Concrete slab technology

[Ccat]

I am (still) thinking about building a new house (now that the lava flow is at bay).

I don’t want stairs (due to age) so I am thinking about a concrete floor/foundation.

(Given all the (little) earthquakes) What would be the be the most durable, affordable technology to build it with?

Rebar, welded wire mesh, post tensioning, special cement mix, etc.?

I want to be able to live on the concrete, ie it would the “flooring”.

Sincerely,

Ccat

[kalakoa]

You may also want to rethink a slab due to age. I developed aches/pains within a year of getting mine; would not pour another slab.

[dobanion]

Rebar, for sure. They have rust-proof fiberglass rebar available at Honsador now called "Gatorbar." If you want to go high tech on the cement mix, you can see if anybody offers metakaolin for the concrete, probably not. I shipped in a pallet of it from LA for my projects. Otherwise just get something with some fly ash and a 4000psi mix. Make sure the crew vibrates the pour.

Consider metal framing for the house.

[Ccat]

Metal, Definitely.   Wood is a disaster in Puna.

I am also thinking no conventional wood cabinets:  there are lots of other ways to do storage that would be serviceable and still look nice.

thanks,

Ccat

[dobanion]

Good point. "Traditional" north american construction has no place in Puna, or most of Hawaii, IMO.

Think steel frame, cement board, lots of stainless shelves and such, like a commericial kitchen.

Or just replace most of the house every 5 years, your call.

[Chas]

A couple of things I learned when we poured our slab:

 1. You need water. In our case we were able to use the neighbors hose/water. They need it for various things such as cleaning tools, washing things that aren't supposed to have concrete on them, etc. You will want it also, which brings me to my second point.

2. They will need a place to dump "waste" concrete. We had a pumper. They pump a small amount onto the ground before they actually start putting it into the slab/form area. If they are good, they will only have a little bit left in the hopper at the end of the pour, but they have to empty the hopper and clear the lines when they are done. It's a fair amount, picture two 55 gal drums worth or so from the pumper truck. I was able to get rid most of that by having them put it in a low area that I was going to cover later with gravel.

Whether you are pumping it or not, each concrete truck has to clear their truck of leftover concrete as well. This stuff isn't as bad since the driver will have a hose on his truck to spray it off. This dilutes it quite a bit but it doesn't hurt to spray more water on it to really thin it out if it's in a place you don't want chunks of busted up waste at the end.

Bottom line, you will need a place/plan to get rid of it. Be aware that this will happen, because unless you tell them up front, they'll put it where they think is a good place, which may or may not be where you think is a good place. One of the truck drivers cleaned his truck right next to my hand selected pile of lava rocks, splashing concrete onto them. I didn't blame him. Hey, they don't know. "It's just lava. They whole island is lava".

[Ccat]

A couple of things I learned when we poured our slab:

waste concrete

aha!   good point. 

I will plan ahead to make use of it.

thanks,

Ccat

[kalakoa]

If you dump the "waste" concrete onto some "waste" plywood, it can be finished into a slab, then (once it's firmed up a bit) cut into squares, as if making big concrete brownies. I ended up with several nice paving stones this way. Waste not, want not!

[dobanion]

Great point. I ended up having enough to leftover to make a parking spot.

[MarkP]

I think the benefits of having a slab to tie everything together are well worth it. I don't know what the options are for extra thick resilient flooring but I would look into it. I put in a bathroom in my parents house that was on a concrete slab and I first laid down a 1" layer of foam insulation, then a 3/4" layer of AdvanTech subfloor, then 1/4" luan over that, then click together vinyl. I am very pleased with the result as the foam and air trapped between layers seems to provide a decent cushion.