A pitched roof is made up of four main elements.
Principles of pitched roof construction.
There are a number of ways to design and construct pitched roofs using timber.
The minimum pitch however that can be used with many roofing materials such as asphalt shingles or corrugated metal is 3 in 12 3 12 pitch.
The pitch of a roof is its vertical rise divided by its horizontal span and is a measure of its steepness.
This can be determined by the size of the timbers or the size of the roof.
Slopes greater than 18 12 are found on a frame roofs and some mansard style.
A breathable membrane or in older properties roofing felt also sometimes called sarking felt or slaters felt which keeps the rain out whilst the roof is being built and offers secondary protection to any water that gets.
Wooden joists to support the weight of the roof.
There are a couple of different methods for constructing pitched style roofs.
Depending on the building design it can bring along many environmental benefits.
Principles of pitched roof construction.
If making a warm pitched roof construction you should opt for some type of rigid insulation boards such as kingspan k7 pitched roof board or celotex xr4000 pir insulation boards which can be installed both between and over the rafters and offers a level of fire resistance if important and applicable.
There are two basic methods of pitched roof construction.
A truss roof using factory made trusses which are delivered to site complete and just erected.
It is simple in design economical to.
In this method there are joists and rafters.
However in practise they tend to be much shallower commonly being expressed as a gradient and can be anywhere from 1 40 to 1 80.
Gable a gable roof has a ridge at the center and slopes in two directions.
One pitched roof construction method is a cut roof method.
It is the form most commonly used by the navy.
An example of each is shown in figure 2 1.
A cut roof this is the traditional method of cutting the timber on site and building up the roof using rafters ridge boards joists and purlins etc the exact details being determined by the size of roof size of timbers etc.
Following the second world war various forms of prefabricated truss were developed with the intermediate rafters and purlins cut and fitted on site.
Environmental value pitched roof construction when carried out with clay tiles performs much better than flat roofs.
For lower pitches a built up or continuous roll roofing must be applied to keep the roof waterproof.
If asphalt shingles are to be installed on a low slope roof special steps are required to avoid short roof life and roof leaks.
Low slope roofs are from 0 to 3 12 in pitch.
Some sources consider low slope to include 3 12 pitch roofs.
Economic value pitched roofs provide high value as they offer more living space as compared to flat roofed buildings.
Traditionally builders constructed them on site cutting and fitting each piece to its neighbours.
This is more of a traditional manner in regards to cutting the timber while onsite and building up the roof by the use of rafters ridge boards joists and purlins among others.
A pitched roof is in contrast to a flat roof which technically is any roof with a slope less than 10.
They have a long life span and are easy on maintenance.
