No reason to not go through the joist. If this is just in a crawl space not a basement then just go under the joist.
I mentioned expansion loops only because I found several reports online of plumbers being dinged by the building inspector for not using them, even on potable lines.I assume you are talking about potable water, not PEX for heating. Potable water is rarely set hotter than 125 degrees F, occasionally I have seen 130 degrees F, versus hot water heat that can be 160 degrees, occasionally hotter. There is very little expansion of PEX at 125 degrees, so the hole through the joists can be slightly larger than the PEX, say 1/8 inch larger. If in any doubt, simply drop a short length of PEX into hot water, it will expand to whatever its final dimension will be very quickly, and you can test how large a hole you need.
As to the allowable dimensions for holes in joists, they are the same whether you are running wire, tubing, or just like to put holes in your joists. For 3/4 inch PEX, a 7/8 inch hole near the midpoint top to bottom of the joist should be OK, but you may want to use 1 inch to make it easier to pull. I have a fair amount of PEX run exactly that way in my basement. You can of course hang the PEX from the joists, or put it between joists if it goes that way, but if you are perpendicular to the joists and you want to hide the PEX a little, joist holes work well.
I had seen those pex supports and wondered about them. Seems like putting multiple 1 3/8 inch holes in every joist though would weaken them at least a little.I use 1 3/8 holes for water piping up to 1"
Then I use these in the hole after the pipe is in. Wrap them over the pipe and pound them into the hole- thats why us plumbers call them pound-ins :laughing:
When I started apprenticing over 20yrs ago my jman handed me a hole hawg with a 1 3/8 bit(we call them water bits) and said go dill out the 3rd floor of that apartment complex. Been using one ever since.Are those inserts required by Code for joist penetration? It seems to me that the smooth hole left behind by a hole saw would be no rougher than the inside of those inserts. Why not let the joist support the pex on its own?
That way a smaller hole could be used (?)
My thoughts exactly. I was worried about weakening it.I had seen those pex supports and wondered about them. Seems like putting multiple 1 3/8 inch holes in every joist though would weaken them at least a little.