Question on running numerous PEX runs through floor joists

[ajs317]

I'm working on a project to replace the monoflow piping in my basement, which connects to in-wall convector units with finned tube copper in each room of the house. I'm planning on replacing the copper piping and the zone controls currently in multiple locations with 1/2" PEX home runs to a manifold next to my boiler in the basement. Because of where the boiler is located and because the manifold will basically be branching out to every room in my house, I will have a few places in the floor joists nearest the manifold where I will need to drill a number of holes (6-8 sets of supply and return so 12-14 PEX runs total) before the runs start turning off in different directions to go up into the rooms. Running the PEX underneath the joists isn't a preferred option because I'll be finishing the basement ceiling.

I'm aware of the guidelines/code requirements for drilling floor joists, but is there any reason for concern about the total number of holes in the same area if those guidelines are followed? For example, could I have two rows of 6 or 8 holes on top of each other if the holes are spaced out 2" from one another? Or is there a concern with having just too many holes in one area, even if the holes are all in the middle part of the joist and slightly separated from one another?

 

[Terry]

Why not fewer holes and bundle the lines together?

A floor joists needs 2" on the bottom, 2" on the top, and no more than 1/3" of depth for the hole.

 

[Sponsor]

 

[ajs317]

Hi Terry, no reason I couldn't do that. Is fewer larger holes better than more smaller holes? I suppose one drawback would be that you couldn't use those premade abrasion clips that clip around the pipe and sit in the joist hole, but maybe there's another way to protect the PEX where it crosses.

 

[Terry]

maybe there's another way to protect the PEX where it crosses.

Those clips are mainly for support and for water hammer where the pipe jumps after shutoff. Floor joists are very 16" anyway, and with everything touching, I don't see them moving much.

 

[Bill Doh]

Terry, how do you usually bundle the PEX tubing? I have a home run with 5 hot and 9 cold 1/2” tubes exiting the Manabloc together to one side of the house. This is my first time doing this. Is there a best way to bundle the tubing? I plan to bundle 3 cold tubes in 3 holes and Bundle the 5 hot tubes in 2 holes (3 and 2). It looks like I have enough room to drill the holes 3 inches apart...staying in the middle of the joists, as you mention above. Is there a best way to design the bundles? Thanks!