If you own an older house in Central Pennsylvania, there’s a decent chance your walls aren’t drywall. They’re plaster. And if the house is old enough, that plaster may contain horsehair.
Horsehair plaster isn’t automatically a problem. I’ve seen old plaster walls that are still solid after 100 years. I’ve also opened houses where half the wall practically falls off once you disturb it.
The important thing is knowing what you’re dealing with before you start remodeling.
Before drywall became standard, interior walls were commonly built with wood lath and plaster. Thin strips of wood were nailed across the studs, and several coats of wet plaster were applied over them.
The plaster pushed through the gaps between the lath and hardened behind it. Those little hooks of plaster are called keys, and they’re what hold the wall together.
Animal hair was commonly mixed into the plaster as reinforcement — usually horsehair. Think of it as an old version of adding fiber to a building material. The hair helped strengthen the plaster and control cracking while it cured.
When everything is still intact, it’s a surprisingly durable wall system.
When homeowners hear “horsehair plaster,” sometimes they assume the material itself needs to come out. Usually it doesn’t.
If the plaster is flat, solid and well bonded to the lath, there’s no reason to tear apart a perfectly good wall just because it’s old.
The problems start when the plaster has separated from the lath, been damaged by water, cracked badly, or has to be disturbed for the work we’re doing. That’s when an old plaster wall can become much more complicated than drywall.
This is one of the first things I want homeowners to understand. With drywall, I can cut out a damaged section, replace it and finish the joints. Plaster doesn’t always cooperate that nicely.
You might need a relatively small opening for plumbing or electrical work.
You make the cut.
The vibration breaks a few plaster keys behind the wall.
A nearby section was already loose.
Now a 12-inch repair has turned into a four-foot repair.
That’s not necessarily somebody being careless. It’s the nature of working with a wall system that may have been hanging there for a century.
That doesn’t mean we get to use old plaster as an excuse for everything, either. If we know we’re working in a plaster house, the estimate and the plan should reflect that.
If we’re remodeling a kitchen and one existing plaster wall is solid, flat and doesn’t need to be opened, I don’t automatically want to demolish it. Why would we?
Old plaster has some advantages. It’s dense. It’s durable when it’s in good condition. And removing it creates a tremendous amount of mess for no benefit if we’re only replacing it with drywall in exactly the same place.
A ceiling is often the clearest case. If the plaster ceiling and the crown are sound, there is no period-correct way to put them back once they are gone — so unless the work genuinely requires opening them, they stay.
Old doesn’t mean bad.
The decision should be based on its condition and what the project requires.
Localized damage doesn’t always justify replacing an entire room. Loose areas can sometimes be stabilized. Cracks can be repaired. Small openings from electrical or plumbing work can be patched.
There are several ways to make those repairs depending on what’s behind the wall and how much of the original plaster is still sound.
The important part is figuring out whether we’re repairing plaster that’s still attached to the wall, or trying to save something that’s already failing everywhere. Those are two different jobs.
There is a point where trying to save old plaster stops making sense. If we’re doing a major renovation and need access to electrical, plumbing, insulation and framing throughout the room, preserving every square foot of plaster may cost more than it’s worth.
The same goes for walls with widespread failure. If large areas are loose, badly cracked, water damaged or pulling away from the lath, we’re not accomplishing much by making dozens of individual repairs. At that point, removing it and rebuilding the wall may give you a better finished product.
The goal isn’t to save old plaster at all costs. The goal is to avoid tearing out good material unnecessarily, while also knowing when we’ve reached the end of its useful life.
This is where older houses get interesting. You remove plaster expecting conventional framing, and sometimes find something completely different.
We’ve worked on enough older homes to know that you shouldn’t assume what’s behind a wall just because you know how houses are built today.
The house was built according to the materials, methods and decisions of its time — plus whatever five owners did to it afterward. That’s why planning an older-home remodel takes a little more thought.
A house old enough to have horsehair plaster may also have an electrical system that has been modified several times. Maybe the wiring has already been updated. Maybe parts of it haven’t. Maybe somebody updated the visible receptacles but left older wiring elsewhere.
If we’re already opening a significant amount of wall, it may make sense to address electrical work while we have access. The same goes for plumbing and insulation.
That doesn’t mean every old house needs to be gutted. It means opening an old wall should be done with an understanding that the wall itself may not be the only thing we’re evaluating.
There’s no sophisticated way to put this. Plaster demolition is dirty. It’s heavy. It creates a lot of debris.
You’re removing thick plaster plus hundreds of strips of wood lath, often from an entire room. And unlike drywall, you’re not carrying out a few relatively clean sheets. You’re carrying out buckets and piles of broken material.
That affects labor.
It affects demolition time.
It affects disposal.
It affects how much protection the rest of the house needs.
If one contractor prices demolition as if the walls are drywall and another recognizes that they’re plaster and lath, those estimates aren’t necessarily pricing the same job. That’s exactly the kind of difference I talk about in our article on what actually goes into a good contractor estimate .
This deserves some care. Horsehair plaster does not automatically mean asbestos. But an older house can contain other materials from different periods of construction or renovation that need to be evaluated before they’re disturbed. The same is true of lead-based paint in older homes.
The age of the house, the materials present and the scope of demolition all matter.
If there’s a legitimate reason to suspect a hazardous material, the answer isn’t to guess. It’s to identify or test the material as appropriate and plan the work accordingly.
Old plaster is a good example of why a contingency sometimes belongs as a line item in a construction estimate.
We can inspect it.
We can tap on it.
We can look for cracking and movement.
We can identify obvious areas of failure.
But until we start opening the wall, there may be limits to what we can know about the condition of the lath and the rest of the wall assembly. A reasonable amount of uncertainty may belong in the project budget.
What shouldn’t happen is a contractor ignoring the fact that the entire house is plaster, bidding the job like it’s drywall, and then acting surprised when demolition takes longer.
Predictable isn’t the same thing as unforeseen.
What a contingency is, and what it isn’t →
Central Pennsylvania has a lot of older housing. Selinsgrove, Sunbury, Lewisburg, Danville, Northumberland and the surrounding towns all have houses that were standing long before drywall became the standard way to finish walls. Some of those houses are incredibly well built. They just require a different approach.
If you’re planning a remodel in one, I wouldn’t make “does it have horsehair plaster?” the deciding question. I’d want to know:
Then make the decision.
Horsehair plaster isn’t some terrifying material that automatically needs to disappear. Sometimes we leave it. Sometimes we repair it. Sometimes we remove all of it. The right answer depends on the wall and on what you’re trying to accomplish with the house.
What matters is recognizing it before the project starts and pricing the work accordingly.
Because discovering that your 100-year-old house has plaster shouldn’t be the surprise.
The surprise is what we genuinely couldn’t have known until we opened it.
And there’s a big difference between the two.
On the Sunbury bathroom we did both things on the same job. The lower walls came out because we needed access. The top half of the walls, the ceilings and the crown stayed — they were sound, and there is no period-correct way to put that back once it is gone. Demolition still opened cracks in three walls outside the room. We marked each one, patched them, matched the paint, and charged nothing for it.
Fifteen minutes on the phone. You’ll have a realistic range before we hang up — and if we’re not the right people for it, I’ll tell you.