A prospective client today was expounding to me about the insulative value of lath and plaster. I didn’t contradict him, but that was a new one to me. In older home remodels, I am always advocating replacing old lath and plaster for drywall. Am I missing something, Piffin?
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Replies
I think it is your client who is missing something - whatever used to be where that hole in his head is.
Both have R-values around .5/inch.
Since the normal thickness averages 5/8" or less, that means an R-value of about .25.
Even if one is better insulation than the other the percentage of .25 in a typical wall is worth about as much as a sheet of cardboard.
'course there are people who will swear that cardboard is fine insulation...
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Depending on the method of application, plaster can have a thickness in excess of an inch. Add rock lathe to that and you could be up to an inch and a half without much difficulty.
If your view never changes you're following the wrong leader
Maybe he was thinking about the thermal mass of plaster, which can be pretty good, but as you know that's a totally different animal from insulation.
Billy
Yeah, plaster is a lousy insulator but has a lot of thermal mass. It also, if sound, is very "tight" and inhibits air infiltration pretty well (though air can still infiltrate through outlets, around door/window frames, etc). Thermal mass and low infiltration can make an uninsulated house a lot more comfortable in the right circumstaances, though certainly good insulation will make it more comfortable.