There were doormats in front of various deckhouse doorways. See various photographs of the Titanic like the Father Browne collection. We are not sure of the exact amount on the Titanic but we placed at least 28 of them on our models in the more visible areas about the Boat Deck, A deck fore/aft, and B deck fore/aft.

Parts required:

CONSTRUCTING THE MATS

Step 1. Use the planked Evergreen sheet plastic. Cut a 3mm wide x 56mm long strip along a square end of the plastic cutting ACROSS the planks. Use an extremely sharp hobby knife (new blade recommended) and a ruler (or other device like a small craftsperson's T square).
Step 2. Now cut across the plastic strip at every 3rd plank. Repeat this along the entire length. The end result should be 28 ribbed rectangles with the ribs (planks) running 3mm wide and 2mm long.

Step 3. Make a small loop of masking tape with the sticky side out and place it on the table in a position that is easy for you to paint on or attach it to a small square of sheet plastic so you can rotate them.
Step 4. Press each of the mats randomly onto the sticky tape surface in a manner that will allow you to paint their tops and four edges all at once.
Step 5. Paint them the color of your choice. We used Testor's Military Flat Brown for ours so they stood out slightly from the deck's color
Step 6. When dry dab a bead of glue at the base of each door where you want to place a mat. Glue a couple of doors at a time as the tiny beads of glue dry fast. You do not want to use too much glue or it will squeeze out from the bottom and mar the deck needlessly. ALWAYS USE THE SMALLEST AMOUNT OF GLUE YOU CAN GET AWAY WITH!! Place the mats in front of the doors on the Boat deck and A & B decks forward and aft. You can add more along the promenade deck if you wish to (we elected NOT to).
Step 7. After the paint has dried peel the mats from the tape with tweezers or your fingers and place it neatly on top of the bead of glue. Use the tip of your hobby knife to push it up and against the bottoms of the doors and straighten them out. Repeat this process for all the doors you want to have mats.

SEGMENT ENDNOTES

A & B Decks:

Place A and B deck mats on before you glue the decks together otherwise you will have a much harder time lining them up through the promenade railings and/or other recessed areas.

But what IF...

If you already have your model built but wish to add these recessed mats, then use the GluSquito to dab a bead of glue at the base of the door between the promenade stanchions (for example) and then dab a toothpick to your mouth and pick up the mat with the spit/toothpick combo on the painted side. Next squeeze the toothpick between the stanchions and touch the mat to the glue bead. When you withdraw the toothpick, the bead of glue should pull the mat off into its relative position. If needed, then use the smallest point of the (wooden) toothpick to adjust the mat to be flush with the door in that it is both centered and parallel to the wall and door opening.

The method works. Perhaps not the most sanitary way of doing business but it does allow retrofitting parts for models that have already past the point of the easiest assembly methods.

Boat Deck:

Place Boat deck mats on after the deckhouses are mounted.