Settlement Crack Repair

Cracks Follow the Weak Line

Drywall does not crack randomly. It cracks where the sheet is weakest, and in a framed house that is nearly always the corner of an opening. Look at any wall with a doorway in it and the crack, if there is one, runs up and out at an angle from the top corner of the jamb. That is the point where a full sheet was cut around the opening, so there is less material there to resist the frame racking even slightly.

Windows behave the same way, particularly on a west wall that takes the full afternoon load in summer. Ceilings crack along the joint where they meet a wall, which is a different mechanism entirely and gets its own treatment.

What the Crack Is Telling You

Before anything gets cut or taped we want to know three things.

Direction. A short diagonal out of a door corner is the classic seasonal crack and is usually cosmetic. A crack that runs horizontally along a wall at plate height, or that continues through more than one room in a straight line, is a different conversation.

Width, and whether it changes. Hairline cracks that stay hairline are movement the house has already made. A crack you can get a fingernail into, or one that is measurably wider at one end, is worth more attention.

What the doors are doing. This is the cheapest diagnostic there is and it costs nothing. If interior doors in the same wall still latch cleanly and there is no new gap along the top edge, the frame has not moved much. If a door that used to close now sticks, the frame is out of square and the crack is a consequence.

Why Slab Houses Do This

There is no crawlspace and no wood floor system to take up movement. The bottom plates are bolted straight to concrete. When the soil under an inland slab takes on water through a wet winter and gives it back over a dry summer, the slab lifts and settles by a small amount, unevenly, and the frame goes with it.

That is normal building behaviour in this climate, not evidence of a failure. It is also why a crack repaired badly comes back in the same line the following year, and why we ask whether a crack has been filled before.

The Repair

• Cut the crack back into a shallow V so there is a channel for the tape and the mud to key into, rather than a knife edge that starves the repair.
• Vacuum and dust the channel. Compound over dust is compound that will let go.
• Tape it. Paper tape where the crack is stable and the strongest possible bond is wanted, mesh where the surface is friable or the repair sits over a butt joint.
• Float the finish coats wide. This is the step homeowners skip. A repair floated eight inches either side disappears. One floated two inches leaves a visible ridge that catches light forever.
• Sand, prime the patch so it does not flash under paint, then retexture into the surrounding wall.

When Mud Is the Wrong Answer

Some cracks should not be filled yet, and we will say so rather than take the work.

A crack that has visibly grown in the past year, one that runs diagonally through several rooms in the same direction, or one accompanied by doors and windows going out of square, is telling you the frame is still moving. Repairing the drywall then is cosmetic work with a known expiry date. The right order is to establish that the movement has stopped, then finish the wall once, properly.

The same applies to a ceiling to wall crack that opens in winter and closes in summer. That is truss uplift and it will defeat any amount of tape, because the ceiling and the wall are being pulled apart and pushed back together by a seasonal cycle. The fix is a detail change at that joint rather than a stronger patch.

Doing It Before You Paint

Almost everyone calls about cracks because they are about to repaint. That is the right time. Paint over a live crack lasts a season, and fresh paint makes an old filled crack more obvious rather than less, because the sheen difference across a poorly primed patch shows up in raking light.

Get the movement repairs done, get them textured and primed, then paint the room as one surface.

Call (951) 294-3986.