CIDQ IDFX Exam - Topic 3 Question 9 Discussion

Actual exam question for CIDQ's IDFX exam

Question #: 9
Topic #: 3

[All IDFX Questions]

Which thick-set method would produce the BEST bond for installing tile on an uneven subfloor?

AAdditional grout

BAn extra thick layer of adhesive

CA mesh substrate with membrane backing

DWire mesh reinforcement of the mortar bed

Show Suggested Answer

Suggested Answer: D

Installing tile on an uneven subfloor requires a method that ensures a strong bond and a level surface. The thick-set method involves using a mortar bed to create a stable base for the tile. Wire mesh reinforcement of the mortar bed (Option D) is the best method because the wire mesh strengthens the mortar, helping it adhere to the uneven subfloor and providing a durable, level surface for the tile. This method is commonly used in commercial and high-traffic areas for its reliability. Option A (additional grout) is incorrect, as grout fills joints between tiles, not the subfloor bond. Option B (extra thick layer of adhesive) can lead to uneven drying and cracking. Option C (mesh substrate with membrane backing) is more for waterproofing or crack isolation, not for leveling an uneven subfloor.

Verified Answer from Official Source:

The correct answer is verified using NCIDQ IDFX content on material installation methods.

Exact Extract: The NCIDQ IDFX Reference Manual states, ''For uneven subfloors, the thick-set method with wire mesh reinforcement of the mortar bed provides the best bond and stability for tile installation.''

Objectives:

Specify appropriate installation methods for flooring (IDFX Objective: Material Selection and Specification).

Understand construction techniques for uneven surfaces (IDFX Objective: Building Systems and Technology).

NCIDQ IDFX Reference Manual (Section on Materials and Finishes).

Tile Council of North America (TCNA) Handbook (Thick-Set Installation Methods).

by Bea at Jul 11, 2025, 10:21 AM

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Luz

2 months ago

I’ve heard wire mesh reinforcement works wonders too!

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Van

2 months ago

Wait, isn't a mesh substrate better for uneven floors?

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Merlyn

2 months ago

I think an extra thick layer of adhesive is the way to go!

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Gregoria

3 months ago

Definitely agree with that! More adhesive = better bond.

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Helene

3 months ago

Really? I thought additional grout was the best option.

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Robt

3 months ago

I’m leaning towards the mesh substrate with membrane backing, but I’m not confident if it’s the best for bonding on uneven subfloors.

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Miles

3 months ago

I feel like wire mesh reinforcement could be a solid choice, but I wonder if it might complicate the installation process.

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Paola

4 months ago

I remember practicing a question about mesh substrates, and I think they provide good support, but I can't recall if they were specifically for uneven floors.

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Mitzie

4 months ago

I think an extra thick layer of adhesive might help with uneven surfaces, but I'm not entirely sure if it's the best option.

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Corrinne

4 months ago

Wire mesh reinforcement of the mortar bed seems like it would provide a really solid foundation. That's probably the way I'd go.

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Gregg

4 months ago

I'm a bit unsure on this one. I'll need to review the differences between the methods to decide which one would be the most effective.

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Artie

4 months ago

A mesh substrate with membrane backing sounds like the most comprehensive solution to me. That should give a stable, even surface to work with.

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Maddie

5 months ago

I'm pretty sure the extra thick layer of adhesive would be the best option here. That should help level out the unevenness and provide a strong bond for the tiles.

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Felix

5 months ago

Hmm, this seems like a tricky one. I'll need to think carefully about the different methods and how they might handle an uneven subfloor.

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Mollie

7 months ago

I think B) An extra thick layer of adhesive might be easier to apply on an uneven subfloor.

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Iola

7 months ago

I'm feeling saucy, so I'm gonna have to go with A. Additional grout? More like additional fun! Tile installation just got a whole lot spicier.

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Lashaunda

5 months ago

I think B would be the best option for a strong bond.

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Iraida

7 months ago

D all the way, baby! Wire mesh reinforcement is where it's at. Gotta get that mortar bed locked and loaded for maximum stability.

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Luis

5 months ago

I think an extra thick layer of adhesive would work better for me.

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Earleen

6 months ago

I agree, wire mesh reinforcement is definitely the way to go for a strong bond.

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Adolph

7 months ago

I'm not sure, but I think C) A mesh substrate with membrane backing could also work well.

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Irving

7 months ago

I agree with Dortha, wire mesh reinforcement provides added strength for uneven subfloors.

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Dortha

7 months ago

I think D) Wire mesh reinforcement of the mortar bed would be the best option.

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Tamie

7 months ago

B is the obvious choice here. An extra thick layer of adhesive? Sign me up! Thick as a brick, that's how I like my tile installations.

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Glendora

7 months ago

I think C is the way to go. That mesh substrate with membrane backing will really help even out that uneven subfloor. Gotta love some extra support, am I right?

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Elvera

5 months ago

Yeah, that mesh substrate with membrane backing sounds like it would provide the stability needed for an uneven subfloor.

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Dean

7 months ago

I agree, C seems like the most reliable option for ensuring a strong bond.

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