When you are constructing a new roof, you need to take into consideration a few key factors which the roof will have to comply with. These include things such as providing resistance to heat loss, resisting inclement weather and being able to support loads put onto the roof.
Extra loading on the roof needn't be this extreme to need to be taken into consideration
Roof loading
It might not be at the forefront of your mind during the roof construction, but your roof has to cope with a good degree loads put onto it by various means. These include:
- Roofing materials such as timbers, slates or tiles and insulation
- Weather that may affect the roof such as heavy rain, wind or snow
- Person access - your roof will need to support the weight of a person who climbs into it to do maintenance
Roofing Materials
Profile concrete tiles can reduce the weight of the roof considerably if you don't want to reinforce the rafters and batten. For areas where slate roofs predominate, fibre cement slates or reconstituted slates can also reduce the weight on your roof from the actual roofing materials.
Weather
In areas which experience heavy snowfall, the potential, sizable weight on the roof must be taken into consideration as, across a surface as large as a roof, this can add a considerable percentage to the load on the roof. On low pitch roofs this is a particular problem as the amount of snow that can accumulate is much greater.
High pitch, more vertical roofs have much less problems with accumulation of snow or water but the large exposed area will take a considerable load from the wind that should be calculated by an architect or engineer.
Person Access
As well as the weight of people on the roof to perform repairs or maintenance, if the roof is also used as an emergency escape route, then the additional weight should be considered. While a top hung roof window used as a means of escape won't add anything to the roof loading, if a number of people will be exiting that way, will.
Roof spreading
Many people now want a loft conversion to make the most of the available space they have in their home. The problem with this is that ceiling joists may be removed or connective timbers removed to create the desired space. A pitched roof will always want to spread apart and any joists that are removed may compromise the integrity of the roof structure, especially where roof loading is concerned. Before you undertake any work changing the internal design of the roof structure, you should consult a structural engineer.
