[AVPIV]

I am in the middle of a remodel in seattle and have a six 6 diameter exhaust vent for my furnace that currently runs up through the roof. My question is can I re-route the vent through the floor to vent out the side of the house instead of through the roof?

 

[hvaclover]

Being six inch I have to assume you mean a metal chimney. No you can't vent out the side with out a specialized motor driven fan system

 

[sktn77a]

You could do this, if you absolutely must, but you would need a double wall galvanised vent pipe and an exterior power venter. Unless you positively, absolutely, must go this direction, I would avoid it as the external power venters are expensive and unreliable.