Plumbing – How to cover area under vanity with PEX exposed

bathroominsulationplumbing

I just installed IKEA vanity and it requires re-run new PEX. Since behind the wall is concrete at corner wall, only way is to run PEX outside the 2×4 like picture below.

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But now it opens a hole like that and sometime I can feel wind blow into it since the left side is the garage.

And it’s not simple to cover with drywall as the pex is in the way.

What are my options?

  1. Just stuck some insulation behind the 2×4 and prevent wind blow into it

  2. Duck tape or some kind of thin panel?

  3. Make a “box” extruding outside. This is complicated as I have to deal with clearance from the ikea drawers

Best Answer

Get some fireblocking foam and fill the hole

Since the thing on the other side of the wall with the hole in it is your garage, IRC R302.5.3 kicks in, which requires penetrations in the house-garage wall to be sealed in accordance with R302.11, item 4, which in turn requires an approved fireblocking material to be used for the job, albeit not necessarily something fully tested for firestopping (as you'd find in a commercial or institutional building). Most jurisdictions will accept a garden-variety fireblocking spray foam for this job; these materials form a char layer on their surface that cuts off their innards from further combustion, thus keeping the fire from getting to the other side for a little while.