What Is Pitched Roof | Types Of Pitched Roofs | Roof Covering For Pitched Roofs
What Is Pitched Roof?
The pitched roof is a sloping roof having the direction of slope downward. A pitched roof is also known as a sloping roof.
Types Of Pitched Roofs
Pitched roofs are divided into mainly three parts and they are as follows:
- Single Roofs
- Double Or Purlin Roofs
- Trussed Roofs
Single roofs are those roofs that have common rafters provided to each slope without any intermediate supports.
The single roofs are divided into 5 categories and they are as follows:
- Lean-To Roof
- Couple Roof
- Couple-Close Roof
- Collar Beam Roof
- Collar And Scissors Roof
The simplest form of the pitched roof is lean-to roof and the lean-to roof has only one slop surface.
In the construction of a Lean-to roof, the height of one wall is carried up higher than the other one to give a good slope to the roof.
A lean-to roof is mainly used for the construction of sheds, extensions, verandahs, etc.
Lean-to roof is suitable for the maximum span of 2.4 meters and rafters are secured on the wall plates.
The lean-to roof is also known as Pent Roof or Aisle Roof.
The main advantages of the lean-to roof are, it is affordable, prevents water and snow pooling, we can install lights and solar panels, etc.
Lean-to roof has some disadvantages, It is not good for big houses, not sustainable for high winds, Having drainage problems, etc.
We can use different types of materials while constructing the lean-to roof like we can use metal roofing, clay roofs tiles, Asphalt shingle roofing, Roll roofing, etc.
The couple roofing has two slope surfaces and these two surfaces are laying on the two same height walls.
In the couple roof, a common rafters slope provided upwards from the opposite walls and it meets on a ridge piece in the middle.
The couple roof is suitable for a span of up to 3.6 meters.
The advantages of the couple roof are these are light in weight, easy to construct, have a good slope so it is better for the drainage.
The main disadvantage of couple roofs is they are not much favored because it has the tendency to spread out at the feet.
The couple-close roof is similar to the couple roof the only difference is, in a couple-close roof there is a tie beam provided to the legs of the common rafters.
A couple-close roof is suitable up to a span of 4.2 meters without using a tie beam.
If we want to increase the size of the span or increase the load, then we have to use a tie beam to prevent the tendency of rafters to spread out.
The main advantages of the couple-close roof are, the tie beam can be used as a ceiling joist, and the triangular space created by the tie beam is used as storage space.
Collar Beam Roof
The collar beam roof is a modified version of the couple-close roof.
The main difference between the collar beam roof and the couple-close roof is, the tie beam in the collar beam roof is placed at a higher level than the couple-close roof.
The tie beam in the collar beam roof is known as the collar or collar beam and the lower is a collar, the stronger is the roof.
The collar beam roof is suitable for up to a maximum span of 4.8 meters.
The advantages of using of collar beam roof are, it increases the height of a room, a collar beam is used as a ceiling joist, and also provides a little space for storage.
Collar And Scissors Roof
Collar and Scissors roofs are similar to the collar beam roof except that there are two collar beams are provided in the collar and scissors.
These two collar beams are crossing each other to present the appearance of scissors.
Double Or Purlin Roofs
Double or purlin roofs are those roofs in which a purlin is introduced under the rafters.
The purlin is a horizontal structural member of a roof that is used as an intermediate supports in order to reduce the size of rafters.
The double or purlin roof is suitable for up to a span of 4.8 meters.
The main advantage of using a purlin roof is, it is suitable for the large roof because it handles the load.
Read More: What Is Roof? | Types Of Roofs | Terminology Of Roofs | Requirements of Good Roof
Trussed roofs are those roofs that have a span size greater than 4.8 meters and there is no inside supporting walls or partition for purlins.
In the trussed roofs the common rafters rest on the ridge piece and purlins.
In the trussed roofs the rafters support the roofing materials, purlins provide intermediate supports to rafters and trusses support the ends of purlins.
Trussed roofs are subdivided into seven parts and they are as follow:
- King-Post Truss Roof
- Queen-Post Truss Roof
- Mansard Truss Roof
- Truncated Truss Roof
- Bel-Fast Truss Roof
- Steel Truss Roof
- Composite Truss Roof
King-Post Truss Roof
The king post is a central vertical post that forms a support for the tie beam.
In the king post truss roof, the inclined members are known as the struts that prevent the principal rafters from bending in the middle.
The king-post truss is suitable for roofs having spans varying from 5 meters to 8 meters.
Queen-Post Truss Roof
The queen-post truss roofs are those roofs that have two vertical members (called queen-post).
A queen-post truss roof is suitable for the roof having a span varying from 8 meters to 12 meters.
The main difference between the queen-post truss roof and the king-post truss roof is, queen-post has two vertical members whereas the king post has only one.
The mansard truss consists of the king-post and queen-post trusses and it has two pitches, the upper pitch, and the lower pitch.
Mansard truss is a two-storey truss, the upper portion consisting of king post truss and the lower one consisting queen post truss.
The disadvantage of the mansard truss is, it is old and ugly in appearance.
The truncated truss is similar to the mansard truss. The only difference is the truncated truss top is finished flat with a slope to one side.
The truncated truss is used when a room is needed in the roof.
Bel-Fast truss is suitable for a span length up to 30 meters. And it is also known as latticed roof truss or low string truss.
The bel-fast truss is in the form of a bow and it consists of a thin section of timber.
The steel trusses are used for spans greater than 12 meters.
In India, steel trusses are selected over timber trusses due to the big differences in the costs.
The composite trusses consist of steel members and wooden members.
The advantage of composite trusses is, they are economical and light in weight.
Roof Covering For Pitched Roofs
Here are the lists of roof covering which are mainly used for pitched roof covering:
- Asbestos Cement Corrugated Sheets
- Eternit Slates
- Patent Tiles
Asbestos Cement Corrugated Sheets
These types of sheets have a series of waves on the sheets and they are used for the factories, workshops, garages, big halls, etc.
These sheets do not require any type of protective paint and can not be eaten by vermins.
These sheets are cheap, fire-resisting, lightweight, strong, and durable.
Eternit slates are fire-resisting, lightweight, and colorful, and weather resistant.
Around 8 sheets are required for the covering of one square meter of roof area.
Manglore tiles are patent tiles that are widely used as a roof covering for pitched roofs.
Around fifteen manglore tiles are required to cover one square meter of roof area.
These are the wood roof covering and the wood shingles are mainly used for the covering of roofs.
The shingles are mainly used in hilly areas where the wood is easily available.
Frequently Asked Questions (FAQ)
The main difference between the couple roof and couple-close roof is, in the couple roof there is not any tie beam is provided but in the couple-close roof, there is a tie beam.
The single roofs are five types and they are as follows:
1 Lean-To Roof
2 Couple Roof
3 Couple-Close Roof
4 Collar Beam Roof
5 Collar And Scissors Roof
The double or purline is also known as the rafter and purlin roof.
Following factors should consider while selecting a roof covering for a pitched roof:
1 Climate of the locality
2 Nature of the building
3 Availability of material
5 Maintenance costs etc.