Building on bedrock without blasting
Arion
| Posted in Green Building Techniques on
Hello,
I hope you can help me with some options for building on bedrock without blasting.
In short, I am looking at a lot in the Gulf Island, Canada that has a lock ledge with a spectacular water view beyond. People are walking away from purchasing this lot because of the blasting costs. I don’t want to blast for the purpose of putting in a foundation. Instead, I would like to build up in order to maintain the integrity of the natural landscape. What are my options/costs attached to this technique? Am I going to run into a problem finding a contractor who is familiar with this technique?
Warm regards,
Mazzy
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Replies
Mazzy,
As long as the rock is stable and suitable to build on (which is the case on most of the Gulf Islands) you have two options: You can build on piers, either concrete or wood, or you can build your foundation walls (without footings) directly on the rock. Neither of these are complicated or expensive.
Because both of these options are commonly done here, and builders are familiar with them, I wonder if something else is in play that is affecting why the lot is seen as unbuildable? Is access, servicing or a suitable spot for septic a problem?
Thanks, Malcolm,
Much appreciated.
Those sound like to viable options that I will explore in more detail. I am just not a big fan of blasting and destroying the natural topography.
I have just sent a builder on the Island a query regarding building on the lot, i.e., the upside and the downside. I will wait to hear back from him.
To answer your questions, the driveway is pushed in but overgrown; it could easily be cleaned up. There is a well on the property that is capped. And signs of an electrical pole somewhere on the lot with electricity attached, thus, I don't think servicing the lot is an issue. This said, there is an older septic field on the property that would probably have to be redone in light of the new regulations.
Warm regards,
Mazzy
Mazzy,
Get a good architect who can work with the topography and use it as a feature to design around. Challenging sites often provoke the best design responses.
A pure guess, but I expect that rebar drilled into the rock would be beneficial.
The Gulf islands are all high-seismic zones. The anchorage will have to be specified by an engineer. We used to mortar re-bar into rock, but recently the jobs I've been on have had threaded bar epoxied in place.
Thanks, Malcolm and Jon,
Lots to think about here as I move forward.
Warm regards,
Mazzy
Which island is it? I live in the area on an island where blasting is common on a lot of new lots. I would discuss the lot and pictures with a blasting company to see how much or how little would be needed, it may be less than you think. I'd also consider how water would reach the house-to get the pipe to the required depth to prevent freezing could require rock to blasted/chipped away. A blasting crew costs around $2000 per day here.