Patching and Plastering - need help fixing hole
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oldgirl
07-21-03, 04:02 PM
:confused: my house is old and I now have a mid-size hole about (18" x 12") in a wall that made of some kind of plaster, not sheet rock - I tried to make a squar to patch it sheetrock but it keeps breaking -
have any sugestions
have any sugestions
tightcoat
07-21-03, 07:07 PM
To do this with plaster you have a couple of options each has advantages and disadvantages. This is based on the assumption that you have wood lath.
1. You can remove the wood lath between studs and probabaly fill it with drywall and still have sufficient thickness to plaster. Wood lath are 3/8" thick and the plaster is about 1/2" thick. If you cut to the studs be careful that you don't let the lath wiggle or your patch will just get larger and larger. Once you get the lath cut to the studs install a 1X2 board with screws preferably to come flush with the existing edge of the stud. This will be a nailer for your drywall piece. Use 3/8" drywall if you can because then you will have more thickness for the plaster. Plaster that is too thin is weak. If you can't get 3/8" rock I suppose you could recess those nalers a little.
Install the drywall to the nailer with screws. Paint the drywall, any exposed wood lath and the raw edge of the existing plaster with a bonding agent like PlasterWeld by Larsen's Products. There are other brands. Use Gypsolite by GoldBond or StructoLite by USG and mix it with water to a consistency of oatmeal or a little thinner depending on how thick you like your oatmeal. Spread this on and work it well into the lath if any are exposed and grind it into the drywall firmly then spread it on untill it is even with the existing plaster. Then use a straight board and screed off the excess mud until it is flush with the existing plaster. Use the edge of your trowel and your thumb and finger as a gauge and cut the new plaster back about 1/8" a little more or less is OK.
Let this set until it is hard. A little alum in the mixing water and I mean a little like a pinch will help the plaster set.
Once it is set you are ready to finish. Before I tell you how to finish it I have to know what kind fo finish you have. is it textured? smooth, sand finish? I also will tell you the second option but I am out of time for now so wait patiently for the other option and see who else weighs in in the meantime
1. You can remove the wood lath between studs and probabaly fill it with drywall and still have sufficient thickness to plaster. Wood lath are 3/8" thick and the plaster is about 1/2" thick. If you cut to the studs be careful that you don't let the lath wiggle or your patch will just get larger and larger. Once you get the lath cut to the studs install a 1X2 board with screws preferably to come flush with the existing edge of the stud. This will be a nailer for your drywall piece. Use 3/8" drywall if you can because then you will have more thickness for the plaster. Plaster that is too thin is weak. If you can't get 3/8" rock I suppose you could recess those nalers a little.
Install the drywall to the nailer with screws. Paint the drywall, any exposed wood lath and the raw edge of the existing plaster with a bonding agent like PlasterWeld by Larsen's Products. There are other brands. Use Gypsolite by GoldBond or StructoLite by USG and mix it with water to a consistency of oatmeal or a little thinner depending on how thick you like your oatmeal. Spread this on and work it well into the lath if any are exposed and grind it into the drywall firmly then spread it on untill it is even with the existing plaster. Then use a straight board and screed off the excess mud until it is flush with the existing plaster. Use the edge of your trowel and your thumb and finger as a gauge and cut the new plaster back about 1/8" a little more or less is OK.
Let this set until it is hard. A little alum in the mixing water and I mean a little like a pinch will help the plaster set.
Once it is set you are ready to finish. Before I tell you how to finish it I have to know what kind fo finish you have. is it textured? smooth, sand finish? I also will tell you the second option but I am out of time for now so wait patiently for the other option and see who else weighs in in the meantime
tightcoat
07-21-03, 08:25 PM
I'm back
Option 2
This does not involve removing the wood lath, though if you have already done that it will still work. Carefully break off the plaster around the hole by hand. If it will come off by hand it should come off, if you have to pound it or pry it it should stay. Clean the spaces between the lath. It's alright to push it into the wall. Now get some metal lath. A good lumber yard should have it a plaster or masonry supply house will have it. Cut it larger than the hole and use a screw or two not nails to hold it in the middle. Then cut it precisely to fit the hole. Use screws to screw it to studs and carefully to the middle of some of the lath. An alternative to screwing to the lath which sometimes splits the lath is to tie it with soft galvanized wire about 18ga. Make a hook about the width of the lath insert it on one side of the wood lath and back out on the other side then twist the two ends clockwise to tighten and draw the metal lath to the wood lath and cut off the excess. Now if you left the wood lath you can paint the raw edge as described in the previous post and plaster the same way. If you did not leave the wood lath it will take an extra coat. Be sure not to let the new plaster project past the existing and leave it shy all the way around the edges with the new work. What you want to do is put on enough plaster with this coat that you can then fill it flush and cut it back as I described earlier on the second coat. You do need to let the first coat set but it does not need to set overnight or any specific time before the next coat as long as the first coat is hard. I will tell you how to finish in another post when you tell me the kind of finish you have.
Why this lengthy description? If you do it with drywall you will likely be shy on one part and proud on the other and have a wavy patch. This way you can make your plaster exactly fit the existing.
Option 2
This does not involve removing the wood lath, though if you have already done that it will still work. Carefully break off the plaster around the hole by hand. If it will come off by hand it should come off, if you have to pound it or pry it it should stay. Clean the spaces between the lath. It's alright to push it into the wall. Now get some metal lath. A good lumber yard should have it a plaster or masonry supply house will have it. Cut it larger than the hole and use a screw or two not nails to hold it in the middle. Then cut it precisely to fit the hole. Use screws to screw it to studs and carefully to the middle of some of the lath. An alternative to screwing to the lath which sometimes splits the lath is to tie it with soft galvanized wire about 18ga. Make a hook about the width of the lath insert it on one side of the wood lath and back out on the other side then twist the two ends clockwise to tighten and draw the metal lath to the wood lath and cut off the excess. Now if you left the wood lath you can paint the raw edge as described in the previous post and plaster the same way. If you did not leave the wood lath it will take an extra coat. Be sure not to let the new plaster project past the existing and leave it shy all the way around the edges with the new work. What you want to do is put on enough plaster with this coat that you can then fill it flush and cut it back as I described earlier on the second coat. You do need to let the first coat set but it does not need to set overnight or any specific time before the next coat as long as the first coat is hard. I will tell you how to finish in another post when you tell me the kind of finish you have.
Why this lengthy description? If you do it with drywall you will likely be shy on one part and proud on the other and have a wavy patch. This way you can make your plaster exactly fit the existing.