concrete patio and potential room extension or expansion

Old 02-19-19, 04:19 PM
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concrete patio and potential room extension or expansion


I am in the SF Bay Area. There is a concrete patio in front of the entrance door.
What I want to do is to extend it to the end of side of the house and in the future I may extend the front wall of a bedroom over the patio for more space.

The house is one story with stucco siding.
The area is about 9.5 ft L x 4 ft W and the exiting patio is 7 in deep.
There is an outside hose bib there and two foundation vents.
Current foundation is a stem wall foundation.
The soil is clay and sandy in some area.

I plan to pour a monolithic slab foundation with 6 in thick for the slab portion. I will tie it to the existing patio and foundation.

My questions are:

1. Do I need sand on top of the gravel? Or compacted dirt is ok?

2. The two foundation vents will be partially covered. I don't know of a way to move the foundation vents. Any suggestions?

3A. To extend the hose bid and have the copper pipes buried in the concrete, do I need to wrap the pipe? What do I wrap the copper pipe with? PVC tape or PVC sleeve? Do you have a better solution/suggestion?
3B. The copper pipe is about 1.5" to 2" below the current patio level which will be the weak point in the concrete. Do I need to reroute it lower, to about 3 in, to be embedded into the concrete?

4. Any advice, comments, suggestions would be welcome.

Thank you for your help.
Old 02-24-19, 04:15 PM
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I would bet that the patio that have a sufficient foundation underneath it to allow a structure to be built on top of it. Unless you know exactly what's under it and there is documentation showing that I highly doubt any bldg. officials let you extend your home onto the top of it, especially in California.
Old 02-24-19, 07:55 PM
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I think what Msradell is trying to say is that the patio DOES NOT have sufficient foundation underneath it to build on. It needs a foundation that is under frost, and it needs to be insulated. You might as well demo that patio and start over, doing it all right from the start. Your first step is getting permits for the work and submitting a site plan.

And yes, you need to protect the copper from the concrete. I usually see the masons use foam pipe wrap.
Old 02-25-19, 05:23 AM
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Even here in NC without seismic concerns you can not add on/over existing without proving that the existing meets the current codes. Because the cost of investigation and Engineering is so expensive it's almost always cheaper to remove the old and start over fresh, up to code and so the inspectors can inspect.

Also, especially in a major city, you need to contact your Zoning Dept. for approval before beginning work on any expansion or addition. Getting the permitting worked out before hand is much cheaper than being caught and trying to come into compliance after the fact.

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