Experts say the case is not unusual and Mr Davis says he and Sumi King have done nothing wrong.
Mr Alwahb said he had no idea about the demolition plans until the pair knocked on his door.
"They told me that they are going to demolish their side and that everything is consented. When I asked when, they said soon, in a few days or a week."
The pair plan to demolish their side of the property and preliminary plans for the replacement show a cascading, three-box house.
Mr Alwahb said he asked them why they hadn't told him sooner, and says they just responded that everything had gained council consent.
"I asked what options did I have and they said, 'Sell, demolish your side or weatherboard [the exposed side]'. I said, 'This is my house, my home', and that I have family and they said this was going to happen and that the Auckland Council has consented to it."
Mr Alwahb, who has custody of his children at the weekends, is concerned that the demolition and excavation work could result in subsidence to his property.
Mr Davis told the Herald no deadline had been set for construction to begin. He was surprised Mr Alwahb thought demolition would commence in the next week or two.
He confirmed that under current plans, the shared side of the house would become exposed and require cladding, but would not be drawn on whether he and Sumi King would foot the bill.
Mr Davis declined to comment on why they hadn't notified Mr Alwahb sooner, saying the matter was private and they had done nothing wrong.
The council's resource consent decision confirms that the site is "subject to instability".
However, Jeff Fahrensohn, council manager of inspections and building control, said the Building Act 2004 protected neighbouring properties from damage and the proposed work was specifically designed to do this.
If the council believed at any point during construction that Mr Alwahb's house could be damaged, an inspector could issue a "notice to fix" requiring necessary repairs.
"The house at 74 will be removed piece by piece, and structural supports will be put in place to support the existing building. The work is required to be carried out under the supervision of both structural and geotechnical engineers, and the work inspected by council inspectors at key stages," Mr Fahrensohn said.
As for notification, he said that while contacting neighbours was not a formal requirement, "we would expect that as a common courtesy, anyone wanting to do construction work is talking to their neighbours about their proposal".
John Gray, of the Home Owners and Buyers Association, said such predicaments were quite common, but the success rate was varied.
As the property was freehold there weren't the protections of a cross lease, which imposed specific obligations and duties on owners.
"It strikes at a void in the process, that this sort of thing can go through to this extent without there being any formal consideration by the authorities of the effects of this work on the adjoining unit."
