When designing your extension we have available many different styles of roof and materials of construction. What you select and how it will work are very important for you.
The Planning Permission process will have a primary input in what style can be built and what it is made from. If you are going through the Permitted Development process the authority will want roof style and materials to be similar to the existing structure. Same too for conservation areas, and listed properties will require careful consideration of what is already fitted.
Building regulations will dictate construction with two main types of design available – a “Warm” roof and a “Cold” roof. Both will conform to regulations and give a great space to live in.
What is a warm roof, I hear you ask?
A Warm Roof moves the insulation layer above the roof supporting joist structure. This gives a thicker roof profile, but removes the potential cold spots that can form with the joists connecting with the internal facing.
So what about a cold roof?
A Cold Roof structure has the insulation layer positioned typically between the roof supporting joists. It can allow cold spots when the heat transfers straight through the joists, but will give a slimmer roof thickness.
Apex style pitched roof
This provides a sloping surface which can take a variety of coverings such as glass, slates, tiles, and shingles. Internally, this can give a vaulted style of room which can be a real character of the building.
Also more exotic solid panels cladding can be fitted with metal roof coverings such as Copper, Zinc and Lead.
Lean To roof
This is in effect a half apex with a monopitch. Generally with an extension the slope can be limited by the first floor windows. Hence this will require careful material selection; something Appropriate Design Solutions can help you choose.
This provides a slope to the gable (the side perpendicular to the main roof slope) and can give a more gentle appearance. This can be modified further with a Barn Hip which slopes only for a portion of the gable slope.
This can be useful where headroom is limited. It can give a good room height internally, while limiting the headroom required externally. Traditionally, old style flat roofs were short lived as the felt material was not really suitable for the UK climate. Certainly not the case now, as there are many really good and durable coverings available which will be able to give a really long lifespan.
Often a glazed lantern or roof light will be incorporated within a flat roof greatly increasing the useability of internal rooms beneath with the inclusion of light.
It is possible to introduce flat roof lights within the roof. If this is on a flat roof the roof light may get dirty very quickly and require more maintenance.
This provides a modified flat roof with a sloping perimeter. This works well with period properties and gives a much more gentle appearance externally. This can also be sunken to further increase the internal headroom available.
For sloping roofs the choice of covering must take into account the steepness of the slope angle. Some materials such as tiles and slates have a limit of 30 degrees or so. It pays to check what slope your desired material will work to.
It is possible to utilise a weather-proof membrane underneath the roof covering to reduce the slope of a tiled or slate roof down to 10 degrees or so. This solution generally adds significant cost and never appears to look right from a design perspective.
For a self cleaning type of glass roof this can be fitted to a very shallow angle of approx 10 degrees. This can make a big impact on headroom available, particularly as the roof thickness can be small.
Solid Panel type roofs can be utilised with some unusual materials. Metal panels, with Lead, Copper and Zinc often used. There are also profiled steel colour coated systems available which are crossovers from industrial building construction.
While it is still available it does not make any sense to use traditional Felt roof covering on anything other than maybe a shed or garden building. It simply is not durable enough for modern day building, and carries a bad reputation for causing leaks and excessive maintenance costs. There are many better materials available that Appropriate Design Solutions can help you choose from.
Using a modern synthetic reinforced “rubber” material, seam welded for a jointless surface and bonded to a multi layer board structure the roof surface will be serviceable for many years (25+ years not uncommon) and also give an aesthetically pleasing surface. This without the costs of traditional materials such as lead.
Of course, traditional materials can be used. Lead is a typical material but it is not entirely maintenance free, and can leak through cracks forming in the joints. However the construction typically will include mopstick type joints which are great for heritage appearance but also introduce more joints and joints = leaks..