Get at least three quotes for each, but be sure you've developed a precise scope of work for the rehab and build specs for the new construction, right down to the number and location of electrical outlets and what kind of doorbell will be installed. 

Here are the specs:6 unit brick multifamily Apt building-priced at 569,000- negotiated down from asking 600,0006-2bd/1bth apts currently does 4700 per mth-rent currently about 20% under market at the start of due diligence was 100% occupied-That is what I based my offer on building performing at 100%tenant just gave his 30 day notice -so before closing the building will have 1 vacancy performing at 84%The inspection also turned up 15k of safety violations I believe both are points of renegotiation-I'm just not sure how much is my question-I was going to ask for 15k of a closing concession to cover the safety issues-but how much is considered acceptable/reasonable to decrease the price for the vacancy?

I am intending to list one or more houses to be built, and line up a buyer with a construction loan, as opposed to doing a spec build and incurring the additional costs of funding the construction.

Are you wanting to fund spec new construction?

Capacity, solar panels brand and type, battery back-up if so, etc? 

My man @Yonah Weiss's company Madison SPECS did a cost segregation study on one of my properties. 

-Specs: 3 bed, 1bath in Bristol CT1,095 sq ftIt has another lot attached to it, I believe behind the property, I'm going to see it this Saturday-Taxes: ~2500/yr (this doesn't include the other lot, I need to ask what he pays for them both)-Initial home offer: 150,000 (defenitely could talk him down)Needs a 15k down payment (nothing lower)-Estimated rent:1200 if rented as one unit I'm considering piecing out the rooms, might be able to get 14-1500 that wayAs it stands at that price and a normal 30 yr fixed rate at 4% and money set aside for capex, maintenance etc, the deal is losing about 50 bucks a month, however this is a seller finance and a lot of numbers can be worked on.I'm thinking of offering 125,000 (before 15k down) with a a 40 yr fixed rate at, maybe at a little under 4%, these numbers look better, leaves a little over 150 dollars in my pocket and a little over 10% Cash on cash return.Do you think this is a reasonable offer to make in such a situation?

Ensure all smoke detectors are accounted for and have a working battery.

I have built many houses. both spec houses, and custom homes.

It's battery operated and you program a code.