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100+ Free ACT Mud Floors Practice Questions

Pass your Advanced Certifications for Tile Installers (ACT) — Mortar (Mud) Floors exam on the first try — instant access, no signup required.

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How is the correct water content of deck mud judged in the field?

A
B
C
D
to track
2026 Statistics

Key Facts: ACT Mud Floors Exam

25 MC

Written Exam Questions

ACT Consortium

84% / 85%

Written / Hands-on Passing

ACT Consortium

1:5

Deck Mud Cement-to-Sand

ANSI A108.1A

1-1/4 to 2 in

Unbonded Mortar Bed

TCNA F112/F121

1/4 in/ft

Min Slope to Drain

TCNA Handbook

100 Q

Practice Questions

OpenExamPrep

ACT Mortar (Mud) Floors validates that a CTI or IUBAC journeyman can correctly float an unbonded mortar bed: 4-mil poly cleavage membrane, 2x2 16-gauge WWF reinforcement, deck mud at 1:5 cement-to-sand, 1-1/4 in to 2 in thickness, 1/4 in per foot slope to drain, long straight-edge screeding with wood float and steel trowel, perimeter and field movement joints per TCNA EJ171, and 24-72 hour cure before tile-setting. Two-test format: 25-question written (84% pass) plus a field test (85% pass).

Sample ACT Mud Floors Practice Questions

Try these sample questions to test your ACT Mud Floors exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Which TCNA Handbook method describes an unbonded (floating) mortar bed over a concrete substrate for interior floor tile without a topical waterproof membrane?
A.F112
B.F121
C.F122
D.F125
Explanation: TCNA Method F112 is the standard unbonded mortar bed over a concrete substrate for interior floors. A cleavage membrane separates the bed from the slab and the bed is reinforced with 2x2 wire mesh.
2Which TCNA method adds a waterproof membrane to the unbonded mortar bed assembly over a concrete substrate?
A.F112
B.F121
C.F125A
D.B415
Explanation: TCNA F121 is an unbonded mortar bed over concrete with a waterproof membrane placed beneath the cleavage membrane. It is used where moisture from above or below must be contained.
3What is the primary purpose of a cleavage membrane in an unbonded mortar bed assembly?
A.Waterproof the substrate against vapor drive
B.Allow the mortar bed to float independently of substrate movement
C.Increase compressive strength of the mortar bed
D.Provide a vapor retarder for radiant heat
Explanation: The cleavage membrane breaks the bond between the mortar bed and the substrate so the bed can move (or stay still) when the slab cracks or shifts. This isolation is the defining feature of the F112/F121 floating system.
4Which material is most commonly specified as a cleavage membrane in a TCNA F112 unbonded mortar bed?
A.4-mil polyethylene sheet
B.Self-adhered SBS membrane
C.Silicone waterproof coating
D.Cementitious crack-isolation membrane
Explanation: TCNA specifies 4-mil polyethylene sheet (or 15-lb roofing felt) as the cleavage membrane. Its function is to act as a slip sheet — not a waterproof or anti-fracture layer.
5Which reinforcement is specified within an unbonded mortar bed per TCNA F112?
A.#3 rebar at 12 in on center
B.2 in x 2 in 16-gauge welded wire fabric or equivalent
C.Carbon fiber strands at 6 in spacing
D.Polypropylene fibers blended into the mortar
Explanation: The mortar bed is reinforced with 2 in x 2 in 16-gauge welded wire fabric (WWF) — or an equivalent galvanized expanded-metal lath — placed near mid-depth of the bed.
6Which TCNA Handbook method places thinset over a waterproof or anti-fracture membrane on a concrete slab — not a floated mortar bed?
A.F112
B.F121
C.F122
D.F121A
Explanation: F122 is a thinset method bonded to a sheet-applied waterproof or anti-fracture membrane over concrete. It is not a thick mortar bed assembly.
7Which TCNA method is used where crack suppression must be provided only over existing in-plane cracks, not the entire floor area?
A.F125
B.F125A
C.F122
D.F121
Explanation: F125 applies a crack-suppression membrane locally, over existing in-plane cracks. F125A uses a full-area crack-isolation membrane.
8On an F112 unbonded mortar bed, where is the 2x2 wire reinforcement placed within the bed cross-section?
A.Directly on the cleavage membrane, before mortar placement
B.Near mid-depth of the bed, raised off the cleavage membrane
C.On top of the finished bed before tile is set
D.It is not used in F112
Explanation: The wire fabric is positioned near mid-depth of the mortar bed so it can resist tensile cracking from below and above. Some installers screed half the bed, lay the wire, and place the upper half over it.
9Which of the following best describes "unbonded" in the context of TCNA F112?
A.Tile is not bonded to the mortar bed
B.The mortar bed is not adhered to the substrate
C.Grout is not bonded to the tile edges
D.The tile is set without a bond coat
Explanation: "Unbonded" refers to the mortar bed not being adhered to the substrate. The cleavage membrane breaks that bond so the bed floats.
10When is TCNA F121 (unbonded bed with waterproof membrane) preferred over F112?
A.Heated radiant floor outdoors
B.Where moisture from above (wet areas) must be contained or substrate may transmit moisture
C.Whenever large-format tile is used
D.Never — F112 and F121 are interchangeable
Explanation: F121 adds a waterproof membrane to the unbonded bed assembly. It is selected when wet conditions above or moisture transmission from the substrate require containment.

