Herringbone Parquet Question

[Joeymac]

Hi all.

I am restoring some parquet flooring at home and I have a question if I may.

My lounge leads into an extension and under the carpets there is a nice herringbone floor, but in the extension bit it is screed. I travelled far to buy some reclaimed parquet but it was 5mm wider than advertised. I bought it anyway. My question is would you cut 5mm off the new blocks and break into the existing pattern or would you start a new square, 2 block border pattern in the extension area? I have attached some photos, one of the pattern and one of the extension area in the longue. I hope I'm making sense. Any help is much appreciated

 

[Joeymac]

I should also mention that both the existing blocks and the ones I bought are tongue and groove, so if I did cut them down I would lose the t&g.. im no expert but it would still be ok to simply glue them down without t&g right ?