Replacing 1930s front door threshold/base

[Sprocker]

Hi
I was hoping someone could advise me on best way to replace the threshold base (not sure what it's called!) on my front door as it's really rotten, also what type of wood would I need, pretty sure its currenty original to the house atm so would like to replace with something similar so it lasts! I've attached a few pictures so you no what I'm talking about
Thank you in advance!!!!

 

[Sprocker]

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[Sprocker]

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[foxhole]

You can replace with a hardwood threshold, will take a bit of removing as its probably built into frame.Cut straight thru the middle then swing it left and right until free.May be some nails in corners to cut out.If you can't find threshhold to fit it's fairly straitforward to create from a length of suitable timber.Make sure new is fully treated before install.

 

[Sprocker]

Ok that's great thank you, what is a suitable timber, also there is a void underneath the threshold atm should I level with some sand and let the new bar sit on the top? sorry for the questions I'm very new to DIY!!

 

[foxhole]

Depends what you find underneath , may need building up ( brickwork ) as the void is going to let in moisture.
As mention needs a hardwood threshold .