If you are an interior designer specifying tile in Coral Gables, Brickell, Miami Beach, or Key Biscayne, four design decisions decide whether your install lands on schedule or slips a week. Joint width. Substrate flatness. Edge profile. Mixed-material transitions. None of them appear in the typical FF&E spec, and most installers will not flag them at takeoff because they assume you know.

This guide is the conversation your installer wishes you would have at the schematic stage, not at site walk. It is written for designers who already know their materials and want the install side of the spec — what to put in writing, what to ask the GC to coordinate, and what to leave to the installer’s judgment. Peer to peer.

What a tile spec actually has to tell the installer

A complete tile spec gives the installer five things: the material with manufacturer and SKU, the joint width, the substrate flatness tolerance, the edge profile at every termination, and the transition detail at every adjacent material. Anything missing becomes an RFI, and on a 1620 × 3240 mm Laminam or Neolith panel, an unanswered RFI stops the install.

The NKBA professional standards cover layout, accessibility, and clearances well. They do not cover joint-width tolerance, substrate flatness, or edge profiles in the depth large-format porcelain demands. Those four decisions sit on you, as the designer of record, with the installer as the technical second.

The four decisions that change the install timeline

These are the four spec choices that move the schedule by a week or more on a Miami residential project. Most designers do not see them because installers do not put them in writing.

Joint width — 1.5 mm dry vs 3 mm sanded changes the substrate

A 1.5 mm dry joint and a 3 mm sanded grout joint look like a stylistic choice. They are not. They are different installation classes with different substrate flatness requirements.

A 1.5 mm dry-joint install on a 1620 × 3240 mm slab demands substrate flatness of ± 1.5 mm over 10 ft, per the TCNA Handbook substrate tolerance table for gauged porcelain panels. A 3 mm sanded joint on the same slab can ride on ± 3 mm over 10 ft. On a Brickell post-tension condo deck poured to ± 6 mm over 10 ft, that is the difference between a same-week tile set and a phased self-leveling underlayment pour with a 48-hour cure before the installer can touch the substrate. Our pillar on flatness tolerances for large-format tile lays out the field method we use to map and correct it.

Spec the joint width in your tile schedule. If you spec dry joint, also spec the substrate tolerance. The two travel together.

Substrate flatness — write it into the schedule, not the spec book

The flatness number belongs in the Division 09 schedule and the GC’s site-prep scope, not buried in a Section 09 30 13 boilerplate. If the installer arrives on day one and the floor reads ± 5 mm over 10 ft on a dry-joint plan, the install pauses. We pour SLU. The condo association requires a moisture test before any wet pour, which means another 48 hours and a moisture test on the condo slab before the SLU can be primed.

For dry-joint large-format on a Miami condo, the practical sequence — substrate inspection, moisture testing, SLU pour, prime, layout — is documented in our floor leveling pillar. Pulling that work into the GC’s schedule at schematic prevents the week-long pause it causes when it falls onto the tile installer at install start.

Edge profile — mitred vs Schluter Schiene is a different crew-day

A 45-degree mitred edge on a 12 mm Laminam panel reads cleaner than any metal trim. It also takes a different crew, a different cutting setup, and a longer day per linear foot than a Schluter Schiene profile transition. A mitred edge on a vanity surround or a slab-wall outside corner adds roughly half a day per corner on a residential bath. Six corners is three days you did not budget.

If the look is mitred, spec it explicitly and accept the schedule cost. If the schedule is tight, Schiene in the matching anodized finish reads quietly and lets the install hold its date. Both are correct answers — picking blind is the problem.

Mixed-material transitions — stone-to-porcelain, porcelain-to-wood

Every transition between two materials is a detail decision the installer cannot make alone. A Calacatta marble threshold meeting a porcelain floor needs a height match within 1 mm, a sealant joint for movement, and a profile decision (flush, beveled, T-bar). A porcelain bath floor meeting a wood-floor great room needs a Schluter Reno-T or a flush transition with the wood at the porcelain elevation, which means the GC has to coordinate the wood subfloor height to match the porcelain setting bed.

The American Society of Interior Designers and the AIA contract documents both treat material transitions as a design responsibility, not a means-and-methods item. That is the right read. Put the transition detail on the drawing — section, profile, dimensions, finish — and the installer will execute it. Leave it off and the installer will default to whatever they did on the last project, which may not be your project.

