You set up a nice tone in the poem, dark without being angst-ridden.

Punctation (since you asked) -

Line 11 should end in a comma instead of a semi-colon. If you don't want to use a comma, a colon would also work. Semi-colons separate phrases that could be independent sentences.

L13 - It's a sentence fragment. Sometimes they're useful to drive home a point, but I think placing a comma at the end of the line and tying the phrase into the next sentence would work better.

L16 - Same as L11.

I'm a stickler in some areas: if you're going to punctuate the poem, besides a very occasional period or question mark, ya might as well do it right. :-)

Nitpicks:

In L3, I'd put a definite article:

from the tar paper roof above

I took the drips to be outside the house, but maybe it would be clearer if you said:

dripping..... dripping.... dripping
off the tar paper roof

L4-5 You use the word "in" 3 times in 2 lines. It doesn't quite hit me right. I'd change one of the instances to another preposition:

to gather in oily puddles in hollows
worn from tired steps by generations

Hope this helps,

Cres

(Sigh, must remember to preview post when playing with html!)