Homes built on concrete blocks? (houses, construction, earthquakes)

[CrossEyed]

I had seen this at a distance while driving and shrugged it off, but was up close and personal today and it really confuses me.
We live in N Dakota, and I've never seen homes built like this, where it appears the footings are just the crumbled up lava with big rectangular concrete blocks on top of them with 4x4 lumber strapped to it.
Is this true? How can this be?
I saw this in Oceanview Ranches where we visited a friend of wifey's before walking down to the small beach at the bottom.

I've been involved with putting up quite a few barns and sheds, so I understand the single-wall construction I see on the older homes, but I just can't wrap my head around hat I am seeing for a foundation.
It looks like a big dozer just drives on the lava there to crush it, then they toss these big blocks on there, and start nailing away with the wood! Is that crushed lava really that stable? I suppose frost heave isn't an issue, but what about wind and earthquakes?

[hotzcatz]

If it's bluerock gravel under the footings, then it's stable. Bluerock is a dense type of cinder. If it's just crushed red or black cinder, then it may settle a little bit, but not all that much. If it does settle too much, you can jack up the house with a floor jack like you use for your car and put in a longer 4" x 4" post easy enough. If you're pouring a concrete slab, you're supposed to remove red or black cinder.

This is a huge improvement over the way things used to be. Way back when, it'd be a rock on the ground with a post on the rock. Around the thirties and forties, though, they started using concrete blocks instead of a rock. Up until the mid-80's, the standard practice was a big 'tofu' block (solid concrete) 16" x 16" x 8" with a smaller one of 8" x 8" x 6" on top of that with a metal termite pan (8" square metal sheet with slightly down turned edges) and then the 4" x 4" post. Nothing nailed together or cemented or glued, just one block with another on top. I'd always like at least nailing the termite pan to the bottom of the post, but not everyone did that.

The new standard post and pier footing now has the two blocks cast into one piece with the metal straps as part of the footing.

Nowadays for wind we have a 4' section of wall at the corners of buildings instead of just a post. That's new within the past twenty years or so.

If you're building a Hawaiian hale style of building, then the post was set on the lava rock ground with other big rocks piled around it to hold it in place. There are two different types of hale which can be build with a building permit and they have the post and rock foundation along with thatch or palm frond roofs.

[CrossEyed]

Thank you hotzcatz.
The blocks that their house was on was appeared to be one of those precast ones you mentioned. I did not see any termite pan though, just a 16x16x8 lower with an 8x8x8 upper with a metal strap molded into it that the 4x4 lumber was attached to.

I am certain the lava wasn't blue around the base, but it wasn't necessarily red either. It looked like all the other crushed stuff that was everywhere out there (wifey said it was aa???), even the road we walked to Pohue bay was the same crushed lava.

I suppose this just caught me off guarg as I've never even considered putting a building on a foundation like that. But then again, you guys on the islands seem to do things much different than we do back home.... be it better or not. Can't argue with that.

[hotzcatz]

Well, the climate here is just a tiny bit different than North Dakota. We like to put our houses up in the air so it gets wind blowing under the house to cool it. We're generally more about ventilation than trying to keep the heat in. Plus almost all construction materials are shipped in from 2,500 miles away, so less materials is better.

[terracore]

Unlike the Dakotas, we don't have frost heave, blocks on top are okay.

[leilaniguy]

Your're only worry will be if they wash away from under your house in a torrential rain.

[hotzcatz]

Yup, torrential rains near footings is another reason for wide roof overhangs. Our oldest house was built in 1911 and it only had a one foot over hang with no gutters. The water dripping off the roof eroded the soil from around the base of the house and about every third post was missing it's rock when we bought the house. Amazingly, it was still standing and we replaced all the old posts (some of them had been patched together instead of a solid post) with new posts that had the nailed on footings. Huge up grade from old patched together posts set on rocks.

[Jungjohann]

Originally Posted by terracore

Unlike the Dakotas, we don't have frost heave, blocks on top are okay.

Some areas are prone to lava heave...


Uuuurrrrrpppp, scuze me, hope this helps

[KaraBenNemsi]

Neighbor got issues with mongoose digging for insects through the gravel underneath the footing. Had to pour concrete over the gravel.

Few mongoose in the Dakotas, I reckon.