Slab prep and pour

The cold and rainy spring is finally over, and with it the last thing which was preventing the building of the shed to get properly under way. I’m happy to report that I now have a lovely 20’x44’ slab where the boat used to be, and will soon be moving the boat onto it and building a shed around it.

The preparation of the space began quite some time ago, and was seriously hampered by weather and the folks who were hired to do the work having more customers than just me to fit into the few weather windows that did exist. They did a great job in the end, though – Eugene Lenihan having prepared the ground by scraping away the very thin layer of topsoil and roots and replacing it with sand and then gravel to build up a level pad to pour the slab onto; and Jim Rafuse having set up the forms and metalwork and actually poured the slab.

This way of getting a foundation for the shed means that this shed already costs more than the old one, which seems extreme, but… The last one would have blown away in a storm without the boat inside, since it wasn’t tied to the ground except by gravity and the boat’s weight. It also would flood in rainstorms and was impossible to really keep clean. This shed will be possible to clean, will stay dry, will be possible to seal against local animals (you may recall that I had a mother racoon give birth to two babies inside the boat two years ago?), and will give a fantastic level and smooth working surface. It also means the she is permanent, and is worth spending this kind of money on.

Enough philosophizing – on to the photos of what’s happened since the last instalment.

The slab prep did take awhile, and there was some question as to whether or not it needed to be an “engineered” slab or not. The difference is that the engineered slab has a deeper footing and more rebar, and is usually required for slabs of over 600 sq. ft. (which this one is, at 880 sq. ft.). Given how light the building is that is being built on this slab, engineering it seemed like overkill. On the other hand, the slab may well outlast the building, in which case who knows what will go on it afterward. A standard two-storey building does require an engineered slab, so that’s what we put down in the end.

Here’s the prepared ground along with the forms and metalwork:
Slab preparations

Detail of the rebar in the footings
Slab preparations - rebar and wire mesh

Ready for the pour
Slab preparations - ready for the pour

As it turns out I was away for the actual pour – work took me to Dallas for two weeks and I missed it. Looking at the end result, it’s quite clear that it all went well – the slab looks great, level, smooth, solid. And so far no cracks. I gather from what I’ve read that a slab with no cracks at all, ever, is a very rare thing, so I’m not hoping for that, but I am hoping for as few as possible. Being away for the pour is a good thing in one way, since the longer that concrete has to cure the stronger it gets, and it was poured a week and a half ago already, meaning that when I do put the boat on it it will have gotten much closer to full strength (which I gather is only achieved after months of curing, although 80% is achieved after a week or so).

Here’s the slab now, ready for me to start working on the shed:


The only detail on the slab other than the j-bolts around the edge to attach the structure to is the wiring chase that was poured in. I’ll have to make sure I’ve got lots of steel wool in there as well if I don’t want visitors crawling in through the pipe!
Wiring chase


The door end has fewer bolts.

So my next step is to build the little knee wall. Since the last entry I’ve changed my mind yet again on how to build the structure, although not by much. I will build a short (~1.5’ high) knee wall out of 2×6 which will be through-bolted to the slab. Basically it’ll be a standard stick-built wall, but short, and with a vertical 2×4 on top to accept the bottoms of the bows. I’ll drill and through-bolt the whole thing to the j-bolts, using threaded rod and a threaded connector, then a nut and washer on top. This will give the the ability to have a 1-1/2’ high knee wall which is essentially as stable as the ground, which was a problem with the last shed.

I’ll hopefully post details and pictures on it before too long!