Home & Garden Columns

Living With Old Plaster Walls

Friday November 09, 2007

I tend to stare at the ceiling a lot. I think it’s only to be expected. If you sleep on your back or lie on the couch reading Jane Austin (as we all must), you’re bound to spend a certain amount of time staring off into space and guess what’s there … between you and space but your ceiling. There it hangs (Yes, that’s what it’s doing, hanging.) between the walls, with all those cracks and stains and Grateful Dead posters and you think, “Maybe I should do something about this mess but what can I do? It’s a ceiling, not a casserole. I don’t know where to begin!” 

Many of us live in handsome old casas lined with walls and ceilings of lime plaster, a product made of limestone and transformed through baking and hydrating processes until we have the powder that makes useable plaster.  

In the houses of a hundred years ago and all the way up to about WWII, plaster was installed over wooden lath. This is essentially how this worked. Once a house was framed, a lather would install thin strips of redwood, lining the rooms of the house with these thin, furry and somewhat wiggly sticks. They varied in length, since there was no four- or eight-foot module and would run as long as the wall or ceiling allowed, getting spiked into place with lots of tiny “blued” lathing nails (bluing is a low-cost rust prevention).  

The lath was spaced about three-eigths of an inch, and when plaster was smeared across the lath surface, it would get smooshed (like my technical lingo?) though the spaces and dry into a shape that could no longer fit back out. This held the dry plaster in place. The plaster also dried onto the furry surface of the lath, further grasping the plaster. 

What I find fun about this technique is that it smacks profoundly of wattle and daub, a technique that is at least 10,000 years old, using wooden sticks similar to wooden lath with clay or dung smeared across the surface and finished into a hard surface. This was how walls in homes were commonly surfaced in many early European for eons. There truly IS nothing new under the sun. 

Anyway, I digress and then digress some more. 

Plaster was applied to the wooden lath in two or three coats of increasing hardness and decreasing viscosity so that the final layer could be quite smoothly applied and dry to a very hard surface. This actually becomes something of a problem for modern homeowners who want to stick Grateful Dead posters on their ceilings. They end up with cracks and also have a helluva time driving those thumb tacks in far enough. The wiser person puts up their poster using a tiny drill and a slightly fatter nail. Drill bits can be found in very fine sizes. 

In the era of WWII, wooden lath was replaced with gypsum lathing board (aka button board). This was the first use of the new gypsum plaster and predates and predicts drywall by at least a decade. Gypsum lath was made in long narrow sheets in which a field of holes was punched. The lathing board was nailed to wall and ceiling framing, much as modern drywall might be but was then covered with lime plaster. This is still done today in better homes where plaster is preferred. I’m on the fence as to how swell I think it is but I do admit to very much liking an imperfectly smooth surface, and drywall just doesn’t do that very well. 

So now, having laid down the history, we can discuss what can be done in your ancient manor. Real plaster that has begun to crack is easily distinguished from drywall, especially along ceilings. Since ceiling joists (usually 2x4s) hang from wall to wall, they tend to sinuate every time a Hummer (or truck) rumbles down the lane. 

Over the decades, they tend to develop fine cracks along the lathing, and if you look carefully you may notice that there are long running cracks about every two inches or so running the length of the room. Sometimes you can only see a few of them, but they still suggest the same effect. 

Plaster, like all things, varies in quality, and some plaster fared well these many decades. Other batches I’ve seen over the years haven’t proven so hearty and it’s quite clear that, in some cases, it was just bad mixing (this is also often true for concrete or stucco). If you have a house that has a lot of loose, cracking and unsightly plaster, I wouldn’t recommend any further patching but would instead beg you bite the bullet and start replacing the plaster with drywall. 

This has some real upside as well, so don’t feel bad. When you take the old plaster down, rather than patching over it, you gain access to the volume of the wall and make electrical work (and other cool things) a practical reality. Let’s take your dining room as a possible starting place (often a favorite). When you remove the plaster and all the old nails, you can easily add plenty of electrical outlets and lighting. 

You can install wall sconces if you like (a common Craftsman era feature) as well as a chandelier, a ceiling fan or recessed lighting. The wiring you connect all these things to can be quickly and cheaply installed because access is so good. Too often I see upgrades to lighting in a room with old plaster and am generally sure that the wiring wasn’t upgraded and may, in combination with bigger light fixtures become a hazard. 

With the wall open, it’s also possible to run speaker wire and install recessed or hanging speakers with hidden wiring. How about smart cable for a flat panel TV or a digital projector? How about phone wiring or a built-in vacuum system?  

A skylight is also easier to install if the plaster is out and sheetrock is going in, and it’s much easier to replace a window if you’re already replacing wall material. 

Taken on a one-room-at-a-time basis, replacement of plaster with drywall is not a huge project and here are some ways to make it even simpler: 

If keeping the job to a minimum is vital, old cracked plaster can be covered over with thin sheets of drywall. Drywall is made in one-fourth and three-eighths inch for just this purpose. Sheets of thick drywall can be screwed to framing directly through the old cracked plaster and then finished with tape and joint compound to create a smoother finish. 

Again, you won’t get a chance to use the full wall cavity, although you can make a lot of holes in the plaster running wiring, and then cover them over with your new layer. Two downsides to adding layers are loss of height or room size and added weight. 

When removing plaster, keep in mind that plaster is extremely alkaline and can cause a burning sensation when inhaled. Old plaster may also contain viral matter and other garbage that we’re better off not breathing, so use of a well-fitting respirator is strongly recommended if you’re involved in the removal process (also goggles, boots and heavy clothing). 

When removing plaster, it’s also a good idea to protect your floors with cardboard or old carpeting. Lime plaster is made using sand, and you can really scratch those old floors up if you don’t take precautions. 

It’s pretty amazing what a project like this can do for your spirits and how much a room can change in this process. My wife and I did this to our own home many years ago and it freed us to change many more things than we ever expected to change: lighting, skylights and even ceiling fans.  

Now I can lie on my couch and stare at the ceiling in the safe knowledge that somewhere, far away, someone else gets to stare at the Grateful Dead instead of me.