Wood rot around door

[aidanh]

I have some wood that needs replaced due to rotting at my back door. One piece of wood seems to be 34mm x 54mm, I had hoped this would be a standard size that I could pick up from B&Q but while 34mm seems common I haven't found any that are 54mm. Any idea if this is something I could by somewhere? or will I need to get it cut?

Thanks

 

[big-all]

picture off the actual bit off wood will help as it may be a packing piece or part off the door frame which can be different materials[hard/soft wood]

 

[aidanh]

Thanks, here you go -

 

[big-all]

a wood yard should run it up for you but at a cost as it would be from ex 3x2"
2x1 [51x25.4mm]treated and 12mm ply comes out about 11.7mm would give you 51x 37.1mm
or 2x1 [44x21mm] planed and 12mm=11.7=x32.7mm
but require a sawing to size