Use this figure for your roads, water, sewer, electric.Just making the following up:Road- 25 ft wide, 6 inches thick, before curbs. 

.• install a vapor barrier with a minimum of 12 mm thickness• paint the inside of the crawl brick with dry lock paint•install a dehumidifier and sump pump• insulate the floor as there is no floor insulation currently in the crawlspace (how necessary is this?)

Increasing the thickness of the drywall means there are at least two areas where the density disrupts the waves a bit more than normal. quite rock qorks because the material makes it harder for the wave to transfer not simply because it is thicker. 

Michael,i appreciate the response thank you.just to be clear, I have thick skin, been doing large scale construction for 23 years and transactions totalling in excess of $200mm but it just caught me by surprise in one of the forums when someone had asked about a investment property str and it was a vague question and got a "holier than thou" response and when they responded back they essentially reduced the person to a you tube investor lol.

Our Hispanics they work through thick and thin with some being the owners of the company but most are skilled labor  and they are very skilled and do excellent work.

That's always 1 1/4 in. for every bathrooom drain, you only get it to 1 1/2 in. past that point with a thick slipjoint washer.