Domestic Roof Construction: A Comprehensive Guide

Building a domestic roof requires careful planning and execution to ensure it's safe, durable, and aesthetically pleasing.

A typical domestic roof is designed to withstand various weather conditions, including heavy rainfall and strong winds, with a lifespan of around 20-30 years.

The choice of roofing material depends on the climate, budget, and personal preference, with options ranging from asphalt shingles to metal roofing.

For a standard pitched roof, the pitch is usually between 20-40 degrees, with a higher pitch providing better water runoff.

A typical domestic roof consists of several layers, including the underlayment, roofing felt, and shingles or tiles.

Proper ventilation is essential to prevent moisture buildup and ensure a healthy roof environment.

To start building a roof, you'll need a few essential tools and materials. A tape measure is a must-have for taking precise measurements of your roof's dimensions.

You'll also need a chalk line to mark straight lines on your roof's surface. This will help you ensure that your roof's layout is accurate and even.

A claw hammer is another crucial tool for driving nails and fitting pieces of wood together. Make sure it's sturdy and well-balanced for comfortable use.

A cordless drill is also a vital tool for drilling holes and driving screws. This will save you a lot of time and effort compared to using a manual drill.

For cutting through metal or plastic roofing materials, you'll need scissors or cutting pliers. These will help you make precise cuts without damaging the surrounding material.

Here's a list of the tools you'll need to get started:

A roof has to have the ability to carry the self-weight of the roof covering and structure and be able to resist forces from winds and the applied load of snow.

The structure should be built as light as current technologies allow to keep imposed loads on the supporting walls to a minimum.

A well-designed roof structure can make a big difference in the overall stability and safety of a building.

Purlin roofs were introduced to increase potential roof spans without compromising wall stability, allowing a potential span of 8 m.

By installing a purlin into the roof structure, rafters were given extra support and no longer needed to be as thick and heavy.

Purlins were often built into gable walls for extra support, but in solid walls, this exposed the end of the purlin to potential rot attack from the dampness in the brickwork.

Internal load-bearing walls allowed smaller ceiling joists to be used and were positioned to cover the shortest distance across a room as possible.

Hangers and binders were used to stop the ceiling joists from sagging, and struts were used to support purlins and reduce the size of the purlins needed.

Purlin roofs were constructed on site, requiring many sections of timber to be assembled to form the final structure, which was very labour intensive and required skilled craftsmen.

The benefit of this form of roof was that by using struts, much of the roof space could be utilised for storage and ultimately allowed the space to be used for accommodation if needed via a loft conversion.

A roof has to be strong enough to carry its own weight and withstand external forces like wind and snow. This is crucial to ensure the roof's stability and safety.

The structure should be built as light as possible to minimize imposed loads on the supporting walls. This not only reduces the risk of damage but also helps to find the most economic means of carrying the roof structure and its load.

To achieve this, the roof design and structure must be carefully planned and executed to resist forces from winds and the applied load of snow.

As you start building your roof, it's essential to consider ventilation. The rafter roll should come out above any pre-installed insulation to prevent condensation.

To install the rafter roll, tack it to the rafters, starting on the left-hand side and working your way across. Avoid draping it too much, but don't pull it too tight either, or you'll lose the corrugated shape that channels the air flow.

The ventilation system features an integrated grille that allows air to permeate while keeping debris out, and it also prevents the underlay from sagging into the roof cavity, which can cause damp.

To build a roof, start by ensuring the rafter roll comes out above any pre-installed insulation to prevent condensation.

The rafter roll should be tacked to the rafters, beginning on the left-hand side and working across, with a balance between draping and tightness to maintain airflow.

An integrated grille in the low-level ventilation system allows air to permeate while keeping debris out, and prevents the underlay from sagging into the roof cavity.

Make sure to use the right size timber battens for your roof tiles, checking with your supplier if unsure.

Line up the top of the batten with your chalk line and fix with a nail to every rafter across the length of the roof.

Leave off the final batten for now, as it will need to be installed after the ridge batten and straps.

Fold batten straps into shape away from the roof for the best fit.

Check with your supplier for the height needed for your ridge batten and fix it in place with your batten strap.

Repeat along the length of the roof, fixing to the rafters as you go.

Install your eaves to ridge closure system over the edge of the tile, screwing it into the bargeboard or fixing with a clip to the top of the fascia.

Finish off by installing the verge units as per the manufacturer's instructions.

To determine the first fix point on the roof for your tiles, find the hanging length of your tile and subtract the length that will overhang the roof.

The result of this calculation is where the top of your first batten will sit. This is crucial to ensure the roof tile doesn't fail.

You need to determine your top fix point, which may be taken from your ridge system of choice. Check manufacturer's guidance for this information.

The distance between the top and first fix points will tell you where you need to fit your battens. Make a note of the minimum and maximum gauge/batten spacing for the tile to prevent failure.

To calculate the number of courses of tiles you'll need, divide the distance between first and top battens by the maximum gauge for the tile. Round up to the nearest whole number to ensure you have enough tiles.

This calculation will give you a good idea of how many courses of tiles you'll need. However, double-check the gauge sits between the minimum and maximum requirements by dividing the length between the top and first fix points by the number of courses.

Mark out the fix points on the left and right sides of the roof using a chalk line to ensure a straight line across the roof. This will be the guide for where the top of each batten should sit.

Be sure to consider the verge system when measuring for your battens, as you may need to leave an overhang on one side to install it.

