Plaster--Repair What's There?

By: Mark Clement , Contributing Writer
In: Old Houses, Old House Construction, Home Improvement Tips, Old House Musings

We face difficult questions repairing our vintage homes. Should we repair what’s there or replace with new materials and techniques?

This question arises in various forms throughout any old house remodel (from molding to appliances to fenestration), I find it often first pops up when it comes to plaster.

Generally, plaster performs better than drywall because it is more massive: three coats of hand-applied material (brown coat, scratch coat, and finish coat) typically deliver rock-solid, sound-deadening walls and ceilings with a glass-smooth finish–emphasis on sometimes. And whether we should repair or replace a decision blended up with personal and mechanical realities.

Plaster: Repair-Replace-Restore

We’re involved in a piece of history, living in something we love for the pure beauty, experience, or story. And this places us on what I call the repair-replace-restore arc. Some readers (thank you for reading this far!) are pure preservationists and want to repair their homes as they were built. Others want me to skip ahead to gutting crumbling plaster. Still others want to insulate their homes and the plaster prevents it. And so on.

The point is: determine your place along the curve so you can climb the right decision-tree.

Plaster: Repair versus Replace

No matter your personal view of old house repair-restoration the condition of the existing plaster drives the bus.

Worst Case–Structural Damage. Some plaster–regardless if George Washington slept under it–is leaping off the lath (the case in our home.) If your shack has been plagued by plaster-dissolving roof leaks, house settling that pops the lath off the studs or–joy to the world–a billion pock-marks from the birch paneling you removed, the plaster may has been compromised structurally and repairing it means stripping so much of it off you can’t save any. If you’re a preservationist–and have the budget–you’ll go back with plaster.

Awesome! Others, us included, choose drywall (and insulation).

Furthermore, when plaster has been compromised by water, there may be other water-related damage that can only be found by stripping the plaster, like rotted framing (I just found a rotten 4×6 sill plate–it’s bark mulch).

Cracks and Holes. Cracks and holes don’t necessarily mean the entire field of plaster has to go. You can re-attach plaster that’s not too far gone with screws and large washers (I also use truss-head screws) and skim coat the crack with joint compound, paper tape, or gauging plaster. The key here is to make sure you’ve re-attached the loose plaster so the crack doesn’t re-occur.

For plaster that has been locally undermined by water–say under a window–step one is to repair the leak. I’ve repaired plaster with several coats of joint compound or gauging plaster. Sometimes removing loose plaster and “plugging” it with a piece of wallboard is a good way to speed up the application of compound.

Plaster: Decision Tree Rule Of Thumb

True preservationists don’t like it when I say this, but carpenters a hundred years ago would have used plywood and nail guns if they had them.

They would have used drywall too.

The reality is that while plaster–from a purely performance standpoint–is generally better than drywall it is umpteen times more labor intensive and expensive to install putting it so far out of reach of many homeowners that while nice, it’s not a branch on the decision-tree that can be reached.

My place on the preservation arc is that I want to create the right blend of budget, performance, insulation, and execution such that I can keep what’s great about my old home but–like anything that thrives as times change–help it evolve so that it stands the test of the next hundred years.