Hi All,
After a number of weeks of anonymous forum viewing I've decided to take the plunge and try and ask a question of my own.
I'm currently attempting to gain permission for a self build 35m squared timber frame garage on in my back garden. We currently have a area of parking space on gravel at the back of our house which I want to turn into a garage. The area at the moment is well compacted due to the amount of vehicle traffic.
I originally approached Wessex Water with a build over request with the aim being to build a reinforced 6" concrete raft on 4" of granular bedding over a 225mm storm drain that is approx 1.6m below ground level. Wessex Water approved the request and design and told us basically to crack on and let them know when we're finished. They CCTV'd the pipe and found it in pretty good condition, there was only one circumferential crack in a single section approx 10mm from the end ('m not even actually sure that within my boundary.
Unfortunately, a bit further on my structural engineer now has expressed concerns that the sewer may collapse during compaction of the bedding with a wacker plate. The load of the building isn't a problem as it's distributed over such a large area and it's relatively light weight. The subgrade below is stiff clay if anyone's interested.
I suppose gucci option would be to dig down to the sewer and encase in shingle and place a pre-stressed lintel above thus removing any possibility of fracture during build but is this overkill?
I'm not particularly concerned about the building load later on. The raft will effectively distribute the load over a large area and the ground has been subject to traffic loads for at least 10 years with vehicles driving over it with no issue.
Can anyone offer any advice on the best solution? I need to talk to my BCO to get their opinion but additional input would be welcome.
After a number of weeks of anonymous forum viewing I've decided to take the plunge and try and ask a question of my own.
I'm currently attempting to gain permission for a self build 35m squared timber frame garage on in my back garden. We currently have a area of parking space on gravel at the back of our house which I want to turn into a garage. The area at the moment is well compacted due to the amount of vehicle traffic.
I originally approached Wessex Water with a build over request with the aim being to build a reinforced 6" concrete raft on 4" of granular bedding over a 225mm storm drain that is approx 1.6m below ground level. Wessex Water approved the request and design and told us basically to crack on and let them know when we're finished. They CCTV'd the pipe and found it in pretty good condition, there was only one circumferential crack in a single section approx 10mm from the end ('m not even actually sure that within my boundary.
Unfortunately, a bit further on my structural engineer now has expressed concerns that the sewer may collapse during compaction of the bedding with a wacker plate. The load of the building isn't a problem as it's distributed over such a large area and it's relatively light weight. The subgrade below is stiff clay if anyone's interested.
I suppose gucci option would be to dig down to the sewer and encase in shingle and place a pre-stressed lintel above thus removing any possibility of fracture during build but is this overkill?
I'm not particularly concerned about the building load later on. The raft will effectively distribute the load over a large area and the ground has been subject to traffic loads for at least 10 years with vehicles driving over it with no issue.
Can anyone offer any advice on the best solution? I need to talk to my BCO to get their opinion but additional input would be welcome.
