Hi,
I am building a double garage next to my 2 year old (new build house). The build is happening within 5 meters of an old english Oak tree.
Originally we didn't involve an engineer to design the foundations (silly I know) and when the build started, the council inspector advised that our proposed foundation (raft) is not suitable for the environment (next to a tree).
We were told that the usual approach in this situation would be to go for a pile based foundation (9 piles 4-6 meters deep). We've now involved an engineer who's advised that piled foundation won't be necessary, and we'd be fine with an enhanced raft foundation which includes additional depth on the corners, polystyrene sheeting, clay-board and double or triple re-enforced layer of mesh. His logic is: because the structure is quite light, even if there is movement and/or heave the entire structure will move on the raft without breaking up or cracking (subsidence).
Given this will be a formal design from an engineer I am tempted to accept it and move forward with a slightly revised version of foundations at a little extra cost.
HOWEVER I am worried that given the advice from the council was to go for piling, I may experience subsidence 10 or 20 years down the line which will de-value my property and make it very difficult to sell in the future. Obvious problems with Piling - hugely expensive - got 2 quotes - at least 5k excluding the top of the foundations, and would delay my project by an additional 3 weeks.
I wanted to see if people had experience of this sort of thing and what advise you may have for someone in my situation.
I live in the south east (berkshire) and building on clay (not sure what the density is).
Thanks.
I am building a double garage next to my 2 year old (new build house). The build is happening within 5 meters of an old english Oak tree.
Originally we didn't involve an engineer to design the foundations (silly I know) and when the build started, the council inspector advised that our proposed foundation (raft) is not suitable for the environment (next to a tree).
We were told that the usual approach in this situation would be to go for a pile based foundation (9 piles 4-6 meters deep). We've now involved an engineer who's advised that piled foundation won't be necessary, and we'd be fine with an enhanced raft foundation which includes additional depth on the corners, polystyrene sheeting, clay-board and double or triple re-enforced layer of mesh. His logic is: because the structure is quite light, even if there is movement and/or heave the entire structure will move on the raft without breaking up or cracking (subsidence).
Given this will be a formal design from an engineer I am tempted to accept it and move forward with a slightly revised version of foundations at a little extra cost.
HOWEVER I am worried that given the advice from the council was to go for piling, I may experience subsidence 10 or 20 years down the line which will de-value my property and make it very difficult to sell in the future. Obvious problems with Piling - hugely expensive - got 2 quotes - at least 5k excluding the top of the foundations, and would delay my project by an additional 3 weeks.
I wanted to see if people had experience of this sort of thing and what advise you may have for someone in my situation.
I live in the south east (berkshire) and building on clay (not sure what the density is).
Thanks.
