We are finally plastering the interior of our 1927 craftsman home restoration. Project pasge
Many of the walls are severely cracked from a massive earthquake in Richmond that brought down a few buildings including the historic stone church a block away. There has also been delaminations from 40 years of leaky roof(no exaggeration).
We air sealed(Pro Clima DB+) and insulated the exterior walls(Roxul R-23 batts), so they have been covered in drywall. The DB+ paper sticks out on the edges and is hot-mudded(gypsum) to the plaster walls with some fiber tape to prevent cracking.
We use our own custom blend of lime, gypsum, sand and manure to repair the cracks in the plaster and even to plaster right onto the wooden lath where the plaster is missing.
The lime putty was mixed 2 weeks ago from bags of hydrated type s lime.
Basic recipe; 7.5 gal lime putty, 7.5 gal all purpose joint compound (I like National Gypsum for all my gypsum needs) 2 big shovels full sharp quartz sand and 1 big shovel full horse manure or if you would like to do the work of the horse, you can shred the straw yourself.
Once the plaster has been mixed well, apply to a well wetted wall ensuring proper adhesion and key by splatting each bit of plaster onto the wall. Then after a dozen or so plats, trowel smooth. Let dry just a bit and trowel off, holding the trowel at a 45 angle to the wall, which will raise the sand so the next coat can bond well.
If we cut open a wall like in the first photo where we cut open the wall for a walk-in shower, we save the lath and re-install the wooden lath on the new section. I don't like to use drywall for this because of differences in expansion/contraction causes cracking.
This first coat is thin, just enough to cover the lath well. When this has dried for a few days, then we will apply another coat of the same mix, but sometimes even more sand like 1 lime to 3 sand. This coat levels everything up.
could you please elaborate on how you insulated the exterior walls? is it correct to understand that you added a layer each of (1) pro-clima (2) rpxul, then (3) drywall over the existing plaster wall? if so, how much thickness did this add to the wall? also, could you also explain what you mean by hot-mudded?
I think having land and not ruining it is the most beautiful art that anybody could ever want to own. - warhol
The exterior wall assemblies are 1- 1 1/2" lime plaster, 3 1/2" dense packed cellulose, 1" lime plaster, 5 1/2" Roxul R-23 batts, DB+, 1/2" drywall, topped with 1/2" lime plaster. This adds 6 1/2" to the wall thickness, so the doors need to be remounted in new frames and the windows just get more trims.
I mean setting gypsum, but we have started to just use our taping mix for this as well.
So, sometimes you've got a complete delamination and you must rebuild the lime plaster from the lath up. The well haired base mix is pressed firmly, but gently into the lath in one clean motion from the hawk to the wall and up. This ensures proper key while not spreading the mud too thin.
Once the render is set up but still wet, scour the surface lightly with a wooden float. Then scratch diagonally across the surface with a pointed lath board to provide key.