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2Edwardian semis single storey extensions with different roof pitches

Anonymous user 28/02/2024 - 3.53 PM

We are building a single storey rear extension wall next to our neighbour’s single storey rear extension wall The neighbour has a pre-finished aluminium capping to their parapet. We intend to form a pitched roof abutting right up to theirs forming a weathering detail - but this is proving decidedly difficult! Our roof pitch will not match theirs. Their roof pitch I estimate is 12 degrees and ours, 15 degrees. So there is a cross over. He has a lower pitch as his roof is glass, Therefore, the lowest part of our roof at wall plate level does not enable a 150mm cover flashing to be formed between the neighbours extension wall and our roof (we can only get say 60-70mm upstand). At the highest level at rear original house external wall abutment, there is healthy say 300-400mm difference in levels down to their parapet which would enable a detail to be created (subject to their agreement) dressing on to their parapet. But the ‘cross over’ space between the two creates a troublesome area difficult to weather properly. It is not really an option to take off the neighbour’s aluminium capping. I understand an option is to form my own parapet which would resolve the issue, but I may lose internal floor space. Any ideas?