New guy taped the whole house with fiberglass mesh tape, including all the inside corners, and bedded everything in lightweight all-purpose.

You're likely to see cracking, particularly at the inside corners, within 90 days.

Why it'll fail:

• Inside corners are stress concentration points. Fiberglass mesh tape has no memory and doesn't form a true tapered joint like paper tape does. It relies entirely on the mud for strength.
• Lightweight all-purpose has lower tensile strength and more shrinkage than standard all-purpose. Combined with mesh tape (which has minimal tensile strength itself), the joint lacks the structural integrity to handle normal building movement.
• Code reference: Per ASTM C840, paper tape is required for inside corners in gypsum wallboard assemblies because it provides the necessary tensile strength. Mesh tape alone doesn't meet this requirement for primary joints.

What you'll see:

• Hairline cracks along inside corners, especially where walls meet ceilings
• Possibly peaking or separation at the tape edges
• Areas where the tape lifts slightly due to poor adhesion under stress

Fix: Remove the mesh tape from all inside corners and re-tape with paper tape bedded in standard all-purpose compound. The flat joints with mesh may hold up better, but inside corners will almost certainly need rework.

This isn't just cosmetic—it's a structural joint failure waiting to happen.

You’re going to see cracked inside corners and popped tape seams, especially at ceiling-wall junctions and long butt joints.

Why:

1. Wrong tape for corners: Fiberglass mesh tape (ASTM C1178) has zero fold memory. It cannot hold a crisp 90° crease. As the house settles and lumber shrinks (typical 1/16"–1/8" per 8 ft), the tape bridges the corner instead of folding. The rigid lightweight mud (ASTM C475) has low flexibility and poor adhesion to the slick mesh surface. Result: hairline cracks down every inside corner within one heating/cooling cycle.
2. Mesh on flat seams: Mesh is permeable. Lightweight mud shrinks ~15–20% by volume as water evaporates. Paper tape absorbs water, swells, and bonds mechanically; mesh does not. Over long butt joints or where framing moves, the mud shrinks away from the mesh, leaving a hollow bond line. You’ll see center-line cracks or "railroad tracking" on butt joints.
3. No chemical set: Lightweight all-purpose is a drying-type compound. It gains zero strength until bone dry. Mesh offers no reinforcement until the mud cures. Paper tape reinforces immediately upon embedding.

The Fix (now, before texture):

• Inside corners: Cut the mesh out. Re-tape with paper tape (crease it first) set in setting-type compound (20- or 45-min, ASTM C475). Top with lightweight.
• Flat seams/butt joints: If mud is still green, peel mesh, re-tape with paper. If rock-hard, skim-coat setting-type compound over the mesh to lock it, then finish with lightweight. Do not rely on lightweight alone over mesh.

Code/Standard: ASTM C840 §7.2 requires tape "suitable for the application." Mesh is listed for flat seams only (per most manufacturer ESR reports); paper is required for corners.