Roofing Essentials FAQ's

Choosing a new roof requires more thought than simply choosing a tile and colour. There are a range of considerations including:

Pitch:

The pitch of your roof will dictate what products you can use. It is important to remember that different products can only be laid at certain pitches. Details of the pitch performance of our products can be found by using our roofing selector, or in the current literature.

Materials:

Clay – Is a traditional product bringing warmth and character to a building and is available in a wide range of colours and styles from the modern and precise through to heritage handcrafted. Clay roof tiles offer exceptional long term aesthetics and performance.

Concrete – For many years concrete has been the most common roofing material in Britain. Concrete provides an affordable alternative to natural materials and is available in a wide range of profiles, shapes and colours to suit a multitude of roof types.

Colour/Texture/Profile:

Marley's range of concrete and clay tiles and fibre cement slates come in a variety of colours, textures and profiles all able to achieve a unique aesthetic.

Weight:

It is important to ensure that the roof structure can support your chosen roof covering with consideration given to other loadings such as snow and wind. If the existing structure has weight restrictions, then an alternative might be to use fibre cement slates that offer a low weight, securely fixed solution.

Roof Design:

Complex roof designs may also be a factor in what product you are able to choose as your roof covering. A roof incorporating a lot of features and potential tile cuts may be more suitable to small clay or concrete plain tiles.

Sustainability:

The roof is without doubt a key meteorological interface between the building and the environment and creates an ideal platform for sustainable technologies such as photovoltaic, or solar thermal panels, or more recently, pollution busting tiles like EcoLogic.

Rafter Lengths:

The length of the rafter has a direct effect on the speed at which water drains from the roof. The longer the rafter, the longer the water takes to drain. In instances of long rafter lengths, it may better to use profiled tiles that provide channels and increased speed of drainage. If unsure, please contact the Marley technical department on 01283 722588.

Planning:

The UK is an amalgamation of many regional styles in terms of roofing products. For example, areas such as the North West are commonly associated with slate type products, whilst other areas such as the South East will have an abundance of clay roofs. It is important that whatever product you wish to choose is in keeping with the local vernacular and meets with local planning requirements if applicable to the property.

Other considerations relate to, fixing, ventilation, dry fix and the use of mortar.

This might seem a lot to think about, but Marley have a wealth of expertise available to help you every step of the way. Call our technical team on 01283 722588, or access our suite of technical tools which can provide you with estimates, National Building Specifications, or fixing specifications.

The cost of a new roof depends of a variety of factors, such as:

• Size and complexity of the roof
• Choice of product
• Location
• Fittings and accessories (dry fix and ventilation)

For example: Re-roofing a typical semi-detached property in standard concrete interlocking tiles can cost anything between £3500 - £5500.

It is important that you get a range of quotes from a few roofing contractors and ensure you know what materials are being quoted for. Don’t be frightened of asking for a particular product if there is one you like the look of. You may be surprised to find it’s more affordable than you think.

There are many different kinds of underlay available on the market which can be split into two different categories:

Non Breathable (1F Bitumen or plastic)

These include bituminous and impermeable plastic products. These are seen as affordable and functional, designed to provide an effective secondary barrier against water penetration.

Breathable (vapour permeable or air open)

These are generally more expensive than standard underlays and as well as providing a barrier to water penetration, may also offer some benefit in terms of roof ventilation. It is important to note that there is a difference between the two recognised types of breathable underlay which will greatly influence the ventilation performance of your roof. Further details can be found in the ventilation FAQ’s.

All tiles and slates have a minimum roof pitch which is set out in order to protect the roof from water penetration. The minimum pitch for each product can be found either in the product brochure or within the products pages on the website located within the technical tab. Some tiles and slates incorporate design features allowing them to be laid at a low minimum pitch. Low pitches are often found on extensions to properties where the angle of the roof is limited due to obstructions such as second floor windows.

For more information visit our 'What is the minimum pitch for a roof tile or slate?' blog post

Marley has several options for roofs with a low pitch:

Wessex – A large format interlocking tile with a subtle square profile – Capable of being laid down to 15°

Mendip 12.5 – A large format interlocking pan-tile – Capable of being laid down to 12.5°

It is important to remember that local building surveyors will almost always check the roof tile or slate is suitable for your pitch. Laying a product below its minimum pitch can prove to be a costly mistake, so it is always important to check what it being used and whether it is suitable.

It is uncommon to find a pitched roof below 15° and there are several products within the Marley range that can be laid at this pitch. In the rare instance that your roof is below 15° you do have options available to you.

• There are several manufactures that provide flexible bituminous sheeting systems laid underneath the tiles, but these will always raise the overall height of the roof, which can be problematic if you have obstructions such as windows.

• You could consider using a marine plywood deck which can be installed using counter battens to provide adequate means of ventilation. It is always recommended that you contact the technical advisory service if you are unsure.

Each year as many as 200,000 buildings in the UK are damaged by gales. Roof damage represents by far the largest sector of the total number of building elements affected. Roof tiles and slates tend to vary according to how they are fixed. For example, all concrete plain and clay plain tiles (due to their small size) have to be fixed. Large format concrete tiles are generally more secure by their natural weight, but do require a minimum level of fixing. The weight and size of a concrete tile means that it is not always necessary to fix every one, however dependent on product, exposure and location, may require some or all of the tiles to be nailed and clipped.

Marley is able to produce bespoke fixing specifications for any roof design based on a number of factors:

Environment – Average wind speeds and loadings
Location – How exposed is the roof? Local topography
Roof design – Is the roof a steep or shallow pitch?
Building height – Is the roof level high?
Product choice – Weight of product, leading edge?
Fixing specifications will always follow BS5534 which provides a calculation for assessing the wind load on each tile or slate as a uniformly distributed load and also takes into account the porosity of the tiles or slates and the effectiveness of the substrate.

Eaves: Means 'edge' and the eaves of a roof is its lowest edge. The eaves may terminate flush with the outer face of the wall when it is known as a 'flush eves' or it may project.

Verge: The edge of a roof which runs from eaves to ridge at a gable.

Ridge: The highest point of a pitched roof that receives the head of the spars (common rafters/rafters). Ridge Tile: A purpose designed tile that covers the ridge of a pitched roof.

Hipped Roof: A term used to describe a pitched roof, the ends of which are also sloped

Valley: Formed by the intersection of two roof surfaces having an external angle less than 180º. The wood member at the intersection is called the valley rafter and the feet of short spars are nailed to the valley rafter.

Abutment: Where two structures meet. Commonly seen in extensions, where the new pitched roof joins on a wall.

Find out more about the different parts of a roof in our 'What are the different parts of a roof?' blog post.