A working spec checklist for designer-to-installer handoff

Submitting a tile spec to the installer is faster when the package is complete. The checklist below is what we ask designers to send before takeoff so we can price and schedule without RFIs.

Item	What to specify
Material	Manufacturer, collection, finish, thickness, panel size
Joint width	1.5 mm dry, 2 mm rectified, 3 mm sanded, or as drawn
Substrate flatness	± 1.5 mm / ± 3 mm / ± 6 mm over 10 ft, by area
Layout	Reference line, starting course, niche centerlines, cut location plan
Movement joints	Per TCNA EJ171 — perimeter and field, by area
Waterproofing	System (Schluter Kerdi, sheet membrane), seam treatment, flood test
Edge profile	Mitred, Schluter Schiene, Jolly, bullnose — at every termination
Material transitions	Section detail at every adjacent floor or wall material
Penetrations	Niches, drains, mixing valves, outlets — with rough-in dimensions
Sealing / maintenance	Sealer, frequency, owner’s manual handoff

When this package lands, takeoff is one site walk and one estimating meeting, not three rounds of clarification. The installer can hold the price and the date.

Where designer judgment ends and installer judgment begins

Some decisions are yours, some are ours, and the trade goes wrong when the line moves mid-project. Keep these in the designer column: material selection, finish, joint width, layout intent, edge profile, transitions, niche dimensions, and the look-and-feel of the finished surface. Keep these in the installer column: trowel selection, mortar coverage, back-buttering, dry-fit sequence, leveling-system spacing, lippage control, expansion-joint placement within the field, and the order of operations on site.

The disputed middle is layout. The right pattern is a layout review before the first cut — installer marks the reference lines, designer signs off, then cuts begin. On a porcelain slab bathroom wall, the layout review takes 45 minutes and prevents the only mistake that wastes a full panel.

Coordinating with the GC and the trades around you

Tile installation lands between five other trades: framing, plumbing rough-in, electrical, waterproofing, and millwork. On a Brickell condo bathroom renovation, the sequencing matters as much as the spec. Plumbing valves set off the layout reference line. Electrical box depths set the panel cut. Waterproofing has to cure before tile sets. Millwork edges meet the tile at a hairline that the designer has to dimension on the drawing.

Build a tile-coordination drawing into your design package. It does not have to be elaborate — a half-scale section through the wet wall, with rough-in dimensions, niche centerline, slab joint, and millwork return, all dimensioned. That single drawing prevents most of the mid-install RFIs that move the schedule.

What a clean designer-installer collaboration looks like in Miami

A clean trade collaboration on a Coral Gables, Brickell, Key Biscayne, or Miami Beach residence has a recognizable shape. The designer issues the spec and the section details at schematic. The GC pulls substrate flatness and waterproofing into the early schedule. The installer prices off a complete package, walks the site with the designer once, and confirms the layout reference lines before cuts begin. Mid-install, the designer walks once more for layout sign-off and once at substantial completion. The installer’s lead — for our work, Ivan — is on site at every walk.

The condo overlay matters here. Most Brickell, Key Biscayne, and Miami Beach buildings impose hours, building-protection rules, and elevator restrictions that affect 1620 × 3240 mm panel handling. The condo bathroom renovation rules in Miami post covers the association-side mechanics. Bring those constraints into the schedule conversation early — they shape the installer’s day, the crew size, and the price.

When to bring The Miami Floors into a designer-led project

We work as the tile installer for interior designers across Miami-Dade and Broward — Coral Gables, Brickell, Miami Beach, Key Biscayne, Pinecrest, Coconut Grove. Trade partners include Schluter (certified), Laminam, Neolith, Guru USA, Sika, and LATICRETE. The firm is Schluter certified.

Bring us in at schematic on any project that includes large-format porcelain slab, bathroom remodeling, or custom shower systems. For the shower waterproofing pillar, the bathroom remodeling pillar, and the large-format porcelain installation pillar, the editorial reading is on the blog. The earlier the install side reads the spec, the fewer RFIs run through the design package, and the more your schedule holds. For the architect-side companion to this post, see our large-format porcelain spec sheet for architects.

Ivan walks every project before sign-off. The designer of record gets the surface they drew, on the date the GC committed.

Reviewed by Ivan Herrera, April 2026.

Working With a Tile Installer: A Designer Guide