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-I've been thinking about building on my lot in the Hawaiian Beaches
area. Years ago I hand-cleared part, but had the future house pad area ripped and leveled with a D9 dozer.
Is the usual building code for a two-story house footing of 18" below undisturbed soil required for the lava rock in much of Puna? My design is for a large garage slab with 2nd floor above.Also, is it easier and/or cheaper to build the stem wall with concrete block, or formed for concrete pumping? ( Seems like the hard part would be staking the forms.)
Experience and knowledge much appreciated. Mahalo!
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I will try to answer your questions.
The reference to "undisturbed soils" is not a local term or usage. It is possible to form footings above grade on undisturbed pahoehoe but since you have had your lot ripped and leveled that is not an option.
You will be needing to import base course (gravel and fines) to further level and compact on your site. You may or may not need to compact the ripped site prior to this. Your issue will be settling of substrates after the slab is poured and building up.... you do not want settling. DO NOT base your slab with cinder. Waste of time, waste of money. Not legal. You would need to remove any cinder from the house pad which is not as easy as putting it in. Cinder is not competent material.
As for block wall vs.PIP for stem walls..... that is matter of preference and the skills and experience available.
I do like to remind people that the building codes are only the LOWEST standard of construction allowed by law. The codes are not instructions for how to build your home.
Assume the best and ask questions.
Punaweb moderator
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Rob, I bought a lot with a deck and footings. The deck may have to go, but i figured the footings for piers were super, entire underside stripped to rock(natural) on a slope.
They are standard pier blocks with tofu blocks . The main blocks are soundly cemented, level and plumb. Are you better to be on a shock absorbing base course platform or is the cemented down block ok. Thanks!
Gordon J Tilley
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Foundations, by definition, are the base for the building. Talking about "shock absorbing" aspects of base course is rationalization and wishful thinking. Your best bet is to be as firmly attached to as firm and competent a patch of planet Earth as you can find. You ideally want to be "at one" with an event. "At odds" with the motion of the earth can be very destructive. The planet will be, effectively, hammering the house. Which do you think will win?
Precast piers as foundations for houses are the structural equivilant of a mobile home. They're just square concrete tires.
Assume the best and ask questions.
Punaweb moderator
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Hi, new to the forum, looking for education. I read alot about "Ripping", Ah, Ah lava, Pahoe,hoe lava, D9 bulldozers etc. My question is how difficult is it to doze all of this lava rock? Mahalo!
