Originally Posted by email@example.com
Sorry for the delay in responding... busy. I think the existing shelves are made of "project panel" (Lowe's). Basically a pressboard of some type and not plywood. They are 3/4'" thick. The existing shelves would probably not be horribly difficult to remove but I think the homeowner would rather not go that route. At the rear of the shelves they rest on a pine ledger attached to the wall and is 3/4" thick. The front end is supported by vertical pieces that run from floor to top shelf. The ends of the existing shelves that I need to attach the new shelves to overlaps the vertical support by about 3 inches. Without dismantling the old shelves I don't see how to cut them halfway back into the vertical support where I could then attach the new shelf as well.
Pressboard is not easy to work with. It flakes, breaks, chips and is not really conducive to working with other real wood.
But I am prejudice as I always have hated that stuff.
If you keep that particle board in there and just add more wood to extend the shelf there isn't much you can to do make a secure connection. I suppose you could just butt the new wood up the old stuff and make sure that it is secure in the front so the wood doesn't move forward and cause a separation in the back.
I suggest a support in the middle as particle board is not known for it's phenomenal strength.