hi Randomx, the bearers sit on the stumps and the joists sit on top of the bearers but in the opposite direction, so if these were brand new then there's a chance they will shrink and fix the problem on its own, so just to make sure what I'm saying, have you made this into another deck or room?
A weather shield fitted to your door might help, that is when you open your door the w/shield that's attached to the front bottom on the outside of your door will stop water getting.
These shields can be adjusted by moving the little round ball with one hole in it, about the size of 5c piece, which is screwed into the door jamb and when you close the door the w/shield will hit this 5c piece and close the door so nothing can get under it, wind included.
There are expensive door seals so google 'Buy Raven Seals online', but a handyman or cartpenter may have to install these if you don't feel confident because you will have to take the door off to fit it.
There is another way but it's arduous and depending on the room under the house whether it's easy to crawl under is to take a handsaw, chisel with you and maybe a milk crate, where you sit this crate or anything else to fit snuggly under the joist, then cut with the saw in an upward direction of 15 ml on the joist, either side of the bearer, and then chisel it out, maybe another job for a handyman, I've done it before, plus I built a decking for my SIL that fitted exactly the same level as the house boards, because her daughter was in a wheelchair, but the bearers and joist shrunk only about 15 ml.
Have a look at these options and let me know. Geoff.
