Brick porch underpinning

[shibbydibby]

Have a subsiding brick porch 1.5mts out by 3mts wide .. built 30yrs ago; one side is moving (more than the other side) away from the house. I suspect the builder either didnt give enough foundation or drainage (downpipe straight into the ground by the porch wall) .. or possibly the row of large leylandii conifers (30ft from house) have sucked water from the area having grown too big.
What ive done; As the ground around the house is always wet Ive diverted the water away from the house walls .. also have reduced the height of the trees by about a third to 25ft not wanting to cause heave.
Can anyone advise for such a small porch, assuming the footing was good enough at the time, can I dig along the 1.5mts wall to inspect the footing looking for a cavity (also assess soil moisture) .. and then if a cavity found fill with concrete and some steel rods ... or cut the trees by a further 50% for the gound to maybe bounce back?

many thanks for advice

 

[roberta1000]

If the surrounding ground is wet it doesn't sound too likely that the trees are draining it enough to cause subsidence. Most likely the builder didn't put in good enough foundations, quite common 30 years ago. They aren't tied to the house foundations and are subsiding a bit. I doubt if you'll get the porch back where it came from so likely the best bet is just to underpin as best you can, leave it a year or so for any final settling then fill the cracks.