Railings for 2nd Story- Necessary?

Yes put some sort of railing up. As far as a safe jumping height I wouldn't make them jump too far down at all, they can get hurt easily.

Thank you. I think I am going bend grids to make about 8in high sides for 2nd story. I'm going to make a ramp down to the top of the piggie house. That leaves about 8in to hop down. If I get small piggies I will probably add a ramp to the top of the house.

I can't wait to get the cage built so I can start searching for my piggies! I'm going to adopt a pair of girls.

Here's a picture of my cage that I recently re-did. It's hard to see but on the far right side there is a ramp which leads to another grid(that has been zip tied to the cage) covered with coroplast and then another ramp leads to the 2nd floor. I did this because it took up less floor space and made the ramps less steep. If I were you I would have a ramp at the bottom either from the house going down or use a grid like I did. 8 inches could be quite a ways to jump down especially if you get young pigs. Pigs can jump, no doubt but when they are running at full piggy speed there is a possibility that they could jump off too fast and get hurt.
Good luck with the cage building and search for pigs. If you need help finding pigs let us know what area you are in and I am sure people will be more than happy to help!

Thanks for all the help. I totally changed how I have the second story set up. My cage is 3 grids long by 2 1/2 deep. The second story is 1 grid deep along the 3 grid wall. I made a switch back staircase along the 2 1/2 grid wall. The stair case drops down with a 3 grid slope then hits a landing at 1/2 grid height and then drops down the rest of the way with another slope. The ramp is covered with carpet. I use this ramp as a guide.

As for guinea pigs, the local ASPCA has several girls. They will be up for adoption as soon as they are sure the piggies aren't pregnant. I can't wait!

My second level is just mattress pads and fleece so I do not use coroplast up there. I cut the grids in half and used them for the front wall of the second level. You need a really good pair of metal cutters and a metal file to file off sharp edges but it was worth it.

This is the pic I have (sorry it's pretty blurry)