of wood shakes and shingles on roof slopes less than 4:12 (18 degrees). ......

Wood roof construction and installation can certainly get complicated. But are wood roofs even worth it? In Part Three, we’ll discuss the advantages wood shakes and shingles offer over other types of roofing materials.

PART THREE: WOOD ROOF BENEFITS Wood roofs don’t have the lion’s share of the market, nor are they the fastest-growing segment at present. Those honors belong to asphalt shingle and tile roofs, respectively. But while wood roofs aren’t as popular as they used to be, their staying power can’t be beat, and with good reasons:

Reason #1: Natural beauty While it’s true that curb appeal isn’t the number one priority in roofing, it can nevertheless tip the scale for or against a roofing material when all other major factors are comparable.

And when it comes to curb appeal, wood delivers way more than your money’s worth and does it with effortless panache.

Red cedar, cypress, pine, and redwood have a natural beauty independent of machine-made textures and baked-on paints and finishes. They contain natural preservatives that save them from the necessity of retouching over time, although some basic treatments can be used to prolong their beauty and enhance their performance.

Reason #2: Timeless appeal Put simply, wood roofs never go out of style, and not just in the context of colonial-style homes and restored historic buildings. They suit a vast range of architectural styles, which is part of the reason why other roofing materials are put through so many processes just so they can mimic the look of wood.

Wood roofs are also timeless in the sense that they age gracefully—a feat that can only be said truly of two other roofing materials: copper and slate, both of which have significantly higher price points.

Reason #3: Short production time With the exception of natural stone, wood is the roofing material that goes through the least amount of alterations from raw material to its final usable form. And even then stone suffers by comparison because of the time- and energy-intensive nature of quarrying and the difficulty in transporting the material itself. Fewer production stages to get wood from lumber to shake and shingle form means shorter production times.

Reason #4: Sustainability and eco-friendliness Wood shakes and shingles are manufactured from one sustainable, renewable raw material: wood. Both production and disposal processes are cheap, consume little energy, and release even less harmful emissions. Replanting in sustainable forests reduces wood roofs’ carbon footprint even further.

But for all their advantages, wood roofs do have their limitations. They require plenty of care during installation as well as regular maintenance. If you’re interested in wood roofs, make sure you work with a licensed contractor with extensive experience with this type of roofing system. That way, you can enjoy your roof for a long time and make the most of your investment.

PATRIOT ROOFING 1623 Stone Drive NW Gig Harbor, WA, 98335 (253) 265-6868 (253) 448-8222 Patriotroofing.biz