1st. Extracting the house. Better use pen tool, not MW combined with colour range, like myself - messy!!
2nd. I wanted to make a lake house so i needed a grid for the accurate render of the pillons - later will serve for reflection.
3rd. The pilons are made from pieces of wood from the house with liquify & burn for the round shape. starting the reflection using another grid as u can see in step
4. Reflection under object is more difficult than those with the object near the water ( not in it. I had to create the bottom of the house using other planks from the source & the grid.

1st. part of step 2: making the reflection of the house by warping walls - easier to say than done ( at least 4 me).
2. With all set, i was preparing to work on the river banks & background.
3. By pure mistake i saw the effect of the reflection on earth after turning off the river layer - I said WOW, and started wasting another day on this new lead.
4. This is after finishing the pillons and the background while i was adjusting the shadow. At this point i start doubting this was a good lead.. i mean i have to double work now: shadows & reflections!!!!
If anyone read so far, he gets 5 bucks from me.

This last step is after i got tired working 3 hours on decks & piers to fit in the image and have some ruin-ish aspect. I abbandoned that idea cause i started hearing voices. I took me a while to find a nice boat and blend it in the landscape and patched my work with that ladder.
I calculated the shadows with a diff. layer as you can see- might not be too accurate, cause i'm not Google SketchUp. If you have ( time, cause you're not reading a random SBS) 3Ds in your manipulation and need to be sure of shadows, recreate it in Sketch- it's easy to fix the light you need there.
This is it, any questions you have, let me know, it s 4 am here - me out.