ID plaster type/repair cracks
#1
08-30-16, 11:53 AM
ID plaster type/repair cracks
My 1930s house has developed plaster cracks, plus I need to patch a few holes I drilled looking for leaks/mold. I'm confused about the different types of repair plaster: lime plaster, gypsum plaster, plaster of Paris (still gypsum?). I've even heard some plasters can be fixed with drywall joint compound.
My walls are 3/4" thick: 3/8" plaster coat over 3/8" rock lath. There's a visible paper layer at the mid point.
Given the age (1935) and type (rock lath), what repair materials and techniques should be used to repair the cracks?
My walls are 3/4" thick: 3/8" plaster coat over 3/8" rock lath. There's a visible paper layer at the mid point.
Given the age (1935) and type (rock lath), what repair materials and techniques should be used to repair the cracks?
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#2
08-30-16, 02:41 PM
I generally scratch out the crack and fill it with a setting compound like Durabond.
Can you better describe that or better yet, post some pics.
There's a visible paper layer at the mid point.
#3
08-30-16, 03:14 PM
Can you better describe that or better yet, post some pics.
#4
08-30-16, 03:24 PM
I don't know when it first came out but they used strips of 3/8" drywall for lath before blueboard, perhaps that is what it is. If so, the paper is the face of the gypsum lath.
#5
08-30-16, 04:48 PM
You are describing gypsum plaster over gypsum lath, a very good, durable system.
How wide and how deep are the cracks? Do they follow the lines of the lath?
Put up some pictures of the cracks and we can be specific on the kind of fix.
How wide and how deep are the cracks? Do they follow the lines of the lath?
Put up some pictures of the cracks and we can be specific on the kind of fix.
#8
09-02-16, 08:27 AM
That's decent info 
I've never owned/used a crack opener, the edge of a putty knife or screwdriver has always worked well for me. I don't always tape the cracks as it isn't always necessary although that does provide more insurance that the crack won't come back.
I've never owned/used a crack opener, the edge of a putty knife or screwdriver has always worked well for me. I don't always tape the cracks as it isn't always necessary although that does provide more insurance that the crack won't come back.
#9
09-03-16, 08:42 PM
Good idea EXCEPT screws will not hold in gypsum lath. Where the crack is over a stud they will hold if needed. Countersinking the washer will make for a flat repair. At a cursory glance the rest of the information is right on.
