who is responsible

What is the name of your state? tx

who is responsible for poor workmanship, the general contractor or sub-contractor who performed the job.

As in lawsuit? Sue them both. As in getting it fixed, as in new construction, as in how old is the construction....and on and on. In other words some details might help.

the construction is brand new. THe deck that was poured lacks proper drainage and potentially has caused home to flood

In TX all builder complaints must go thru the Texas Residential Construction Commission now: http://www.trcc.state.tx.us/ From what I have heard/read, it's more builder-friendly than consumer-friendly. Google the agency's name and you should find lots of news on it.