House porch appears to be on the move. House is built on clay. 200+ yr old oak within 20m of front door. Depth of porch foundations unknown (due to concrete drive I can't dig and look!)
A crack opens and closes in one side of internal wall, and concrete floor has cracked through effectively separating porch from house (connected by UPVC window and door frame + flat roof).
The crack has obviously been around a long time, and has been filled on numerous occasions. The crack in the wall never gets more than a few mil, butis enough to rip the wallpaper it was covered with by previous owners.
I want to get porch rebuilt anyway, but was wondering if rebuilding the porch and tying it into the house better (ie. top and bottom) would eliminate the movement. I would really like to avoid the words subsidence and underpinning if at all possible.
Rest of house is sound, cracking does show in mortar lines on external wall, but it just seems to be the bricks attached to the concrete floor of the porch.
Our survey did not pick up any problems when we bought.
Porch is approx 3m x 1.5m. Any ideas on a ball park rebuild estimate assuming new door, flat roof, brick walls? Just want a start point so when I get estimates I know they're not conning me!
What do you reckon?
Thanks in advance, apologies for longwinded post...