There is not much point in just taping over this crack without installing control joints in this ceiling. Still we see an ugly wintertime crack in this ceiling and a noticeable summertime crack as well. This ceiling's gypsum board is nailed to the underside of flat roof rafters spaced 16" o.c., distributing much of the thermal and humidity-related expansion and contraction forces over a large area. Why do we see that the actual ceiling crack is not nearly this wide?īecause the 744 inch long ceiling is not unrestrained while the coefficients of thermal and humidity expansion and shrinkage are for unrestrained gypsum board. We calculate that the total expansion or contraction range force over this ceiling length (744 inches) is about 0.138" (thermal) and 0.145" (moisture) for a total of about 0.28 or 3/10 of an inch - more than a quarter of an inch - more than enough to cause a huge ceiling crack. Using the coefficients of thermal and moisture expansion and contraction in drywall foundĪt PLASTERBOARD EXPANSION COEFFICIENTS, and with a "ballpark" estimate of seasonal temperature variation of 20 degrees and relative humidity variation of 30%, Seasonally as temperatures and humidity vary the width of this ceiling crack also changes from close to hairline (warm humid summer months) to nearly 1/8" in width (cold dry winter months). The ceiling crack shown in our photograph at above right occurs almost in the center of this long ceiling run. The ceiling width is interrupted near one end by the distant partition wall you can see in the left hand photo, but the ceiling continues to open up into another room at that end of the house. Our drywall ceiling photographs above and below show a continuous ceiling that runs the length of this home, or 64 1/2 feet in total distance. Long runs of continuous drywall, especially if more than 30 feet or about 10 meters in its long dimension are likely to suffer expansion/contraction cracking and possibly ridging if control joints are omitted.
#Friday crack open a cold one installIt may be easier to install than paper tape but it is not as strong and is more tear-prone. Control joints may also be needed at common ceiling or wall stress points such as at "L", "T", "U" or "I" shape ceiling or wall intersections like those shown in our sketch above.ĭrywall tape type used for corners: do not use mesh type drywall tape in building corners nor at ceiling/wall joints. Gypsum Board Installation Error contribution to gypsum board cracks & damageĭrywall installation snafus: poor support or connections, over-cuts with a drywall knife at corners of openings, failure to provide for seasonal or other variations in temperature & moisture, improper joint finishing, possibly omission of drywall tape at some gaps, cracks, or repairs.ĭrywall movement control joints omitted on long drywall runs in ceilings (sketch at left) or walls, distances over 30 ft. Causes & Types of Cracks in Drywall, Plasterboard, Gypsum Board Walls & CeilingsĪrticle contents - Causes of drywall or gypsum board cracking, sorted by categories 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. Soil, foundation, and frost problems were causing severe ongoing movement in this structure. #Friday crack open a cold one windowsPhoto at page top: severe settlement cracks around windows in an Alaskan home. #Friday crack open a cold one how toIllustrations show where cracks are most likely to appear, explain why, and suggest both repair approaches to drywall cracks and how to prevent cracking in plasterboard or gypsum board. This article describes the common causes of all types of cracks that appear in drywall or gypsum board or plasterboard walls & ceilings in building interiors. Where, when & why does drywall crack? Coefficients of thermal and moisture expansion & contraction or movement for gypsum board products. We have no relationship with advertisers, products, or services discussed at this website. InspectAPedia tolerates no conflicts of interest.
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