Place the wood on the floor or ground and hold in place with small screws.
How to install temporary roof supports.
The ideal height of such beams should be 2 10 foot longer than the distance between the roof and the ground.
Use 2 inch carriage bolts to secure the posts to the mounting brackets.
Attaching the two with bolts every foot or two 50 cm.
The temporary support that you use will need to have a firm footing in order to hold up the weight.
Bring in a sledgehammer and insert some wooden pieces into the ground.
Make sure that the beams support the roof well and are not left loose or wobbling.
Once it is plumb mark the position on the porch roof.
I did not interpret your question as whether to support the open web joist on their top or bottom chord.
We provide a nationwide installation service supplying to a broad customer base our shrink wrap encapsulation system for their projects.
I would never install temporary shoring of open web joists on their bottom chord.
If the ground area is hard and difficult to penetrate then you can go for an alternate solution.
These pieces act as the bases that hold the legs of the support beams.
For a perpendicular support you should use square pieces of 3 4 inch plywood or other scraps of wood that are at least 10 inches wide.
Vertical shoring against the top chord of the joist is most certainly the least expensive choice.
Stand a post up in the bracket and hold a level on its side.
Once both of the brackets are secured set a post into them.
Install another bracket in this position.
Continue installing porch roof supports.