Chin-ups are arguably the best upper body resistance exercise around. There is no other exercise that can replace its functional value; and no, the lat pull down is a not a suitable replacement. Not only do chins build the back and biceps, the abdominals, chest and grip get a workout as well.
A chin-up bar in a gym is also a highly useful fixture, given that it can also be used as an anchor for rings, bands or a TRX.
Fitness Nutrition is not responsible for the integrity of the installation. Seek advice from the appropriate professionals as to the structural strength of the wall you are assembling to. Failure to install correctly could result in serious injury!