4 web ratchet straps in a pair of x formations to hold down the board to the cross bars.
Strapping lumber to roof rack.
That prevents the bundle from sliding forward backward or side to side.
On each side of the roof you ll see a rack that runs the length of the roof of the vehicle.
Next secure the load to the rack using ratchet straps photo 2.
Thread the strap end through the buckle and pull.
Start by loading dimensional lumber onto the rack with the narrow edges resting on the crossbars.
A pair of 20 web ratchets used as a fail safe in case the board slides to the rear of the vehicle.
Wrap the strap around the load and under and around each rack.
Use a tie down that wraps around the item and the rails.
My car with roof rack with cross bars installed.
Acquire ropes and straps.
Then secure the front and back ends of each lumber bundle with ratchet straps to prevent movement photo 1.
Wood recommends a webbing strap with a fastening buckle that.
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.
The second option is the side racks.
My car with 4 x8 mdf board on the roof rack.