Are you sure there is no wall insulation? I can't imagine a recently redone lathe and plaster wall without insulation (and the necessary warm-side vapor barrier). Usually the dilemma is a house like mine with no wall insulation and original plaster and therefore no way to insulate without damage to the historic materials. Don't get confused between the vapor barriers installed in the wall assemblies just underneath the interior wall finish, i.e. on the warm side of the insulation and the moisture and air infiltration barriers installed under the sheathing or other exterior cladding. The former is to block tramission of interior moisture into the insulation material where in cold climates it can condense and get trapped causing mold problems. The two later products are intended block exterior moisture, primarily rain, from being driven from the outside into the wall assembly. The standard order of march in weatherizing an old house: insulate the attic cavities, first; then do a heroic job with the caulk gun to eliminate small air leaks, inside and out and install or replace weatherstripping around openings of doors and windows; then look at wall insulation. Note that under floor insulation is not high on this list even though it is an intuitive thing. Floor insulation projects are usually aimed at stopping air infiltration but most insulation materials aren't designed to combat infiltration, per se. However, tightening up other, higher, parts of the house will prevent them from drawing cold air up through the floor in the first place. This overall plan of attack is based on first doing the things with the most efficient payback in energy savings for the dollars invested. And sexy, or not, attic insulation and caulking are the top two. For under your structure, you may need a vapor barrier laid on the dirt to stop moisture vapor from rising from the soil into your living space and the framing of the structure, and possibly ventilation of the crawl space (this is the controversial part and I think depends,greatly, on local conditions especially your outdoor drainage situation.) BTW, I would carefully assess the choice between wood siding and Hardie-plank type products. They are not equivalent in how they look and I think the HP makes an old building look odd. Unless you siding is totally rotted, you can probably rehab most of it, then buy only a small amount to finish the job. There is a series of National Park Service publications regarding the care of old buildings. One title is devoted to weatherizing old structures. I've attached a link below, scroll down the list of titles until you find the ones that interest you. HTH, Molly~ Here is a link that might be useful: National Park Service Preservation Brief Series - Wide range of old house topics

Since you have already removed the plaster and lathe, the walls will be your number one priority. First, repair and repoint the masonry wherever needed. Then apply a liquid vapour barrier to the inside of the masonry. Next, recommended insulation includes closed cell polyurethane spray (my favourite), expanded polystyrene board (XPS), or extruded polystyrene (EPS) depending on your target R factor, the space you have to work with or other variables. Pay special attention to sealing the old window frames to the new insulation, even building new internal frames if necessary. Your goal is to make the insulation as tight and free from air movement as possible. Read the up-to-date digest in the link below from one of the leading experts in the field for details. Once you're done, get to work on the other areas of your home. Here is a link that might be useful: . Building Science Digest 114

Those aren't studs; they are furring strips over masonry. If this is a solid brick home, there won't be any studs on the exterior walls...or not any that are original to the house. Studs in partitions, yes. If you want the wiring inside the walls, then you are going to have to frame out the walls...like what is often done when finishing a basement. This will give you the opportunity to add insulation as well, But it will cost you floor space and the windows will either need to be replaced or jamb extensions added. Or, you could run wiring in conduit, cutting away sections of the furring, providing that the strips are thick enough for the EMT. If not, then you will need to add strips on top of the existing ones to gain enough depth. Or paint the surface wiring the same color as the baseboards. Plaster is a much nicer wall finish than drywall, IMO, so I would try to preserve as much of it as possible. Looks to be in great condition for a 100+ YO home.

Spray foam will be a mess if you ever need to work around that area again. Not a fan of PEX in walls as its easy to puncture and if sprayfoamed would be difficult to repair. either have a plumber come and move pipes out from wall and put high density foam board, fiberglass batts or plywood and fill with cellulose. If this is a basement on an exterior wall with no water tight barrier than its really down to foam board or spray foam.