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The Basics of Plaster Repair

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The Basics of Plaster Repair e asics o ASE EAI y aicia ooe Wae amage om umig eak Eecicia amage 4 Ai ' iiscoa eamiaio ae ase Misguie euecoa‘,,,......D Sucua cackig WA IS ASE? ase ecoogy a eciques wou i a ig eook. My uose ee is o eai wa as I o ouses, ase is mos oe a eecoa sysem o e is a wy i ais, a o ouie you oios ime o gysumase, oweae moa a was aie i eaig wi oems. ougou, I assume we oe woo a sis. e is wo coas coai sa a 0% o you ase is saageae i oe (a eas aima ai e iis coa is ie a wos, wee akig aou acig a eai, o em coais o aggegae o ie. e ase coa o ase oiio a eaceme. as a mecaica a aesie o o e a: meca eaig is aice wo make you a asee. ig os, ica oug keys, o aee sums o ase a we eseciay, equie a o o acice wokig wi e ma oug e saces ewee aig sis aesie y i eias. u I ik you e coice a ase is usuay ue o sucio ceae ewee e woo a a we saageae usig sime, ieesie eciques. Ee i ase. youe aeay a eeiece ae o acasee, a Oiousy, ase ca ai ecause o imeecios i ew o e icks o oucs escie i is aice may e maeia ise, o ecause o sesses i o aiue o e ews o you. A e aseig Gossay a aeas e sucua sysem a suos i (ouse amig, sus, o age 4 ceas u couse ocauay o a o us. a. E OOUSE OUA 2 CACKS Hairline cracks are no threat to the integrity of the wall or ceiling, but you'll want to patch them before painting. Open the crack with the point of a can opener or a putty knife, and fill it with spackling compound. Cracks may be cyclical — opening and closing with seasonal variation in humidity which causes the lath to swell and shrink. In that case, it's best to not "spackle" them with rigid plaster. Instead, bed fiberglass tape in joint compound and feather over with more compound. Structural cracks or large cracks usually happen early in the building's life. Dig them out, undercutting slightly to provide a key for the patch plaster. Vacuum out all debris. Patch with the appropriate patching plaster, finish with a layer of compound, sand or sponge, and prime. acig cacks is imecosumig . caassig Wall canvas or modern substitutes are used to line plaster walls before they are painted or papered. (Order it through wallpaper stores.) Decorative painters in the past used to canvas walls before stencilling to protect the fancy painting from hairline cracks. You can use it over patched walls or ceilings, as long as the plaster is basically sound. It's a good way to resurface if you've got less-than-perfect aces, lots of hairline cracks, uneven paint layers, or other minor imperfections. Canvas can't bridge holes or disguise badly uneven patches, however, so do your stabilizing, taping, and patching first. ase wases Plaster washers, also called repair discs or ceiling buttons, are an old-fashioned fix for pulling sound plaster back up to lath (when the keys have broken), or for pulling plaster and lath hack to the studs or joists. They are used in con- junction with flat-head wood screws or drywall screws, and u i you ae em, ey wo come ack. are subsequently covered with joint compound. They're Seeme cacks o e ac aseea ae. e same coe ae acig. 30 MARCH/APRIL 1988 useu o secuig aeas o sou ase eoe you e moe amage ase eay. Ee owe ase ca e sae y acoig i wi ase wases. e ase ise mus ae iegiy — i ca e cumy o so ue o wae amage. I e ase aa assemy ogee as seaae om e suc ue, og woo scews ca e use o go oug e a a io sus o oiss. ase wases may e a o i. We kow o wo comaies a wi si em o you ia maioe: Caes S. Suy Co., 4 Caes S., e. O, oso, MA 024 aseaio, O o 64, e. O, Mae ea, MA 04. ACIG OES I e mie oo a ig, a aea o missig ase was ace wi aiioa eecoa ase (moe o A plaster washer draws cracked plaster to the lath. is ae. Aoe meo o acig oes age a ou ices squae is o use ywa as a ase maeia, as i e oom oo. is meo is usuay easie o o asees — you o ae o uy a mi a owe aiioa aseig maeias. Aeas o a ase