With the third option crossbars with side rails you can secure an item to the side rails and run tie downs from front to back securing them to the crossbars.
How to attach wood to a roof rack.
What types of tie downs work best.
Makes it a lot harder for the winds to lift it up.
I transport 4x8 plywood on my roof racks i usually run a couple of 2x4s under the roof racks the full length of the ply and strap to those at the front and back as well as strapping to the actual roof racks.
To attach the metal braces to these blocks i cut a section out of each side of the blocking a curved fashion using the same method of incremental 1 8 cuts using the table saw fence.
Second trip 16 2 x4 x6 boards on my roof rack.
Secure it to the roof rack.
On each side of the roof you ll see a rack that runs the length of the roof of the vehicle.
A pair of 20 web ratchets used as a fail safe in case the board slides to the rear of the vehicle.
Use a tie down that wraps around the item and the rails.
Rusticdavid woodworklessons woodworkingforbeginners david shows how to tie wood boards and sheets of plywood safely and securely to your cars roof rack dav.
To attach the four saddles to the rails i again used blocks of oak similar in size to the roof rack blocks.
My car with 4 x8 mdf board on the roof rack.
In case you have no idea how much weight your plywood sheet is a sheet of inch plywood is approximately 100.
Oh and remember to.
Remember to place a distance of about 3 to 3 foot in between.
My car with roof rack with cross bars installed.
4 web ratchet straps in a pair of x formations to hold down the board to the cross bars.