A ridged roof consists of declined rafters that rest on vertical wall-plates on top of each wall, with the top ends meeting at the horizontal ridge plate or ridge beam.

The ridge plate or ridge beam is the horizontal beam that runs along the top of the roof, where the rafters meet. It's a crucial component that helps distribute the weight of the roof evenly.

To ensure the ridge is secure, you'll need to lay a breathable ridge membrane in a straight line across the ridge batten, fixing it under the verge system and one end of the roof. This provides a solid foundation for the ridge tiles.

Ridge tiles are then screwed to the ridge batten, with a ridge-to-ridge seal installed between them to offer extra strength and a mechanical fix. This seal helps prevent water from seeping into the roof and causing damage.

Regular inspections are a must to catch minor issues before they become major problems. Conducting inspections at least twice a year can help identify problems early on.

Clogged gutters are a common issue that can cause water to back up and damage the roof. Regular gutter cleaning ensures proper water drainage.

Trimming overhanging branches is essential to prevent damage to roofing materials and pest infestations. Keeping branches trimmed back can save you from costly repairs down the line.

Ignoring minor repairs can lead to more significant problems, so it's essential to address issues like missing shingles or small leaks promptly. This can save you money in the long run and prevent further damage.

Proper attic insulation helps maintain a consistent temperature, reducing the risk of ice dams in winter and overheating in summer. This can lead to energy savings and a more comfortable living space.

Asphalt shingles are the most popular roofing material due to their affordability and durability. They come in various colors and styles, making them a versatile choice for many homeowners.

Metal roofing is known for its longevity and resistance to extreme weather conditions.

Slate roofing can last for over a century with proper maintenance, although it's more expensive.

Tile roofing provides excellent insulation and is highly resistant to fire and weather damage, making it a popular choice in areas with warm climates.

Wood shingles and shakes offer a natural and rustic look, but they require more maintenance and provide excellent insulation.

A simple ridged roof consists of declined rafters that rest on vertical wall-plates on top of each wall. The top ends of the rafters meet at the horizontal ridge plate or ridge beam.

The rafters, tie beams, and joists serve to transmit the weight of the roof to the walls of the building. They can be supported by various structural systems, such as wall-plates, hammer-beams, and king posts.

In cyclone and hurricane prone areas, the main engineering consideration is to hold the roof down during severe storms. This is achieved by making every component of the roof, including the rest of the structure, withstand the uplift forces of high wind speeds.

Pitched roofs are a common sight in many homes and buildings. They're often used because they're efficient and can be designed to accommodate different pitch angles.

The most common form of trussed rafter is the fink or 'w' truss, which can span up to 12 m. This type of truss is capable of withstanding many different pitch angles.

Trussed rafters have a significant advantage over traditional methods of fixing, as they use punched metal connector plates, also known as 'gang nails', which were introduced in the 1960s. These plates increase the strength of the rafter and reduce timber usage.

Factory assembly of trussed rafters saves valuable time and speeds up the construction process, which is essential in today's industry. This is a crucial factor in modern construction.

A timber wall plate is still used as a fixing point for the rafters, placed on top of the internal leaf of the cavity wall on a mortar bed.

A closed couple roof is a type of roof construction where the ceiling joists are added to the couple roof form to increase its security and potential roof-span.

By adding ceiling joists, typically 75 x 50 mm, the structure becomes much more secure, with the joist acting as a tie to prevent the outward deflection of the wall.

The joists are secured to the rafter feet rather than the wall plate to prevent any potential deflection, making a secure connection between the rafter and ceiling joist critical.

Ridgeboards provide restraint for the top of the rafters, preventing lateral movement, and the timber used for ceiling joists is often thinner than the rafters, requiring support.

Internal load-bearing walls often provided this support, but in their absence, 'hangers' and 'binders' were used to secure the ceiling joists.

Binders were nailed to the centres of each ceiling joist parallel to the ridgeboard and were often built into the gable wall for extra support.

The use of hangers and binders reduced the need for large ceiling joists, but also introduced problems like damp penetration, timber rot, and the risk of compromising the supporting wall.

Hangers, lengths of wood attached to the ridgeboard, supported the binders and helped distribute the weight of the roof more evenly.

Collar roofs allowed for some economies by reducing the height of external walls and the amount of brickwork needed.

Raising the ceiling joists to construct upper rooms in the roof space can be a good idea, but it has its limitations.

The maximum height a ceiling joist can be lifted to is 1/3 of the height of the roof to maintain stability.

This reduced span to approximately 4 meters, which might not be suitable for all roof constructions.

Lifting the ceiling joist reduces its restraining force, increasing the instability of the supporting walls.

By understanding these limitations, builders can make informed decisions about using collar roofs in their projects.

A ridged roof is a classic construction type that's been used for centuries. It's a simple yet effective design that's still widely used today.

The rafters, which are the sloping beams that make up the roof, rest on vertical wall-plates on top of each wall. This provides a solid foundation for the roof.

The top ends of the rafters meet at the horizontal ridge plate or ridge beam, which is a crucial structural element that helps to distribute the weight of the roof.

Heavier under purlins are used to support longer rafter spans, ensuring that the roof remains stable and secure.

Tie beams or ceiling joists are connected between the lower ends of opposite rafters to prevent them from spreading and forcing the walls apart.

In areas prone to high winds, such as cyclone and hurricane zones, the main engineering consideration is to hold the roof down during severe storms. This requires every component of the roof to withstand the uplift forces of high wind speeds.

Modern roofing technologies have made it possible to create secure and durable ridged roofs, even in areas with harsh weather conditions.