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Is it desirable to reattach plaster keys when re-insulating attic?
An example of how one little project morphs into several bigger projects...
House in mid-Michigan (42 degrees north latitude, USDA Zone 5), built about 1865 with double-brick walls, plaster on interior of brick walls. Previous owner installed ceiling fan in second floor bedroom, fan no longer works (even after I replaced its internal switch) and I decided to replace it with a new fan. Easy project, right? I removed old fan from ceiling, discovered no electrical box available and previous owner instead ran electrical wire through hole in plaster ceiling and used a drywall screw to attach the fan to a solitary 1-inch x 6-inch ceiling joist. OK, now I'm up in the attic with idea of installing a metal electrical box that attaches to two of the ceiling joists. I've cut down two 4-foot long 1x8's to same depth as the 6-inch ceiling joist, and screwed them as sisters to the ceiling joists. Hopefully this will give me adequate support for the 15 pound fan.
While up in ye old attic, couldn't help but to notice the attic floor has only 2-inches to 2.5-inches of poured-in loose insulation (white-colored cotton-like material, possibly mineral wool?). OK, now the fan project morphs into a re-insulating the attic floor project. My plan is to remove all of the loose poured-in insulation, and replace it a layer of 6-mil polyethylene vapor barrier draped over the joists and topped with sheets of blue-colored Dow styrofoam insulation in the joist bays, which should give me R=30 insulation (R=5 per inch). I still am undecided about installing foil-surfaced styrofoam sheet beneath roof decking as a radiant barrier. [Note: your suggestions about attic insulation are welcome.]
Anyway, since I'll be brushing away the old insulation from the attic floor, the broken keys of ceiling plaster between the wood lath will be exposed. Is there any advantage to re-attaching the broken keys? What material should be used? (I'm guessing that merely flooding the joist bays with gypsum wallboard compound might be too heavy for the ceiling below, and I'm uncertain if modern gypsum material is good choice for adhering to what might be old lime plaster.) All of this might be a moot point, because the previous owner screwed on a new plasterboard ceiling and coated it with roughly-textured paint in swirl pattern (probably to hide amateur taping job of wallboard joints, textured paint can cover a multitude of sins). I consider swirl-textured paint to be an abomination to the historic fabric of the house, but I'm willing to tolerate a ceiling fan.
Your suggestions are welcome.
House in mid-Michigan (42 degrees north latitude, USDA Zone 5), built about 1865 with double-brick walls, plaster on interior of brick walls. Previous owner installed ceiling fan in second floor bedroom, fan no longer works (even after I replaced its internal switch) and I decided to replace it with a new fan. Easy project, right? I removed old fan from ceiling, discovered no electrical box available and previous owner instead ran electrical wire through hole in plaster ceiling and used a drywall screw to attach the fan to a solitary 1-inch x 6-inch ceiling joist. OK, now I'm up in the attic with idea of installing a metal electrical box that attaches to two of the ceiling joists. I've cut down two 4-foot long 1x8's to same depth as the 6-inch ceiling joist, and screwed them as sisters to the ceiling joists. Hopefully this will give me adequate support for the 15 pound fan.
While up in ye old attic, couldn't help but to notice the attic floor has only 2-inches to 2.5-inches of poured-in loose insulation (white-colored cotton-like material, possibly mineral wool?). OK, now the fan project morphs into a re-insulating the attic floor project. My plan is to remove all of the loose poured-in insulation, and replace it a layer of 6-mil polyethylene vapor barrier draped over the joists and topped with sheets of blue-colored Dow styrofoam insulation in the joist bays, which should give me R=30 insulation (R=5 per inch). I still am undecided about installing foil-surfaced styrofoam sheet beneath roof decking as a radiant barrier. [Note: your suggestions about attic insulation are welcome.]
Anyway, since I'll be brushing away the old insulation from the attic floor, the broken keys of ceiling plaster between the wood lath will be exposed. Is there any advantage to re-attaching the broken keys? What material should be used? (I'm guessing that merely flooding the joist bays with gypsum wallboard compound might be too heavy for the ceiling below, and I'm uncertain if modern gypsum material is good choice for adhering to what might be old lime plaster.) All of this might be a moot point, because the previous owner screwed on a new plasterboard ceiling and coated it with roughly-textured paint in swirl pattern (probably to hide amateur taping job of wallboard joints, textured paint can cover a multitude of sins). I consider swirl-textured paint to be an abomination to the historic fabric of the house, but I'm willing to tolerate a ceiling fan.
