What causes cracks between the wall and ceiling?

Monday, August 5, 2019

Jan 14, 2016 - Fixing a drywall crack at the wall/ceiling joint will improve the looks as well as the structural soundness of your room. Drywall is a construction panel made from gypsum plaster and thick sheets of paper that is then dried in a kiln. Repairing Cracks in Walls The best way to repair a crack in drywall is to re-tape the joint. This involves scraping away the loose tape and crumbled bits of drywall mud, sanding the surface smooth. What causes drywall crack at ceiling tape joint? Entire length of joint. A type ceiling meets flat ceiling joint is 14 feet long. Joint is cricket entire length on both edges of tape. House is 8 years old. Fixing a drywall crack at the wall/ceiling joint will improve the looks as well as the structural soundness of your room. Drywall is a construction panel made from gypsum plaster and thick sheets of paper that is then dried in a kiln. Drywall is easier to install than traditional plaster, and is easier to repair or replace as needed. Place a drop cloth along the floor at the base of the wall in case any drywall or paint falls.

Cracks along the line where the ceiling and interior walls meet can be caused by settlement of the floor slab, but usually there is a separation between the baseboard and floor first, along with stress cracks emanating diagonally from the corners of doors, before any ceiling/wall crack lines appear.

If the cracks are just along the ceiling/wall line, and your roof structure is wood trusses, it is likely due to truss uplift. These cracks usually occur during the winter, and close back up during the summer, because they are thermally induced. Due to the mild winters in most of the southern two-thirds of Florida, it is more likely to occur in North Florida and during a harsh winter.

What happens is that the bottom chord of the truss bows upward during cold weather, pulling the ceiling up and away from the walls. To understand why, you first need to know that wood expands and contracts more in relation to moisture content than temperature. As a percentage, expansion/contraction is significantly higher perpendicular to the grain than along the the grain. But because the length of the truss lumber is many times the width, and the chord members more constrained in length than width by the truss plates, the movement with the grain (along the length of the lumber) is the more significant issue with trusses.

During the winter months the bottom chord of the truss in buried in ceiling insulation, warm and dry. The top chord and web members in a ventilated attic are exposed to the high relative humidity of cold air and possibly occasional condensation. So they have a high moisture content and expand, while the dry bottom chord contracts. Because the bottom chord is secured at both ends to the bearing walls and cannot move laterally, the result is that the expanding top chord and web members pull the bottom chord upward, making it bow, as shown by the dotted lines in the diagram above.

Truss Uplift Repair

This is not a structural problem. It is only cosmetic, but nobody wants unsightly cracks at their wall/ceiling line. There are several solutions that do not stop truss uplift, but keep it from becoming a problem. Unfortunately, the various recommended fixes should be done at time of construction, and are difficult and expensive to retrofit.

• Install an inverted “L” angle clip, with the verical side nailed to the top plate, and the horizontal side resting on top of the ceiling drywall, with no ceiling nailing of the drywall close to the corner, so the corner stays intact and the drywall can flex slightly upward when the trusses bow.
• Secure drywall to the top of the wall, but not to the trusses for a distance of 18” away from the walls. Another way to let the corner flex a little.
• Install decorative cove molding where the walls meet the ceiling, and fasten it to the ceiling, but not the walls. So the crack between wall and ceiling is hidden by the sliding cove molding. This is the one fix that is comparatively easy to retrofit, but do not paint the walls in the summer, to avoid having an unpainted stripe around the room when the molding rises during the winter.

One last thing that can cause ceiling cracks at the wall is sagging drywall, usually due to high humidity and corroded fasteners. This is most likely to happen in a garage because it is an unconditioned space and, also, cracks along the seams of the drywall panels perpendicular to the wall are likely to appear before the cracks along the wall. To read more about it, see our blog post Why is my garage ceiling sagging?

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Here’s links to a collection of our other blog posts about STRUCTURE AND ROOMS:

•Why is the grout cracking and coming loose at my floor tile?

•What are the building code requirements for notching and boring holes in a wall stud?

