Never one to resist a troll-heavy discussion, chiming in where I'm not wanted, I did have a chance to check out the film last night. I enjoyed it a lot, though I didn't really laugh. I found it more "amusing" than "funny", but pleasantly so. I don't really like comedy, so that I enjoyed it says a lot. I do like this style of humor much more than, say, sitcom humor, for what it's worth.
Thinking about what you could have done differently/improved on for you next, I think it could have been faster and more absurd. You've already got an absurd situation (who throws away a full sheet of drywall!) and a good comic character (someone who feels the need to "get one over" on his neighbor past all reason). However, it felt like there were too few obstacles to overcome, and each one took too long. If there were more absurd challenges and paced so that the scenes became faster and faster, I think it would have been funnier.
For example (note: I am a musician, not a writer, and not particularly funny at that, but I like to think about stuff)
-drags the sheetrock (take about the same time that you did)
-sees the line, goes for the hose
-hose doesn't reach the street, goes to garage for extension
-his extension is gone, with a note from a neighbor who borrowed it
-because he doesn't want anyone to know what he's doing, goes to another neighbors house to steal a hose to use an extension
-gets the hose, and the automated sprinklers come on (bit of slapstick)
-attaches hose, only partially washes off, like you have (the hose he stole wasn't as long as he had thought)
-gets chalk. Either searching at home, like you have, should be much shorter, or another more absurd way of getting it. Stealing from a kid playing on the street maybe? Either way, the pace and edits should be picking way up at this point.
Cutting away to the neighbor driving at a leisurely pace every once in a while would have added tension as well. More tension==more chance for comedy.
Overall, I did enjoy your film. I think you've got the foundations down to build some good stuff. Looking forward to seeing your next one!
And now I want to rewatch The Burbs!