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Running cable under patio stones that end against a concrete foundation wall

Kevin_Edmund's picture


We need to pass a single cable accross the width under our stone patio that butts right up to our house (concrete foundation). The propsoed solution is to simply lift the stones up and out of the way and then make a trench trhough the levelling stone and base as needed. Then refill the trench and relay the stones. The problem is that, by next summer, the stones will shift even if you tamp the stone bed/levelling sand/stones.

I've seen various solutions going under the patio stones without lifting them up, including: hydraulic jet (aka pressure washer nozzle), ramming a conduit under and using an electrician's flxible auger (I've seen these options discussed on this website too).The hydraulic jet will likely cause its own problems when the water gets to the concrete foundation wall where it has no where good to go and likley disturb the soil as well. The other two options seem good to me.

The person proposing the trench solution says that you will not be able to know where the tip will exit against the concrete foundation wall. However, all of the youtube videos I've seen show very good accuracy with either ramming a metal conduit (by hand) or drilling a long flexible auger bit with a drill. Is this just video magic?

With the last two options, we can lift perhaps only one stone next to the house and dig down to meet the conduit pipe or the auger. One stone against the house lifted out of the way is not likely to be as bad as one or two rows across the entire width!

Are all the videos i've seen just setups or are these techniques fairly accurate? I could even see using a metal detector to confirm where the pipe/auger ends up!

Look forward to your comments!

Simply ramming or using a (post #216183, reply #2 of 3)

Simply ramming or using a hydraulic auger will disturb the base worse than digging up.

I can't quite visualize the flexible auger solution.

Any of your boring solutions will have trouble if there is any stone in the base.

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Conduit (post #216183, reply #3 of 3)

List the stones, dig out enough to run a conduit and a spare. PVC onduit is cheap. 

Tamp the sand back down and make a screed that fits between the stones that weren't diturbed. Put ears on the screed to ride on the undisturbed soil with the bottom of the screed set to the proper depth for the patio stones to lay back down on.