We have a Cape home built in the 1970's. The entry way door sills are in sad shape. What will it take to replace them? Is it something we can tackle ourselves or will we need professional help?
You never know what you'll find util you dig in and get started. What is the floor? If concrete the job should be pretty easy. If it's wood and there is water damage then you may need help. Can the sill be removed without being destroyed? If yes, pull it up and see what's under it. Can you post some pictures? That would be a great help.
I think you mean threshold. Click on "How-to & Repair" at the top of the page, then click on Doors in the list, go down to "Replacing a Threshold" click on it and watch a video of Tommy Silva replacing a threshold. You can watch other videos also.