ae emoe. e e oe is squae u so a a ea ac ca e cu om ywa o i e oe. Cu e ase ack o sus o oiss so you ae someig o scew e y wa o. e ywall mig ae o e simme o ig i u o e suace o e suouig ase. e ga ewee ac a ase is eae us ike a Seeock seam: ae a iise wi oi comou. You ca skim e eie ac wi comou, oo, i ecessay o ee i o ima a owee iis eue. A aces, ae cacks, a skimme aeas must e ime eoe aiig. Washers secure the remaining old plaster around a hole that has sece o e scew gu been patched. A scew gu comes i ay o isaig o ase wases a ywa aces. y e ime you ag ais io e ywa, e suouig ase wi ae cacke a cume ue. A eis caug ei e ac wi kee i om ayig a, A scew gu is a eecic scewie wi a eacae seee a coos e scew e. Is as, a e e ausme aows eey scew o e couesuk us eow e suace o e ywa wiou eakig e ae ace. u is geaes aaage i ac aseig is a i aois e amme imac a wou amage agie ase. ac aseig e aeaie o e ywa ac is ac aseig. o oes ess a ou ices i iamee, i o oquie ee wi Sucoie o acig ase, a iis (skim wi oi comou. age oes ow o e a wi oay equie ee coas. o e scac a ow coas, use Sucoie egua (USGs eie gysum ase o e equiae. When large chunks of plaster are missing, drywall patches can e o o iis coa is iis ime mie wi gaugig he used as a base. ase. (ee o a ey eaie aice o ow o ac 1■■ E OOUSE OUA 31 plaster in the July-August 1986 issue of OHJ ) Remove damaged plaster very carefully. You can't just bang it out unless you were intending to remove the whole wall and whatever is on the other side of it. Cut it with a chisel and pull it away with your hands. using a prybar gently. Anchor salvageable surrounding plaster with wash- ers as described previously. Resecure loose lath to the studs or joists, predrilling to avoid splitting lath. Vacuum out all debris. We suggest installing metal lath over the wood lath before patching with plaster: this makes the patch less likely to fail. IISCOA AIUE Buckling or delamination of the finish coat of plaster is a common problem in old houses. It can occur because of a bad original bond between the brown coat and the finish ai a ase aiue om wae eeaio. coat. Problems in the manufacture of the raw materials, or with the on-site mixing, application, or humidity, may have interfered with the chemical reaction that causes the plaster to cure. If failure is limited to small areas, joint compound (the restorer's best friend) can be used. Just be sure to remove all areas of loose finish coat, because it wi fail. If delam- ination is extensive, it makes more sense to replaster the finish coat; call in a plasterer unless you're willing to invest some time in learning the skill yourself. AM WAS, WAE AMAGE Plaster that was merely stained by a short-term water leak in the past can be sealed with shellac or a shellac-based primer. But if the plaster lost its integrity (becoming bowed and crumbly), it probably is unsalvageable. Remove only the damaged section, of course. Anchor edges of remaining sound plaster, and patch. Plaster badly damaged by water effloresces. The dry pow- aw maeias a oos o e ae. dery bubbles are salts in the plaster brought to the surface by the water. If it's minor, the efflorescence can be brushed away and the plaster sealed with shellac before painting. More often, efflorescence is not a good sign. Water-dam- aged plaster will not hold paint and, worse, it will even- tually fall. ' .S.4040:• , _ . -. ,.• EUEIIS EMOA ., ,4C 0"ei■..... _ .....4 . aai. W.* 4_. A" ie. p s "or 04INW's 04, • ..4.■ :is. A.......... Textured wall finishes were popular from about 1920 to .464,2:ii 1 0 the late '30s. They're often attractive, in good shape, and 1 0.,.....:. .. 4......0.... part of the character of the house. Then there's the over- done texture finish, sloppily applied and now failing in areas, which was part of a "modernization - of an older house. If you want to remove this stuff, you're in for a lot of work.
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