WE generally install tile at all basement entrances. As for the exterior door a goo elastomeric sealant is Geocel 2300 clear. apply a thick bead at threshold outside door.

Thanks. Since for rest of the basement we are thinking dricore+carpet, can the entrance tiles be installed on the dricore? Otherwise how would we level them with rest of the floor?

the tile needas to be on a concrete base on concrete backer board. It would be possible to have a thick bed of mortar with 1/2" backer board then a thick mortar bed again with tile on top. This is a little un-orthodox. Why are you using the dri-core under the carpet???
Tom

I just completed my basement with dricore installation thru-out and had put in 12X12 natural stone tiles (travertine) at the entranceway-carpet elsewhere.

I took an unorthodox approach in ramsetting the dricore panels securely to the floor first and then used Flexbond (a fortified thin-set mortar) to bond the tile onto the dricore panel. I was liberal in applying the mortar onto the dricore panel to offset any slight differences in height from 1 panel to the next.

What sold me on Flexbond was the statement "Isolates cracks up to 1/16" and withstands minor substrate deflection" on the package, and also spending additional $$ on backer cement boards.

So far I'm please with the result but YMMV.

It may also helps that I was going for an antiquity look so my tumbled tiles do not hv any grout joint.

Here is a link that might be useful: Flexbond info