Not for uncalibrated, handmade, pressed, or quarry-class tile — variation at this width goes straight into the lines, and that tile's correct home is the wide rung built to absorb it.
Not for wavy substrates: no joint hides lippage here, and a spacer lifts nothing — flatness is bought at the substrate stage or not at all.
Not with sanded grout — bridging voids the fill at a sixteenth; unsanded only.
Not for lugged wall tile or sheet-mounted mosaic, which space themselves — the line's two no-sales hold at every rung.
Not a movement joint — perimeters are caulked, never grouted, and a hairline field makes the flexible perimeter more visually important, not less.
at 1/16" your hands catch lippage before your eyes do — sweep every fresh course; press corrections while the bed is live. Rake as you go: squeeze-out owns hairline joints that aren't cleaned by course's end — a spacer leg dragged down the joint is the free tool for it. Favor the tombstone: standing placement, two per side, straight vertical pulls ⚑(shape flag stands) — the flat cross is this rung's avoidable regret. Raking light is the inspector: a work light held low across the field, every few courses, shows the plane the way the bathroom's window will — find proud edges wet, not at punch-out. Save the audit evidence: the tile boxes' calibration/rectification labeling is the record that says the field qualified — worth a photo before the boxes leave, for the day a question arises.
Asked at the counter
BUYER QUESTIONS ANSWERED BEFORE THE CART, NOT AFTER THE RETURN
Can I use 1/16" spacers with regular (non-rectified) tile?
Run the stack test in 2a — face-to-face stacks that stand flush qualify; visible stagger means the variation will bend your lines, and 1/8" is the honest answer. Rectified or tightly calibrated tile is this rung's intended partner.
Sanded or unsanded grout at 1/16"?
Unsanded, without exception — sand grains bridge a hairline joint and void the fill. This is the mirror of the wide rung's rule, and the bag's own instructions govern its product.
Why does everyone warn about lippage at tight joints?
Because a narrow joint has no ramp: adjacent edges meet almost directly, so any height difference is caught by raking light and bare feet — the two inspectors that visit every floor daily. Flat substrate first, or a wider joint.
Will the tight joint work over my existing floor if it's "pretty flat"?
Put a straightedge on it and believe the straightedge, not the adjective. Daylight under the edge now is lippage underfoot later — flatten first, or step up a size.
Flat crosses or standing at this width?
Standing, two per joint side (cross form assumed) — a flat cross at the bottom of a sixteenth joint is close to unretrievable at pull time, and everything on this page depends on every spacer coming out.
The thinset keeps filling my joints — normal?
At this width, yes, and it must be raked out every course before it skins — a joint full of cured thinset has no room for grout. Squeeze-out management is the hairline joint's signature chore.
Is the seamless look worth it?
On qualifying tile over a qualifying floor, genuinely — it is the best-looking joint in the store. The audit costs ten minutes; run it before the bag goes in the cart.
