Hello all. Redoing bathroom floor and peeled up old linoleum and plywood floor that was covering the cement slab and found a large hole in cement. Under a very old beam you can see my bathroom sink pipes under it heading towards the tub and then heading out in a teeny crawl space towards the actual stonewall basement. House was built in late 1700s and then the back side of the house was added onto much later with a concrete pad. Sink is working fine but how do I protect the pipes when I pour in cement to cover up the 13 by 13 inch defect. It appears that there must have been an old sink that was capped off and moved back more. I am going to have a person skilled in tile do the floor but clearly need to fix the hole. I am obviously worried about what happens in the future if the pipes leak but with this poor excuse for a house my motto is if it isn't broke don't fix it! Thanks for any advice. Do I cover it with tiny wire mesh or pressure treated plywood and then fill the rest with concrete? I am stumped.