Roofing Materials

Roofs are composed of many different materials but, broadly speaking, there are four main components common to the structure of most roof systems: a lumber framework (shown on the previous pages), felt underlay, a roof covering, and flashing (waterproofing at joints). The options in these four areas are shown and explained here, along with some supplementary items used with the materials shown. You may find it helpful to also read this.

FASTENERS

The specifications for fasteners such as nails and /or screws used in roof construction can vary according to local building regulations. Coated and galvanized nails are often used. They provide the best protection, because they are anticorrosive. The most commonly used are called roofing nails.

ROOF COVERINGS

Seek advice from manufacturers when deciding how to install tiles or shingles on a roof. Although it may seem easy to replace like with like, newer regulations may require a different method. If you are planning a new roof, the installation method will be influenced by the pitch of roof, chosen tile type, and prevailing weather conditions. For example, some tiles hook over furring strips that help hold tiles in place. However, in an area prone to driving winds, it may be necessary to nail down some or all of the tiles. Special tiles for ridges and hips are usually secured with mortar, as are verge details. However, many new properties have ridges, hips, and verges finished using waterproof gaskets and screws.

 

Shingles

Most popular. Wooden shakes are similar to shingles, but are handmade so have a rougher appearance.

Wooden Shingle: Machine-sown for smoothness; Usually cedar or redwood.

Asphalt Shingles: May be reinforced with fiberglass for strength and fire resistance; Come in sheets of several shingles

Concrete tiles

Mimic clay designs and are made to interlock easily. Plain Tile; Pan Tile; Roman Tile

Clay tiles

Give a traditional look, but cost more than concrete. PLAIN TILE: Double lap tile: nibs are at rear; PAN TILE: Interlocking .single-lap tile; ROMAN TILE: Interlocking single-lap tile; Ridges align all the way down the roof.

Slate tiles

Strong and durable, slate provides long- lasting roofing and is more lightweight than other tiles. Cheaper synthetic slates are another option. SYNTHETIC SLATE TILE; NATURAL SLATE TILE

Specialty tiles

Tile manufacturers now produce tiles shaped specially to finish different roof details.

Cloaked verge tiles: These lap over the edge of a gable to finish the roof line neatly, and eliminate the need for any mortar to finish the verge.

Hip tile and hip iron: Also known as bonnets, hip tiles are placed along the hip of a roof. Ridge tiles can be used instead, with a hip iron at the eaves to support them.

Valley tile: Shaped tile used in valleys in place of a flashing system.

Ridge tile: Arched tile used to cover a ridge. May also be used along a hip, depending on the roof design.

ROOFING FELT

For a small repair, choose felt to match what is already on the roof. If you need to lay new felt, think about whether you need it to be breathable -- for instance, because the roof space is insulated and /or ventilated in a particular way.

Breathable felt: Allows moisture inside the roof to escape, but prevents moisture that's outside from getting in.

Bitumen-reinforced felt: A very effective waterproof barrier.

Plastic “felt”: Alternative to bitumen- reinforced felt. Both types are non-breathable.

STRAPS AND PLATES

Metal straps and plates are used to hold lumber together in roof structures -- especially in modern trusses. These types of joints and plates make installation much more straightforward, as there is no need to cut complex wooden joints. Since roof structures have so many joints, they can be a considerable timesaver.

Restraint strap: There are several designs of restraint straps made for various uses and roof types. The example shown here fits across the end rafters next to a gable and attaches to the wall.

Timber connector: Used at joints in trusses to hold together roof parts.

Truss clip: Used to connect trusses to a wall plate.

Heavy-duty truss hanger: More robust.

FLASHING TOOLS AND MATERIALS

The waterproofing materials used in valleys, abutments, around chimneys, or at any other joint between different parts of a roof -- are known as flashing. Metal flashings such as tin and lead are the most traditional type, and are still widely used despite modern alternatives.

Lead flashing: A traditional flashing material, lead is hardwearing, waterproof, and malleable, so it can be easily molded into the desired profile.

Self-adhesive flashing repair: Applied over damaged flashing for a repair. Primer may be needed before application.

Glass-reinforced polyester (GRP): GRP flashing is now commonly used as an alternative to lead flashing for valleys and abutments.

Lead dresser: For shaping lead along abutments and over different shaped tile profiles. Has curved and flat faces to suit all roof shapes.

VENTILATION MATERIALS

Poor ventilation in a roof is a major cause of mold. There are a number of different options for ventilating a roof. Ridge and tile vents can be joined with ducting to waste pipes or devices such as a bathroom exhaust fan, but they must not be used instead of a flue for extracting hot combustion gases unless this use is specified by the manufacturer. Insulating a roof is discussed in detail here.

Tile vent: These tiles have an integrated vent. They are often plastic, and need to be installed with an underlay seal.

Ridge vent: Offer direct ventilation channels through the ridge. This may be as part of ridge-tile structure (as shown here), or in the form of channels that are installed along the lower edge of the tiles as they are laid in place.

Fascia vent: Clips onto fascia. The channels in the lower section allow for airflow through fascia and into loft space. Vent at front of lower section; Channels lower section.

Monday, December 26, 2016 8:11 PST