FAQ: Faster ways to build?

One question I get fairly often is "is there any faster way to build the walls?" or "why not use formwork and pour the walls - wouldn't that be faster?".

Second question first: if you have access to formworks, GREAT! Just remember, concrete is basically a liquid when poured - your forms have to be SUPER strong to avoid a form blow out and spill. For a one-off job the cost and time of your formworks would probably be much greater then conventional stacked concrete blocks like I used.

Now for the first question: If I was doing it over I think I'd try surface bonded concrete. I'd heard of this technology before I started, but initially wrote it off as being a little too "fringe". Then I saw this:

Surface Bonding cement by Sakrete

If Sakrete is selling it, it must be at least acceptable, structurally speaking. Since then I've done more research. It appears that dry-stack, surface bonded CMU construction could be a great way to speed up the longest, hardest stage of construction. After we built the shelter we used cinder blocks to build some raised planters. We dry stacked roughly 200 blocks in just a leisurely hour or two. My entire shelter only used roughly 450 blocks. The planter is not subjected to a lot of forces, but it's held up well. I'm confident that with surface bonding and poured cores that you could get a wall up quicker and still have exceptional strength.

Drystack concrete planter

Here's a blog entry detailing how a family used drystack and surface bonding for a root cellar. It appears they managed to drystack at about the same rate we did and had a favorable experience with surface bonding. They do say, however, that they didn't fill ever core with concrete and rebar. I still advocate doing that.

Drystacking a root cellar

Drystacking may require a small change to the construction process, though. In my shelter, we laid up the walls, built our decking, and then poured the insides of the walls and the roof at the same time. We were able to do that because our walls were very sturdy. It may be that with drystacked wall, even surface bonded, that you'd have to divide your pour into two: one to pour up the cores of the wall, another to pour the roof. The good news is that if you are building a roughly 12x20 shelter, like I did, that pouring the walls and roof separately shouldn't cost extra in delivery fees, since both pours should be above a reasonable delivery minimum.