•What causes dark or light 'ghost' lines on ceilings and walls?

•Can you access or exit a bedroom through another bedroom?

•What is the difference between a carport and a garage?

•What are simple ways to find the cause of a ceiling stain?

•What is the minimum size of habitable rooms in a house according to the building code?

•Why is my garage ceiling sagging?

•How can I identify what kind of wood flooring I am looking at?

•Why does my concrete floor slab sweat and get slippery?

•What is the minimum ceiling height for rooms in a house?

•Why are there score line grooves in the concrete floor of the garage?

•How much can I cut out of a floor joist?

•How can I tell if my floors are sloping?

•Why do the floors slope in this old house?

•What are the common problems when a homeowner converts a garage to conditioned living space, such as a family room?

• How can I tell if a wall is load-bearing? Which walls can I take out?

Visit our STRUCTURE AND ROOMS page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

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Cracks in ceilings may be cosmetic or they can be a structural “red flag”. The difference depends on the shape, size, location, and the cause of the cracks.

Often we don’t even realize there are cracks and when we do notice them, we don’t know how old they are; did they just happen, or have they been there for years? Once the cracks are noticed, then it’s a good idea to do a little investigation into them. It is not uncommon for homes to get a crack or two in their ceilings over time, therefore older homes will generally have more ceiling cracks.

New homes will often develop a few cracks in the first year or two, but most of them will be at door and window corners or at the areas where the walls meet the ceilings, rather than on the ceiling itself. One of the common reasons for this is that many homes will settle a little in the first year or two. Also, the wood framing lumber usually drys out some which causes the studs, joists, and rafters to twist or bow slightly. Major track builders know that they will get a number of calls about these cracks in the first year or two and just consider it part of the construction business.

Hairline and spiderweb type of cracks

Hairline type of spiderweb cracks due to paint issues

When repeated coats of paint are applied over other coats, then over a period of years, the chances of crazing (a pattern or network of hairline/ fine cracks) or alligatoring (a pattern similar to the reptiles scaly skin) cracking increases.

The layer(s) under the topcoat get brittle over time and expand and contract due to thermal and moisture changes differently than the more flexible topcoat. These lower coats tend to crack first and then the cracks work their way up to the topcoat, thus patterns of thin cracks develop in the topcoat of the paint.

Spiderweb or hairline type cracks due to drywall mud issues

At drywall joints where two pieces of drywall butt up to one another, drywall installers tape the joint areas. Drywall tape is used as well as drywall joint compound, often called drywall “mud”. If the drywall joint compound is put on in one or more coats that are too thick then when the mud dries, it shrinks, creating hairline spider or crazing type cracks. When too much water is added in order to thin the mud prior to application, small hairline cracks may also occur. These types of cracks are merely the result of poor workmanship.

Straight cracks at taping joints

Cracks that appear at the side of drywall joint tape are usually caused by improper mud application during the installation. When the drywaller taped the joint they did not use enough mud and this can result in shrinkage cracks along the tape lines.

Usually, the crack will be very straight because it is following the straight edge of the tape at a drywall joint. This is insignificant for structural concerns and is instead evidence of poor workmanship.

Cracks on a sagging or bowed ceiling

If a ceiling is bowed, sagging, or dropped down, then the reason may relate to structural issues. Common causes include:

1. Spacing of ceiling joists or trusses

If the ceiling joists or trusses supporting the ceiling drywall are spaced too far apart, then sagging may result and the stress from this may create cracks.

2. Improperly sized ceiling joist

When the ceiling joists or trusses are undersized for the drywall ceiling weight that they are carrying, then sagging may result and the stress from this may create cracks.

3. Damaged ceiling joists or trusses

Occasionally, a ceiling joist or a truss becomes damaged or cracked, this weakens the framing member and the ceiling will bow or sag in one or more areas. Thus, stress is placed on the drywall and cracks develop.

