Patching and Plastering - Odd Drywall Installation Question

I've had my house for about a year, and my wife and I are now replacing the final three windows that were original to the house. All the other windows were done by the previous owner. The house was built in the mid 1950s.

While I removed a couple of the old windows, I noticed the drywall installation was somewhat odd. The back consists of a 3/8" sheet of drywall, and it appears as if there's a 3/8" layer of concrete on top of it. Lastly, a layer of something smooth, presumably joint compound is on top of that and a terrible coat of paint.

I've lived in apartments with horse hair plaster, so this is definitely not that.

Has anyone seen this kind of plastering technique before, and is there anything I should be concerned about with it?

You are describing gypsum lath with gypsum plaster with a smooth, probably whitecoat, a mixture of lime and gauging plaster for the finish. Consider yourself fortunate to live in a house with superior materials.
There are no concerns you need to worry about unless it's lead paint.

Too bad about the paint job.

This house is probably quieter and less drafty than one built with modern conventional drywall. The new windows should be a nice touch.

Tightcoat,

Thanks for the prompt reply. The wall seems to be well constructed, but you can imagine my surprise when I removed the old window to measure the opening and thought "what the hell?"

Patching is going to be somewhat difficult I expect. Upon further inspection of another window frame, I stumbled upon some significant carpenter ant damage. No live ants, fortunately, but I did have to replace one of the window headers which unfortunately required me to remove a good chunk of the upper part of the wall around the window.

I suppose if the wall were standard sheet rock, it would be easier to fix.

Get all the rest of the work done and put up a picture or two and we can tell you a couple different ways to go about fixing the walls. It isn't complicated.

While I removed a couple of the old windows, I noticed the drywall installation was somewhat odd. The back consists of a 3/8" sheet of drywall, and it appears as if there's a 3/8" layer of concrete on top of it. Lastly, a layer of something smooth.





Amazing. I just finished posting about my strange drywall, then scrolled down here and found your post. What is more amazing is that we couldn't get much further apart on this continent, yet the building methods were the same. I live on Vancouver Island, out in the Pacific Ocean.

I posted a pic of the cross section of my drywall. Interested to know if it is the same as yours.

Preservation Brief 21: Repairing Historic Flat Plaster--Walls and Ceilings (http://www.nps.gov/history/hps/tps/briefs/brief21.htm)
Be safe, Gary