There are no assembly nor plumbing instructions required for this vanity. We try and keep our models simple for our customers. The drawer has a u-shape cut out to allow for plumbing. The back is enclosed but the bottom is completely open. If you need specific measurements for anything, please do let me know as I'm happy to help. Thank you kindly and have a lovely day! Regards, Olivia with RFDesign

Please confirm then if measured for plumbing it would be accurate center if the 36” cabinet.

Good Morning. The faucet hole and drain opening is dead center. The vanity actually measures 36 1/4" wide putting the center of these holes at 18 1/8". The vanity body is 19.5" from the ground. The drain opening is 27" off the ground (bottom of sink). If your plumber requires any additional information, please do not hesitate to ask as we are happy to help. Thank you again for your purchase and have a lovely day! Regards, Olivia with RFDesign

My plumber is having a problem keeping the sink for leaking because he says the hole is not completely flat and the drain piece does not sit flush. Is there anything to do to correct this. He has tried several different types of caulk and nothing has worked

HI Lisa. Sorry to hear you are having issues. I'm having a hard time grasping how a hole in a flat marble top cannot be flat. I'm firing in the dark without photos showing the issue. We've sold 100's of these vanities and we've never have been reported an issue such as this. I'm not saying it's not possible just struggling to understand. Please send photos and we are happy to share with our local stone mason for input. Thank you kindly and look forward to hearing back from you. We certainly want satisfied customers. Have a lovely day! Regards, Olivia with RFDesign