Moving Roof Purlins

This one has held the roof straight for 60 years so no need to change i think.

Moving roof purlins.

A purlin plate in wood construction is also called an arcade plate in european english under purlin and principal purlin. I will be putting in 9x3 floor joists. When positioned roof purlins should be spaced no further than 1 2 metres apart when using sheeting with a thickness of 0 7mm and 1 metre when using 0 5mm sheeting. 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.

In order for the sheets to be easily fixed to the purlins as a rough guide they should be at least 50mm wide. By supporting the rafters they allow longer spans than the rafters alone. Move two feet down the roof and snap a horizontal chalk line. These help prevent separation at the ridge as a tension brace and also help prevent rafter sag from roof loading as a compression brace.

Move two feet down the roof and snap a horizontal chalk line. Install the second row of purlins just like the first cutting the end piece to fit. Snap the third chalk line two more feet down and continue down the roof until it is covered with purlins. The term plate means a major horizontal supporting timber.

Snap the third chalk line two more feet down and continue down the roof until it is covered with purlins. Mike mikewilliams416 13 aug 2012 1. Purlin plates are beams which support the mid span of rafters and are supported by posts. The purlins you refer to i think would more properly be called either collar ties or rafter ties.

The exisiting purlin is 10 2 i will replace like for like. The rule of thumb is to locate these cross braces one third of the distance below the ridge. What s the point of moving the purlin anyway just clean it up and expose it or board it. How to install 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. Any expert views much appreciated. 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.