Looks like sanded plaster worked smooth. I know that is no help...
Casey

I'll add my two cents, but keep in mind it's not worth even that much...
:-)
To me, plaster walls don't produce a "hollow sound", that's what drywall is for... Drywall = hollow sounding, sound amplifying (not literally)... Lathe/plaster = solid sounding, dense, sound-muffling.

I assume you are, at least sometimes, nailing/drilling into studs behind the layer of plaster? Plaster CAN be hard, I think, & I suspect there were different "recipes" used - some more dense than others. (This is truly an assumption). But I KNOW that old houses (mine) have old pine studs that can make a good Bosch drill squeal in a truly ugly manner, bend any nail you try to get into it, & hold our houses up for a hundred years or more.
Is the plaster the issue, or what's behind it?
I'd love to see more pics - of the interior, where there are cracks & where there aren't. And exterior, I'm a nosy one - & I always want to see! :-)

Thank you sombreuil and ks_toolgirl! After reading your posts, I started doing some digging.

In the bathroom, one of the previous owners put wood paneling (ewww!) on the walls and installed some really stupid built-in soap dishes which required cutting holes in the walls. I managed to remove one of them and lo and behold - it's the sturdiest lathe and plaster I've ever seen! The stuff looks like inch-thick cement and has horsehair sticking out of the cut edges. When we were looking to buy this house, all of the inspectors told us that, despite its age and quirks, the house is built like a fortress. They weren't kidding!

plaster basically is basically vertical cement. to avoid cracking, predrill all your nail holes with a high-quality drill bit. if there is a ton of cracking that suggests a particularly hard plaster. nothing to worry about. i like the look of the cracks, but you can obviously repair them with relative ease if you feel like it.

are your exterior walls brick? if so the exterior wall plaster is likely directly on the brick, meaning no air cavity, so it would feel really solid.

I've also heard that masking/painters tape, applied in an "X" over the predrill spot, helps prevent cracking. I've never tried it, though... Perhaps someone else has?
Lol - my upstairs plaster walls are "hairy", too.

If you're concerned that the cracks indicate current or ongoing structural issues do this:

Take a soft pencil and using a ruler draw some 3-4" long lines across the crack at right angles to it. Write the date right on the plaster. If the crack is active the line will show it by moving to make the lines offset. Forget about the marks for awhile. Check on them in 6 months or a year. I do that every time my eye "sees" a "new" crack and years and even decades later when there is no movement I'll see my old mark and be reassured.

Not even a direct it by a tornado that drove a 36" diameter tree straight down through our roof made any of the old cracks change. Of course it made a few (LOL) new ones and I lost track of some of the old ones in the ceiling in the kitchen when it fell in due to the rain that flooded the attic when the tree pierced the roof. But for that, I had insurance!

BTW, as you've discovered all kinds of utility and fixture points and old repairs offer very useful peeks into hidden spaces without making any further damage.

Sturdy old horsehair plaster is the nuts: very quiet inside and mutes outdoor noise. It also substantially moderates temperature swings indoors staying cool into the early summer and retaining warmth through midfall. People are often (ill)advised to tear out plaster but it is a vastly superior wall surface and often prohibitively expensive to replace in kind, so people opt for the second-rate choice of sheetrock. Guard and treasure your plaster, for they certainly don't make it very often like they used to do.

HTH

L.

Liriodendron - What a terrific idea! There are a few little cracks that look 'newer' than the rest, and I'll definitely mark them.

And yes - I'm falling in love with the horsehair plaster! In our old house - which had very thin walls - I'd lie awake at night and listen to our pet rabbits rattle their toys a whole floor away. Now I can't even hear the aquariums right outside our door. Wonderful!

If we can just clean up what previous owners have done, I'll be happy. An attic finished in the 90s has all of the electrical outlets installed upside down. A door in the basement office won't open all the way because it hits a ventilation duct. There is old paint splattered on all of the gorgeous wood trim throughout the house. Sheer laziness! The list goes on and on. But we will put it all right in time. I'm going to strip four layers of paint and restore the wood trim in the two bedrooms this week.

I'm all for the plaster too. I have a 1900 brick & plaster semi in Lancaster County, PA and love it for all those reasons.