Mist yards have panel saws and will make some number of cuts free or cheap.
Carry plywood roof rack.
Place a shim a wedge shaped piece of wood or any thin scrap wood in the gap between the foot and the cross member and drive one screw through the cross member nearest the point where the foot and cross member touch but at least 1 2 inch from the edge of the wood.
But there are some ways to keep the plywood stable.
Diy roof rack for car without rails ideas it is bare as it rests on the roof and is clamped on the door openings and very effective in carrying kayaks.
Never haul sheet goods or mattresses.
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.
Install a proper roof rack secure strongly to that without exceeding it s cargo rating consider a leading airfoil and drive slow.
While you can get away with carrying two or three sheets of plywood on your roof rack as the load gets larger the chances for rack failure or broken straps increase.
A bare roof can t carry a load because it can t distribute the weight out to the pillars and door frames.
Take the bike kayak carriers off and strap it directly on the rails you ll be fine.
Find out what the rating is i think mine is 200 lbs.
In case your car has a roof rack it will be even simpler.
A pair of 20 web ratchets used as a fail safe in case the board slides to the rear of the vehicle.
Normally its white daunting to carry skis but the ski roof rack simplifies it allows both skis and snowboards to be carried effectively.
Heh a yakima rack can carry many sheets of plywood just fine.
Some people may worry that the size of the rack is not big enough to cover the sheet.
On a roof rack.
Here is a step by step process you may want to take a look if you want to make good use of the roof rack.
If you are fortunate enough to have a full sized truck where you can lay a full sized sheet of plywood on the floor in between the wheel wells then this vide.
I do it all the time.
My car with 4 x8 mdf board on the roof rack.
If you place a load on a bare roof you ll damage it.
Place the plywood sheets on your roof rack.
Second trip 16 2 x4 x6 boards on my roof rack.
Or ttpransport plywood inside the vehicle.
Do not use a car for any load larger than two or three sheets.