![]() proper frame spacing and application proceduresī. Remedy: remove sagged board or fur ceiling using RC-1 Resilient Channels and apply another layer of board. Also caused by installing board too thin for framing spacing. Cause: too much weight from overlaid insulation exposure to sustained high humidity vapor retarder improperly installed or wetting causes ceiling panels to sag after installation. 339, USG describes a cause of ceiling panel sagging but does not address the identical bulging in wall panels:Ī. Indeed in their Gypsum Construction Handbook, 2d ed. While it's natural to suspect weight-driven sagging on a bulged plaster ceiling, gravity cannot not explain the roomwards bulge of the same pattern in a gypsum-lath wall. The identical bulging pattern appears on a vertical surface, with the convex side of the bulge facing into the room. Take another look at our bulged wall photograph above.Īnd check the Carson Dunlop Associates (found at page bottom, Click to Show or Hide) explanation of the shadow effect on building walls (left). OPINION-DF: The SmartTrack explanation above leaves us a little unsure of the sagging plasterboard diagnosis even though we agree that visually, it's a "sag". Doubts about plaster shadow sagging cause & a vote for bulging The ceiling shown above was found in home built in the 1940's. Compare bulged pillowed plaster ceiling with sagged 16 x 32-inch ceiling tiles?Īt ASBESTOS CEILING TILES - in the article FAQs section we discuss the possibility that the material shown at left, apparently 16" x 32" water-damaged ceiling tiles may contain asbestos and what to do about it. Sometimes seams are also visible perpendicular to these, at thirty-two or forty-eight inch intervals. The result is a pattern visible in the wall or ceiling that shows seams every sixteen inches in one direction. The moisture was driven back into the gypsum lath which sagged. The finish coat was sometimes applied before the first coat dried completely. ![]() This was created when the plaster was applied too quickly. Shadow Effect A common problem with plaster applied over gypsum lath is the shadow or bulge effect. From the ASHI SmartTrack lesson on this topic Hankey quotes: ![]() Here is the image for the "pillow effect" ceiling from the rock lathe panels. Hankey includes the following explanation: Shadow Effect in Bulged Plaster CeilingsĪSHI home inspector Roger Hankey has provided us with the image of regularly-bulged rectangular plaster ceiling panels shown at left in a home built in 1947. Minnesota inspection expert Roger Hankey has provided our next photograph, below, where the oblique light source was from a window at the right side of the picture. More about using oblique light to find building conditions is In this photo you can see the convex vertical plaster wall bulges and the indentations at the plaster lath-board points of nailing to the wall studs. If you shine a flashlight along, rather than directly at a wall surfaces, both regular details (such as regular, rectangular bulges in a plaster wall or ceiling) as well as irregular surfaces and defects are easily observed. The building owners were concerned for possible exterior leaks into the wall cavity and a hidden mold problem.īecause the home had experienced leaks in other areas and had other mold problems we investigated further.īut the bulged wall problem in this case was essentially a cosmetic one identified and described as plaster wall shadow effect discussed below. Shadowing bulged walls traced to gypsum lath installation: as our photos show, below, the wall in this New York home was bulged in a regular rectangular pattern. ![]() How to Identify & Diagnose Pillow Effect Bulging Found on Plasterboard Lath (Rock Lath) Ceilings & Walls We also provide an ARTICLE INDEX for this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need. Page top photo provided courtesy of Minneapolis home inspector Roger Hankey. In this article series we describe and discuss the identification and history of older interior building surface materials such plaster, plaster board, split wood lath, sawn lath, and expanded metal lath, Beaverboard, and Drywall - materials that were used to form the (usually) non-structural surface of building interior ceilings and walls. Here we provide a photo guide to identifying types of plaster installed in buildings, using building ceilings as a photo and investigation guide. We have no relationship with advertisers, products, or services discussed at this website.ĭiagnose rectangular bulge pattern in plaster ceiling or wall surfaces: InspectAPedia tolerates no conflicts of interest.
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