The Kind of Conversation We Have Often

Digging today was pretty minimal -- Tuesdays are always kind of busy and hard to schedule around -- but I did get the arbor taken down and the rose climbing over it both pruned and dug out. (And now I have another pile of rose prunings in the yard, yay for me.)

Arbor taken down

I also took out the tape measure and double-checked some of my guesstimates about where the corners will actually be, which was pretty useful.

When I got the climbing rose out, I uncovered the Stupid Pipe, which is to say the drain to curb that Contractor A lied to us about.

Pipe in the trench

Well, that will get cast into the footing. I could think of better things to have happen to it, but I can't be arsed to dig it all up and pull it out.

Tally for today:
Number of guys who suggested I hire them to do the digging: 3
Number of people who remarked on how much work this is: 5
Plumbing fixtures delivered: 1 (a toilet seat!)

Anyway, what with all my Tuesday things I got nothing else done. Then tonight, we were hanging out in the kitchen faffing about the concrete work and how we're going to build the forms. Noel wondered, as we talked about material costs, whether it would make financial sense to make one reusable mold and do the stem wall in small pieces, using sack concrete and taking nearly a month to be finished. After all, 3/4 of the concrete is actually in the footing, and it might not be so bad to work slowly across making the stem wall piece by piece. We'd have to buy the donkey tail rather than rent it for the day, of course, but we'd been talking about doing that anyway, and would the difference in the price of concrete delivered make up for the difference in the price of materials for forms?

So I whipped out the spreadsheet and did some quick calculations.

Reality checks are always so interesting. It turns out that the cost of concrete in sacks is the controlling factor for cost on this project ($715 without delivery charges, and that was definitely an underestimate because I didn't include the slop factor in there). The cost of pretty much everything else doesn't come close ($405 for all the formwork, or $59 to make one mold). Unless delivered concrete costs over $250 a yard (more than 3 times the national average), it's cheaper to just make all the formwork at once and do one pour of delivered concrete. And faster, which is definitely a consideration.

I sometimes feel like I've spent half of every day for the last week doing calculations and fiddling with spreadsheets, but it really does help to be able to get solid numbers when you're trying to make a decision.

posted by ayse on 02/09/11

3 Comments

Don't you have these over there?
http://maxit.materialbank.net/NiboWEB/maxit/getFile.do?cart=true&ticket=253019&cartUuid=2082755&name=Laastisakki_1000kg.jpg

That's a sack that contains 1 metric ton of ready concrete mix (or mortar like in the picture). Those large sacks are much cheaper than separate sacks, but of course are not man-portable. But basically it's lifted into place and then you just shovel the mix to a portable mixer, add water and there you have it.

When I was buying concrete for fence post bases one 1 ton sack was equal in price to 575kg of small 25kg sacks. (...but of course I managed to spoil the big one by not covering it properly and rainwater got in and...)

ouch. It's good that you're looking at cost and calculations now so you're not blindsided later on if you decide to do it.

Wow, Bror, no, we do not have huge containers of mix available like that. I could buy the various materials used to make concrete mix and mix up our own, but that's much more work than it's worth. And I suppose the risk of spoiling due to water is actually pretty high right now, it being the rainy season (good time to work concrete and cure concrete; bad time to store concrete).

Note: We're getting pummeled with spam comments, so I've turned off the ability to use any HTML or include any links for the time being. Email with any issues.

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