Roof Framing & Lining

About Roof Framing and Lining

The purpose of roof framing and lining is to provide structural support and protection. The frame ranges between the walls of the building and carries the roof covering. Most roof designs include a slope of a pitch to allow rainwater to run off so that it could be collected and drained away from the building. The roof framing also assists in strengthening the structure against elements and wind forces.

Roofs are often constructed from timber, especially in residential architecture. However, other options such as steel or concrete are also popular and come in many different styles.

Elements & Types of Roof Framing 

Roof Rafters

While there are seven standard types of roof rafters, three of them are most frequently in use:

• Common rafters: Sloped beams that run between the eaves and roof's ridge, providing support for the external roofing material.
• Hip rafter: As the name says, this roof rafter beam extends from the wall plate to the ridge at the angle of a hip roof.
• Valley rafter: Extending diagonally at a 45° angle between two intersecting wall plates to support the roof's ridge.

Roof Rafter Supporting Elements

• Barge board: A common element of homes with a gabled roof that runs parallel to the rafters to disguise those that run closest to its end.
• Fascia board: A piece of timber attached across the end of the rafters in order to disguise those not covered by barge board.
• Rafter boards shape the roof slope.
• Collar ties: Segments are installed between rafters to keep them secured and prevent them from spreading apart.
• Ceiling joists running horizontally to make the roof more rigid.
• Purlins provide additional strength to the extended ranges.

Roof Trusses 

A roof truss comprises two different elements. Chords make the exterior frames, while the inside contains a triangle structure called a web. Both elements are available in different shapes and sizes, to form a specific truss type. 

• King post: Commonly used in bridging short spans, such as garages, porches and outbuildings. 
• Queen post: Stands vertical upright with two webs on either side. 
• Fink truss: A more contemporary alternative to the queen post, with a ‘W’ shape between the chords.
• Double pitch profile: Often used in commercial buildings to create different roof pitches.
• Mono pitch truss: A 90-degrees angle single rafter used in lean-to roofs or single pitched roofs.
• Scissor truss: Also called “vaulted,” due to the ceiling types it’s used to create.
• Raised tie: Another type of truss designed for vaulted ceilings. 

Roof Sarking

Roof sarking consists of a pliable laminated membrane, positioned under the roof during installation to protect the frame from elements. Two basic types are permeable and non-permeable. 

Membrane Roofing 

Membrane roofing foils are available in three different styles, distinguished by their chemical properties.

• Cured elastomers: Also known as Thermoset, these membranes are composed of synthetic rubbers exposed to the "curing" or "vulcanisation process." Thermosets are appreciated for easy installation, high resistance to chemicals, impact, and high temperatures.
• Uncured elastomers: This type can be combined with Thermosets. It's generally installed similarly, either heat or solvent welded and then cured. However, uncured elastomers are rarely used today due to environmental concerns. 
• Plastomers: Often called Thermoplastics, these membranes are heat welded to form a much stronger bond than chemically bonded thermosets. 
• Modified bitumen – Polymer Modified Bitumen Membranes (PMBM) are composed of asphalt and reinforcing layers, premanufactured in sheets, with or without surfacing. 

Roof Underlays

Roof underlays are available in two different types.

• Non-breathable: Traditional bituminous products and waterproof polypropylene roof underlays make a cost-effective solution. They create an efficient secondary barrier against wind pressure and elements.
• Breathable: Modern, lightweight, low-resistance roofing papers, durable and easy to install. They are separated into two different types: vapour permeable (VP) and vapour-and-air permeable.

Roof Netting

Roof netting represents a safety measure, necessary for preventing a variety of hazards. A properly designed and installed roof safety net will prevent loose items, such as tiles or debris from falling. On flat roofs, it’s used for covering risky areas, making them safer for walking.

Roof Lining Types

Metal Roofing

The metal roofing system comprises metal boards, tiles, or panels, designed to provide air, water, heat, and sound resistance while enhancing structural support. It's appreciated for its appearance, impermeability, longevity, and overall high resistance as a building envelope component. Steel, zinc, and copper are materials commonly used in the production of metal roofing.

Clear Roofing

Clear roofing is an affordable and attractive roofing solution, typically available in polycarbonate versions. Its glass-resembling, lightweight, the transparent surface is available either completely clear or in a range of tinted versions. Clear roofing is a modern alternative to traditional roofing, durable and resistant to cracks or surface damages. 

Tiles & Slates

Roof slates and tiles look alike, and their role is similar. Still, some differences are useful to consider. 

• Roofing slate is a natural product, relatively rustic in appearance. Its colour palette is organic, often appearing in a range of greys, in different patterns and textures. Although coming with a higher initial price tag than many alternatives, this tile type pays off in its properties. It's exceptionally long-lasting - can hold well throughout centuries - as well as fire-resistant, with low maintenance requirements. 
• Roofing tiles are man-made, typically out of concrete or fired clay. Their design varieties are much broader than those of roof tiles, with a substantial palette of colours, textures, and patterns. Roof tiles tend to be more affordable than slates per square meter. They also need no sorting and grading, and the straightforward installation process makes them cost-effective in labour, too.

Roof Accessories

Roof accessories are vital components of a roof system, each playing a role in system protection. 

• Vapour control layers: Thin, airtight sheets placed between the substrate and thermal insulation to prevent movement and absorb excess humidity. 
• Protection, separation and levelling layers: Films set between incompatible layers to protect the waterproofing membrane.
• Drainage layers: Typically utilised in green roofs to block soil from falling through and provide drainage.
• Adhesives, cleaners and seam preparation agents: A variety of primers and enhancers used during roof installation. 
• Walkways: Used to provide non-slip pedestrian access to utility roofs and exposed roofing systems.
• Fastening products: Components made for mechanically fastened roofing systems for handling wind uplift forces and oxidation.
• Adhesive sealants: Used at edge flashings and penetrations to enhance the water-resistance properties of the system.
• Drainage products: Scuppers, drains, overflows and leaf guards.
• Prefabricated parts and flashing: A range of prefabricated pieces designed to ease membrane applications on different details.

Things to Consider Before Buying Roof Framing and Lining

A hard-wearing roof consists of many parts that work together to keep the building dry and comfortable. Therefore, the quality of each segment plays a role in the final result. 

Besides keeping the elements out, good roof framing will also allow fresh air to circulate. It's essential for preventing a buildup of heat and humidity in the attic. 

If you need assistance to find the right roof framing and lining for your home or office, ArchiPro provides a connection to the various professionals, ready to assist with all requirements and questions. Simply click "Contact supplier" on the product's page, or visit the supplier's website directly from the product's page.