Lay more 2 by 4s on either side of the tarp and attach those as well for a tight well secured water barrier.
Using tarp to cover roof.
The 2 by 4 should be about 2 feet longer than the tarp width.
However not all jobs can be completed in one go and the crew will need to return to complete everything.
Partially unroll your tarp to cover the damaged area from the roof s eaves to peak.
Create an anchor board by rolling the tarp s peak end with a 2 x 4 inch board and nailing the tarp to your board with.
Many residential roofing jobs can be completed in one day this of course is assuming that the roof is not steep sloped extraordinarily large and that the crew is made up of experienced roofers.
Screw the 2 by 4 directly into the roof to secure it.
Then fold the excess tarp under a few rotations for a tight clean fit.
There should be an additional 4 feet.