About the ACT Mud Floors Exam

The ACT Mortar (Mud) Floors credential certifies a tile installer's ability to design and float a thick mortar bed for floor tile in accordance with TCNA Handbook methods (F112, F121, F122, F125) and ANSI A108.1A/A108.1B. The certification combines a 25-question written exam (84% to pass) with a field test scored by trained third-party evaluators (85% to pass). Candidates must hold a current CTI from CTEF or have completed IUBAC journeyman apprenticeship.

Questions

25 scored questions

Time Limit

Half/full-day field test

Passing Score

84% written + 85% hands-on

Exam Fee

Contact CTEF/IMI (ACT Consortium (CTEF/TCNA/IMI/IUBAC/NTCA/TCAA))

ACT Mud Floors Exam Content Outline

~16%

Floating Mortar Bed Methods

TCNA F112 (unbonded mortar bed on concrete), F121 (with waterproof membrane), F122 (anti-fracture membrane), F125/F125A (crack-isolation membrane), cleavage membrane principle

~16%

Mortar Mix Design

Deck-mud 1:5 cement-to-sand, sharp/concrete sand, water content (compressed-handful), latex-modified admixtures per ANSI A118.4/A108.1B

~16%

Substrate Preparation

4-mil polyethylene cleavage membrane, 2x2 16-gauge WWF or galvanized lath reinforcement, perimeter expansion, ANSI A108 prep tolerances

~14%

Floating Thickness

1-1/4 in minimum to 2 in maximum unbonded mortar bed, slope tolerance for drains

~14%

Screeding & Finishing

Long straight-edge screeding, wood float vs. steel trowel, mortar slick bond coat, surface tolerance 1/4 in / 10 ft

~14%

Slope & Drainage

1/4 in / ft minimum slope to drain, double-slope shower receptor with pre-pan, two-stage drain weep-hole protection

~10%

Movement Joints & Curing

TCNA EJ171 perimeter and field joints, 1/8 in min width, ASTM C920 sealant, 24-72 hr mortar bed cure

How to Pass the ACT Mud Floors Exam

What You Need to Know

  • Passing score: 84% written + 85% hands-on
  • Exam length: 25 questions
  • Time limit: Half/full-day field test
  • Exam fee: Contact CTEF/IMI

Keys to Passing

  • Complete 500+ practice questions
  • Score 80%+ consistently before scheduling
  • Focus on highest-weighted sections
  • Use our AI tutor for tough concepts

ACT Mud Floors Study Tips from Top Performers

1Memorize the unbonded mortar bed thickness: 1-1/4 in minimum to 2 in maximum (TCNA F112/F121)
2Deck mud is 1:5 cement-to-sand by volume — sharp/concrete sand, dry-pack consistency (compressed-handful test)
31/4 in per foot minimum slope from perimeter to drain; double-slope (pre-pan + top bed) for shower receptors per TCNA B415
4Cleavage membrane (4-mil poly or 15-lb felt) plus 2x2 16-gauge WWF reinforcement is the standard unbonded assembly
5TCNA EJ171: 20-25 ft max field joint spacing interior dry, 8-12 ft when exposed to sunlight/moisture, 1/8 in min width, ASTM C920 sealant
6Wood float compacts and levels; steel trowel finishes — overworking with the steel trowel can over-densify the surface and create bond problems

Frequently Asked Questions

What is the ACT Mortar (Mud) Floors credential?

ACT Mortar (Mud) Floors is one of the Advanced Certifications for Tile Installers offered by the ACT Consortium (CTEF, TCNA, IMI, IUBAC, NTCA, TCAA). It certifies that a tile installer can correctly design and float a thick mortar bed for floor tile per TCNA Handbook methods and ANSI specifications. The credential consists of a 25-question written exam (84% to pass) plus a field test scored by trained third-party evaluators (85% to pass).

What is the difference between TCNA F112 and F121?

Both are unbonded (floating) mortar bed methods over a concrete substrate, separated from the slab by a cleavage membrane and reinforced with 2x2 wire mesh. F112 is the basic interior floor method (no topical waterproof membrane). F121 places a waterproof membrane between the cleavage membrane and the slab — used where moisture from above must be contained or where the substrate could contribute moisture. The mortar bed thickness rule (1-1/4 in minimum to 2 in maximum) is the same for both.

What sand and cement ratio is used for deck mud?

ANSI A108.1A specifies one part Portland cement to five parts damp sand by volume (1:5). Sharp "concrete" sand (also called torpedo sand) is preferred over fine masonry sand because it interlocks better. The mix is dry-pack consistency — just enough water that a compressed handful holds together with no visible free water. Some installers use 4:1 for a richer bond but 5:1 is the published standard.

Why use a cleavage membrane under a mortar bed?

A cleavage membrane (typically 4-mil polyethylene or 15-pound roofing felt) breaks the bond between the mortar bed and the substrate, allowing the bed to "float" independently. If the slab cracks or moves, the mortar bed and the tile above it are isolated from that movement. The membrane also prevents the substrate from absorbing water from the fresh mortar, which would weaken the bed.

What slope is required from perimeter to drain?

TCNA specifies 1/4 in per foot (about 2% or 1:48) minimum slope from the perimeter walls to the drain. For shower receptors, the double-slope approach applies: the pre-pan mortar bed beneath the waterproof pan membrane is sloped 1/4 in / ft, and the top mortar bed above the pan is also sloped 1/4 in / ft. The two stages give the waterproof membrane positive slope to the drain weep holes.

How long should a mortar bed cure before tile is set?

The mortar bed typically requires 24 to 72 hours of cure before tile is bonded to it, depending on bed thickness, mortar type, ambient temperature, and humidity. The bed must be hard enough to walk on without indentation, and surface moisture should have dissipated to a saturated-surface-dry condition. Latex-modified beds may need longer dry-back time before bonding because the latex retards surface moisture loss.