Purlins are used on double roofs. They effectively reduce the span of the rafters and limit their size to ecenomical sections.
I believe you are referring to an area of the roof called a valley. A valley is formed anywhere the downward slope of two roof surfaces meet.
atrium
If the gable is formed by the two slopes and a horizontal line, it is called a gable roof.
The slabs that are supported only at end are called simply supported slabs i.e. there is no intermediate supports in the slab and there will be no support moment acting on the slab.
Continuous roof systems are called membrane roofing. This roofs are used for buildings and tanks. They are built on flat or nearly flat roofs to prevent leaks and help drain water off.
Purlins are commonly used to support roofs. Purlins are horizontal in shape; it commonly supports rafters that hold up the roof. Thus purlins are quite heavy.
portico
It's called a pallate.
A longitudinal member in a roof frame, usually for supporting common rafters or the like between the plate and the ridge. One of several horizontal timbers supporting the rafters of a roof. http://www.bw-industries.co.uk/roof-purlins.htm
Purlins are horizontal members fixed on top of a rafter. The purlins support the roofing sheets.
Purlins are horizontal beams or bars that support a building's structure; they are typically located beneath the roof. The walls or rafters of the building are used to secure the purlins in position. They can replace tightly spaced rafters in wood-frame buildings, although their main use is in metal buildings. Without the purlins, there would be no framework on which the roof covering could rest. Purlins are therefore an essential component of building a roof. When used with fiber cement sheets, wood purlin is an excellent material. Pre-punched purlins that adhere to a standard design may be provided by us, or they can be tailored to precisely satisfy your needs. Despite the fact that we only carry a limited quantity of galvanized purlins in store, we fabricate every steel roof purlin to order. Maxroof is engaged in offering supreme quality Purlins & Girts, which are installed widely in both commercial and industrial establishments. For more information, please go to our news section. In accordance with the specific requirements of every customer, our company is able to produce an extensive selection of fully customizable roof flashing components. For more details visit our website today: Call us: (+91) 841 196 0014 Office Address: B-414, 4th Floor, Pride Purple Square, Kalewadi Phata, Kaspate Wasti, Wakad, Pune - 411 057. Maharashtra , INDIA.
If installed correctly then yes you can on most systems. This depends on the spacing of your purlins, the type of metal used, the panel style used, the thickness of metal used, and the slope of the roof.
False
opposite
except the red purlins, all purlins are first to be placed in the container
A truss is the structure that holds the roof(or bridge or whatever). Purlins are members holding a few trusses together. A truss is a simple frame made from two force members.
it is called a roof