porch valley

[dancn]

One of the last bits of my new roof is over the porch.
Porch wallplates are on,
It’s intersecting the main roof at 90degrees.

I really don’t need internal access so hope to use a valley lay board instead of a valley rafter.

I have no probs with the ridge and commons, but is it tricky getting the bevels for the jacks, and accurately positioning the layboard.
Roof pitch is 40 degrees

Anyone have a sketch for setting out, and tips for getting the jack bevels



Thanks

 

[noseall]

You use the existing rafters to position the layboard by using a straight edge across full rafters, extending the straight edge until it touches the roof both at ridge point and eaves.

We normally drop the layboard roughly into position then use the straight edge for fine adjustments and final positioning. At no time should the lay board raise the straight edge above any of the existing rafters.

I trial and error the top and bottom layboard cuts (on the layboard itself), but use a tape measure to get the rafter lay-seat cut, i.e. the position where the rafter sits on the layboard.

The seat cut is usually an obtuse angle that is splayed to the pitch of the roof.

Try out some trial cuts using a level stretched between the ridge board and the lay board, but use shortish bits checking the top and bottom cuts individually. The level will keep the short trial piece on line.

 

[dancn]

thanks noseall

I've a 6X2 rafters and thinking of a 9X2 for the layboard.

I'm Visualizing the layboard itself requiring a beveled edge along the valley centerline, to avoid a step,Or is this not really required. I’m planning to use a 9X1 valley board

It will probably be easier when I try it in reality , or harder

 

[noseall]

There is no need for bevelling as you align the uppermost edge of the layboard with the rafter top. In fact, you need the definition of the angle to highlight where the stopping point is for the seat cut and a point to which you can measure.

Believe it or not but even a 9"x 2" may not be enough width on the layboard to collect the whole cut. It will be fine for say a ridge with a 40 degree cut, but because the layboard cut is so obtuse then you may need to lay another timber along side, say a 3"x 2" or similar.