Waterlogged garden and house - Advice on a land drainage plan

[landdrainsteve]

After reading much of the forum and the expert advice on land drainage I would like some feedback to my land drainage situation. The house sits on a high water table and the rainwater downpipes go straight into the ground, with no soakaways away from the house. Thus when it rains there is plenty of surface water around the house which finds its way under the floorboards. I am assuming that the downpipes are the main root of the problem. The garden slopes down from the back to the ditch at the front.
I plan to install solid underground 110mm pipes across the back and front of the house joining at the side to take the roof water off to the ditch, hopefully between 300 – 450 mm below ground with a 1:100 rise. I plan to surround the pipe with at least 75mm of 20mm shingle to help excess garden water to follow the route of the pipe to the ditch. A land drainage pipe will also join the solid pipe taking water from the back of the garden. I also intend to put further connection points in the solid pipe just in case I need to install land drainage pipes across the front and back if the shingle around the solid pipe is not sufficient to take any excess.
Here are my questions. Will the underground pipe take the weight of a car parked on top? Will a 110mm pipe be sufficient to catch a large roof space from an approx 22m x 11m house? Will the shingle provide a path of least resistance for the majority of any excess? I decided on solid pipe because of all the debris that comes off the roof and felt a land drainage pipe would silt up quicker, is this a good idea?
And finally does anybody have any others ideas to solve my problem?
Many thanks,
Steve

[seanandruby]

You could T filter drain into pipes that run to your ditch. dig trenchs, lay enough terran to do sides bottom and overlap at the top. Place shingle then terran wrapped filter drain cover in shingle then overlap excess terran.

[surreyhillslandscapes.com]

I would make sure you have some kind of wire gauze at the top of your downpipes to prevent moss and leaves getting into your pipework, it may also be worth installing a gully top with a pea trap at the bottom, if not at the very least you should make sure you have rodding access.

[Tony McC]

Will the underground pipe take the weight of a car parked on top?

Yes, as long as it has sufficient cover and is properly installed. uPVC pipes are prone to deformation, which is why the usual recommendation for pipework beneath trafficked pavements is for clay pipes, or for the uPVC pipes to be encased in concrete with flexible joints at regular intervals.

Will a 110mm pipe be sufficient to catch a large roof space from an approx 22m x 11m house?

No problem at all. You'd be surprised at the flow capacity of a 100/1100mm dia pipe.

Will the shingle provide a path of least resistance for the majority of any excess?

Yes, assuming the ground conditions are suitable

I decided on solid pipe because of all the debris that comes off the roof and felt a land drainage pipe would silt up quicker, is this a good idea?

Yes, but you could use a silt trap if necessary

And finally does anybody have any others ideas to solve my problem?

The best advice comes from an onsite evaluation by a drainage professional. There may be factors which you, as an amateur/DIYer, will not recognise. We can only base our suggestions on the information provided.