Video shows how the extension comes so close to Stuart Smith's home the houses are separated by just eight inches meaning he cannot access that side of the property. Mr Smith, 42, has branded the construction work "bizarre".
Speaking to Birmingham Live, the NHS worker said: "It's come over the boundary on the same land - effectively you have two buildings occupying the same space. It's like a catalogue of errors right the way across.
"It's been built so far over the boundary line onto our side there's no gap to be able to maintain our own property.
"We can never remove the gutters now, we can't unfix the felt roof, or the fascias or render the side of the house. It's like that permanently and any problems we'll have to live with."
Mr Smith, who lives in Kings Norton, Birmingham, where the average house price is around £190,000, alleged plans were not followed as builders were unable to properly fit a roof on his neighbour's home, so a wall was built just beneath his roof and stepped in.Insurance Loans Mortgage Attorney Credit Lawyer
He claimed the "catalogue of errors" across the boundary line meant guttering attached to the properties touched, leaving him worried about drainage and damp issues.
Planning officers for Birmingham City Council are now probing the extension, which saw works carried out over a garage to increase the property size from three to five bedrooms.
Stuart Smith is angry over the line and extension of the property next door to his (Image: Darren Quinton/Birmingham Live)
"They (the builders) didn't actually realise their mistake until they started building underneath my eaves. It was only when they got so far up they realised my roof was in the way of them putting their own roof on," added Mr Smith, who works in IT for Birmingham and Solihull Mental Health Foundation Trust.
"I did speak to the neighbour at that point and they said they would 'sort it out', but (the builders) didn't fix it, they just worked around it, recessed it in, built a little flat roof and built the roof to the side."
Mr Smith, married to nursery teacher Sallyanne, 39, said works started at the end in January 2021, when they were woken up by loud banging as builders began the foundations.
The key workers, who have worked tirelessly throughout the pandemic, said it was not until March that they could see the top of the building.
Mr Smith, who works for NHS, said he is unable to access the side of