I need to lay a length of pipe(s) (Approx 6m) under my patio to take rainwater away collected from my guttering. Unfortunatly the outlet which the water will flow into is only about 12 inches below the patio so the pipes will have to be laid quite shallow. Any tips on how this might best be acheived, as obviously I don't want the pipes to break or for ther patio (once relaid) to subside.. I am currently think of laying the pipes (underground drainage pipes) in sand, overfilling with a level of shingle and then completing with soil.
Will standard waste pipes be good enought or do I need somthing much stronger, if so what?
Not quite sure what shingle is but at 12 inches your normal poly pipe will withstand quite a bit of pressure, unless your driving a vehicle on the patio you will be fine. If you intend to use the black pipe with the holes in it over time you may have sinkage.
If you live in a northern climate. I would recommend using a fairly larger pipe then down spout due to the 12 inch below grade being within the frost line. A larger pipe aprox 4" for standard down spout to feed will allow for some water to freeze on the bottom of pipe and still allow plenty water flow above in warm up periods before ground thaws. Be sure to keep a pitch to the pipe not to puddle inside. I would recommend a PVC pipe and as previous reply stated unless you are driving a car over your patio shouldn't be a problem. (with PVC 12" below grade you could probably even safely drive a car over it, I wouldn't store one on it though)