Cracks caused from a load-bearing wall being removed and not having proper supports installed

Bowed ceiling cracks may also be caused by a load-bearing wall being removed without the proper structural support being added. At times the ceiling may not be bowed, but one section has dropped down. This movement can result in cracks. Read more on load-bearing walls.

Cracks caused by truss uplift

Cracks that appear where a ceiling intersects a wall may be due to “truss uplift”. Roof trusses tend to move a little when there is a seasonal change of temperature or humidity. These fluctuations and changes may result in the trusses moving or shifting a little. This is common and most homes are engineered to handle movement due to truss uplift.

Truss uplift cracks are normally noted on interior walls, not exterior walls. The cracks will typically appear on walls that are perpendicular to the direction that the trusses run. Generally, these cracks are not considered to be a structural concern and may even open up and close somewhat depending on the season. Read More On Truss Uplift.

A higher level of concern with ceiling cracks occurs when:

A crack is continuous through the wall and ceiling

Cracks that run across the ceiling to the wall and then down on the wall, basically a continuous crack going through the ceiling and the wall, may be a concern. This type of crack suggests that there may be a structural issue i.e. a foundation or framing issue.

Ceiling cracks running diagonally across the ceiling

A crack (of a 16th of an inch or larger) that runs at a diagonal angle through a sheet(s) of drywall requires a lot of force to create this crack. It’s like the drywall is ripped apart. This type of crack generally would be considered a “red flag”, depending on width, length, and location.

Wide cracks and areas that have a number of cracks

Ceilings that have multiple cracks that are more than just a small hairline crack are a concern. Cracks that are 1/8 or 1/4 of an inch wide or more would easily fall into this category. A crack that is 1/8 inch wide and only two feet long in a corner will not be given as much weight as a ceiling with 1/4 inch wide cracks, three or five feet long and that appear in a number of locations.

Ceiling cracks become more of a “red flag” if there are other signs that the house may have movement or structural problems

When ceiling cracks become a concern you should look for other factors that indicate possible structural issues to determine the severity and importance of the ceiling cracks.

Signs of possible structural issues include:

• Cracked foundation or slab (Read more)
• Sloping or sagging floors
• Doors and windows that stick or won’t open
• Sagging roof

Cracks may also be caused by:

How To Repair Crack Between Ceiling And Wall

• Small earthquake tremors
• Settling of the home
• Soil movement from slope creep or landslides
• Sinkhole issues

Bottom Line

Ceiling cracks are common and usually not a major concern. The older the home, the more likely for cracks to appear. Most contractors and homeowners will view cracks as a maintenance or cosmetic issue. Occasionally ceiling cracks can be a “yellow” or “red” flag that there is a serious or structural issue, therefore it is good to be able to recognize warning signs that a problem may exist.

If you are unsure if there is a problem or if a ceiling crack is serious, a home owner or buyer may wish to consult with an appropriately qualified professional. This may be a framing, drywall, or general contractor. A structural engineer likewise may be helpful in providing meaningful information.

• You may only need preventive maintenance
• If very minor, then you may just need to monitor it for changes
• If repair is needed, it is much cheaper to correct it in the early stages than after it has become a big problem
• Should it be major, then you may need to consult a qualified professional

Take a minute and review our page with other common structural issues in homes

Articles and Resources On Common Structural Issues In Homes

Crack At Ceiling Wall Joint Repair

Additional Resources

Crack At Ceiling Wall Joint Removal

• Cracks develop in wall and ceiling areas. What are they a sign of and what can be done?

• Contractors will tell you that concrete cracks; well likewise, stucco tends to crack. There are several things...

• If a load bearing wall is removed, there are structural issues and risks that homeowners and buyers should be aware of.

• Settlement may cause damage to a house, but some settlement can be prevented or reduced.

• Floor creaking may be related to the installation of the floor or to the homes foundation settling. Other reasons include...

• If your foundation has a crack or cracks know what to look for to determine if they are major or minor.

• Sloping floors are often one of the warning signs that structural engineers look for when analyzing a house.

• Doors that self close or open is usually not due to a ghost. First check if floor is level.

• Can you name the type of foundation that you have?