Restoration & Refurbishment

Refurbishing 40 year old porch not sure what it's been built on

Anonymous user 17/03/2024 - 2.31 PM

I have a 40 year old brick porch. Roughly 700mm deep x 2220mm in length. Normal lean type style It has a double brick pier on the front corner with a single brick wall leading back to the house. Wood frame window built on a single brick half wall and wood door attached.Tiled roof. I'm having UPVC window and door to replace old wood ones and a new roof constructed to accommodate height of new door and window. There has been some slight movement in the join between the house and the porch less between hairline to 1.5mm. This has happened twice in 40 years. I think it might be built off a concrete pad 4 or 6 inches in depth.There maybe more under the pier. Surveyor has suggest the use of Helifix bars to be used across this crack to add robustness to original ties, plus tying in of walls to new roof. Both builder and surveyor seem unconcerned about what's underneath saying it has passed the test of time. I can't get passed the fact that I don't know what it's built on and concerned that the new window and door will be adding weight to the construction. Am I right to be worried or should I just let the work go ahead? Built on London clay.