Looking at your photo it seems that the metal strip has been fitted to hide/cover the step and wouldnt provide a good weather seal to the door(i might be wrong).
If you do a google search for 'STORMGUARD' then this will show you what i usually fit on timber doors that i hang.
NOTE TO MODS: I am in no way connected to anything to do with this company,i am just informing Dan as to which weather seal i use.Thanks.
It's not a seal, its just a cover to protect the timber cill. You could knock that one up from some aluminum sheet, or buy a pre-formed brass or s.steel one.
For a threshold seal (to stop the water getting under the door) see the www.stormguard.co.uk site
Or fit a weather bar and rebate the bottom of the door
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