Hi i am thinking of having my loft converted i need to move the purlins down to do this i need to install new 6x2 rafters next to the 4x2 rafters.
Moving roof purlins.
The exisiting purlin is 10 2 i will replace like for like.
The purlins you refer to i think would more properly be called either collar ties or rafter ties.
A purlin plate in wood construction is also called an arcade plate in european english under purlin and principal purlin.
Purlin plates in wooden construction.
I will be putting in 9x3 floor joists.
By supporting the rafters they allow longer spans than the rafters alone.
What s the point of moving the purlin anyway just clean it up and expose it or board it.
Snap the third chalk line two more feet down and continue down the roof until it is covered with purlins.
Install the second row of purlins just like the first cutting the end piece to fit.
This one has held the roof straight for 60 years so no need to change i think.
Mike mikewilliams416 13 aug 2012 1.
Move two feet down the roof and snap a horizontal chalk line.
Purlin plates are beams which support the mid span of rafters and are supported by posts.
My question is how do i prop up the rafters so i can take down the existing purlin to insert the new rafters before building a timber structural wall further down to support the rafters the roof.
How to install purlins.
The term plate means a major horizontal supporting timber.
The rule of thumb is to locate these cross braces one third of the distance below the ridge.
In order for the sheets to be easily fixed to the purlins as a rough guide they should be at least 50mm wide.
These help prevent separation at the ridge as a tension brace and also help prevent rafter sag from roof loading as a compression brace.
Snap the third chalk line two more feet down and continue down the roof until it is covered with purlins.
Internal roof elements to consider during loft conversions consist of a number of sub structures such as ridge boards rafters purlins joists wall plates and steel beams.
In the roof space as the name suggests the ridge board is the length of timber which runs horizontally along the apex of the roof.
Any expert views much appreciated.