Your suggestions are welcome.
Replies to This Discussion
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Permalink Reply by Me on -
Isn't it amazing how one thing leads to another?
I am not aware of any practical method of reattaching the broken keys to the plaster. As plaster cures it goes through a process similar to curing cement. The integrity of the plaster is achieved during this curing. Once the hardened plaster is broken it generally cannot be "reattached". Plaster is a lot stronger then it seems. A few broken keys are usually not a big deal. Often when a key is broken the plaster still has a certain amount of "grip" on the laths where the plaster had extruded through the lath. This is usually enough to hold the plaster in place. If the plaster has started to pull away from the laths then a repair is necessary. This type of repair can occur in a number of ways depending on your circumstances and the condition of your plaster.
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Permalink Reply by Clarence A Bauer on -
Yes you can reattach plaster to wood lath.
I have used this type product many times in the last 20 years.
Try this site www,plastermagic.com it works very well.
You can also mix your own use the following
4 parts hydrated hydraulic lime (NHL-3.5)
1 part fine silica sand
4 parts ceramic microspheres ( ES-300 )
4.5 parts 10 persent acrylic ( Rhoplex MC-76 ) in water.
there are also others that will work.
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Permalink Reply by John Leeke on
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Permalink Reply by Clarence A Bauer on
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Not sure who formulated this recipe?
If you need that info you may want to check out one of the following.
Frank Matero American Institue for Conservation (AIC)
Also try Joe Oppermann AIA Last contact i had with him was Sept. 2000
I did use this recipe or one very close to it on a project in 2000
Also am looking at this recipe in a set of Specifications dated 2009
Also have used Rory Brennan"s Big Wally's Adhesives they work very well used it on 1800 plaster on wood lath saved about 90% of the original plaster.
I have also used the recipe designed by Phillips Morgan " Adhesives for the reattachment of loose plaster" this works but is not as user friendly as the Plaster Magic.
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Permalink Reply by Larry Ashurst on -
If it's covered in plasterboard, the broken keys won't matter as the plasterboard should be fixed to the joists. If it was just some keys broken, you could cut away the broken area and repair it or dampen the area from above and spray the area with expanding foam to adhere the plaster to the lath. I'm in the UK, so some of my terms may be different to yours.
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Permalink Reply by Italianate in Ionia on
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Yes, the new plasterboard is screwed to the joists and lath. But I am not happy with the textured paint they applied to the new plasterboard. I am tempted to remove the new plasterboard "someday" and repair what remains of the original plaster, but that will be a major undertaking. My thoughts are: if I'm already in the attic (removing the shallow depth of loose-fill insulation) and have good access to the original plaster keys, would it be worth the effort to add some sort of binder that reinforces the deteriorating plaster keys so I'm ready to remove later the plasterboard? From what I've seen thus far in the attic, the keys have been broken in numerous areas (probably the reason they installed the new plasterboard). Should I try to return the house to its original condition, or should I learn to love the plasterboard overlay, or should I rip out everything down to the studs/joists and install modern perforated metal lath with new plaster?
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Permalink Reply by Ingalls DeMars Painting on
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Permalink Reply by John Leeke on
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If you have back issues of OHJ, check out my Saving Irreplaceable Plaster article in the Nov.1987 issue. Instead of using the adhesives mentioned in the article use Rory Brennan's Plaster Magic products, they are formulated especially for this method of injected adhesive bonding. But remember, no products are "magic", success is in the method, not the product. Since 1982 I've used a wide range of adhesives for this method and most all of them have worked well.
John
www.HistoricHomeWorks.com
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Permalink Reply by Italianate in Ionia on
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Are 20-years-old back issues of OHJ still available?
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Permalink Reply by John Leeke on
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Not from the publisher (I suppose), check your library or any long-time old-house nut who probably has a full set of issues squirreled away on the top shelf in the back pantry.
That article may have also appeared in the Old-House Journal Compendium, could someone who has a copy check that?
bright-eyed & bushy-tailed,
John
www.HistoricHomeWorks.com
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