Lay more 2 by 4s on either side of the tarp and attach those as well for a tight well secured water barrier.
How to secure a tarp on the roof.
On a shingled roof you just nail the tarp in place using furring strips but you can not nail a tarp into a tile roof.
Stretch a tarp flat on the roof.
Once every grommet has a bent nail in it add a dab of roofing tar into each grommet hole around the nail that penetrates the roof to protect against leaks.
To secure a tarp to your roof.
Positions several 1 2 pieces of lumber on the tarp running vertically down the slope of the roof.
Then fold the excess tarp under a few rotations for a tight clean fit.
Never lay the tarp out during a storm.
Screw the 2 by 4 directly into the roof to secure it.
You want to get long 3 inch nails to get plenty of bite into the roof s sheathing and still be able to bend an upper portion of them to secure the tarp.
It is best to also weight the tarp down with sandbags or heavy objects to keep wind from blowing up under it.
Find the source of the roof leak.
Let the rest of the tarp hang off the lower border of the roof that overhangs the wall known as the eave.
Wrap the tarp three or four times around the wood then secure the wood to the soffit or the roof deck on the side of the peak opposite the side that is leaking.
Extend the top edge of the tarp over the ridge of the roof.
Lay the tarp out flat over the roof.
If required cut plywood as needed cover up any existing penetrations with plywood secure the perimeter with screws every 6 to 12 into the roof sheathing below preferably into trusses unroll the full tarp make sure that the length extends 1 past the edge of the roof on the damaged side.
This will prevent water and debris from entering the damaged area.
Pull the other end of the tarp over the peak and down the roof far enough to cover the leak then secure that end to another 2 by 4.
The 2 by 4 should be about 2 feet longer than the tarp width.
You can use 2 3 inch wide double sided tape to secure the tarp to the tile.
To begin securing the tarp screw through the rolled 2 x 4 boards with your screw gun.
The screws must pass securely into the roof.