I bought my house last spring and got started on the lawn in early summer. (Had remodeling to do). I tore down two structures in the back yard and planted some grass where they were. Just as the grass was coming in nicely, it got choked out by crabgrass.
Since I noticed some grading issues (water pooling) last year as well, I'd like to till up the whole yard and grade it properly, then plant seed or sod. (The existing grass is spotty at best also). My questions:
1. If I till up the yard and plant seed, will the crabgrass just take over again since I can't put down crabgrass preventer with new seed?
2. If I till up the yard and sod, will the crabgrass just grow through the sod and take over?
3. Can I just spray Roundup or something to kill all the existing plant life will it stop crabgrass from germinating?
If option 3 will work, I will do that this weekend (pending response) and then till up the yard in two weeks when I get back from vacation. SKIING!!!
I have two dogs so I am assuming that sod is the way to go. How long after putting down sod would it be safe for the dogs to use they yard again? If sod / seed makes no difference, I will just fence off half of the yard for a month to let new grass grow and then do the same on the other side.
Sorry for the long post. What do you think?
Your post is fine, not too long at all. Welcome to the forum! 
I haven't planted lawn for years, but as I recall, I put down the crabgrass preventative and waited the prescribed time before sowing the grass seed.
I also have dogs, and I used temporary fencing to keep them off the newly planted area. I think I left it up until I had mowed the new grass 3 or 4 times. It may not be necessary to wait that long, but I felt that was the point at which the lawn looked like it could withstand the traffic of the dogs running on it.
I haven't planted lawn for years, but as I recall, I put down the crabgrass preventative and waited the prescribed time before sowing the grass seed.
I also have dogs, and I used temporary fencing to keep them off the newly planted area. I think I left it up until I had mowed the new grass 3 or 4 times. It may not be necessary to wait that long, but I felt that was the point at which the lawn looked like it could withstand the traffic of the dogs running on it.