Lime Plaster Phase I

The first priority for plastering was getting the interior bathroom walls, of both the house and casita, plastered.  The reason they started in these specific areas was that the walls needed to be covered in the lime plaster so they could build a furred out wall in front of the lime plaster.  Why would we need a furred wall in front of the straw bale wall you ask?  Well, we needed some place to run the water lines to the sinks and it is a lot easier to run them through a furred/framed wall versus a straw bale wall. And we need the straw bales covered in lime plaster to not only protect the bales and provide structural integrity to the house, but also to create an air tight seal to go along with the Passive House design.

The first step in the process was to cover the earthen plaster walls with a metal lath, which looks very similar to chicken wire.  If the plaster is being applied over any substance besides earthen plaster, such as wood, a layer of felt paper has to be installed under the metal lath.  This is due to the fact that the lime plaster will draw the moisture out of the wood and could lead to cracking of the plaster.  Once all the prep was done it was time to start plastering.  It takes a couple of coats of plaster to get it to the desired thickness of about 1" and the plaster has to cure for at least 10 days between coats.  Thus this is not a quick process.

First layer of plaster on the wall

You can see the multiple layers of plaster

The west wall of the main bath in the house is plastered!

The casita bathroom's east wall plastering is complete

Once the plastering was complete the furr out wall was built and the plumbing for the bathroom vanity was roughed in.

The casita's furr out wall is framed

Plumbing for the vanity sinks in the houses is roughed in

While the plaster team was on-site, they also weathered-in the garage.  To do this they wrapped the building in felt paper and then covered that with the same metal lath they used in the interior of the house and casita.  This will protect the plywood sheeting from UV and water damage during the summer while we wait for the temperatures to drop back below 86º F.  86º F is the magic number at which the lime plaster can be applied according to the manufacturer.  Fingers crossed this happens in early October.

The west side of the garage wall felt papered and lathed

Close up of the lathe over the felt paper

To provide some reinforcement on the corners a layer of "blood lath" was installed under the standard lath.  They call it "blood lath" because once it is cut to size the edges are very sharp and irregular and if you are not wearing gloves, it can really cut up your hands.

"Blood lath" on the corners

It will be a while before the plaster team is back on site.  In addition to having to wait for the temperature to drop, the ceiling planks, additional insulation in the interior walls, and drywall needs to be installed.  Much more fun to follow!