Last week, we set out to make some progress on stacking the urbanite foundation for our kitchen. There were a few things I learned from my own foundation, and a few things we wanted to do differently for this building. At first, we thought we’d want to dry stack the entire thing, but realized we would definitely benefit from some mortar, especially around the area where our giant posts will be sitting on the foundation.

I have not been super pleased with the clay/sand mortar I made for my own home, so I haven’t been pushing for a mud mortar. It wicks moisture big time and was a pretty big issue over winter and into the early spring — in those early days of spring, earthworms had managed to tunnel through the mortar into the house! (The mortar has since dried out. I think it was mostly wet from snow contact against the foundation over winter.)

Anyway, we decided we were willing to try a lime mortar, a 3:1 sand/lime mix to plug in areas around the foundation where posts will be set. I imagine we will end up mortaring most of the foundation, too. In this first course of urbanite, we made a chunky gravel/lime (3:1 gravel/lime mortar) mix to stuff cracks between pieces of concrete to fill the gaps.

We have been using some fairly giant pieces — our foundation is a whopping 24″ wide. So far, I’ve been pleased with how it’s progressed. Thankfully, we don’t have to completely worry about a level foundation. However, we are being careful to be level around those areas where the posts will sit, since we will have to create some kind of flat wooden sill for the posts to attach to.

I hope this lime mortar holds up a bit more sturdily than the mud mortar in my house. It will probably wick moisture as well (concrete wicks moisture, too, so it’s hard to avoid), but probably not as easily. The foundation will be three courses high, so we still have a ways to go!