Large-format tiles and porcelain need a flexible C2 adhesive, ideally polymer-modified; C1 is only suitable for high-absorption ceramics and wall tiles indoors. Large pieces are heavier, absorb little water and undergo micro-movements from temperature and settlement: if the adhesive is not flexible, debonding and cracking follow.
This content is part of the ConstructHUBS digital issues, within our editorial line dedicated to construction systems and materials.
This guide is based on technical information from Maxipega, a manufacturer and distributor of cementitious adhesives in Panama.
You can also read the version published in the October 2025 issue of Construcción en Panamá magazine (in Spanish).
What is cementitious tile adhesive?
It is an adhesive made from cement, resins and additives that fixes coverings such as ceramic, porcelain, marble and natural stone to floors and walls, indoors or outdoors, including wet areas such as bathrooms and kitchens. Its most common classification follows ANSI A118 and UNE-EN 12004, which measure adhesion, flexibility and open time.
Types of tile adhesive
| Type | What it is for | Not recommended for |
|---|---|---|
| C1 (normal adhesion) | Traditional ceramic, terracotta and high-absorption wall tiles indoors | Large format and porcelain |
| C2 (improved adhesion) | Porcelain, low-absorption tiles, marble and stone; floors and walls | — |
| Polymer-modified C2 | Exteriors, high traffic, humidity and temperature changes | — |
There are also additional classifications that indicate specific properties: S1 and S2 (deformability or flexibility), E (extended open time), T (reduced vertical slip) and F (fast setting).
Why does large format need a special adhesive?
Tiles larger than 60×60 cm, or 90×90 cm and above, pose three challenges:
- High weight: they need greater bonding capacity.
- Low absorption: dense porcelain does not absorb water, which makes bonding harder.
- Stress: temperature and settlement cause micro-movements that a rigid adhesive cannot tolerate.
In Panama’s hot, humid climate, a flexible adhesive is essential to prevent debonding.
Common mistakes when installing large tiles
- Using C1 instead of C2.
- Not leveling the substrate, which leaves voids and causes debonding.
- Poor notched-trowel technique that reduces contact with the tile.
- Ignoring movement joints, which can lift tiles.
Best installation practices
- Back-buttering: apply adhesive to both the substrate and the back of the tile.
- The right trowel: for large pieces, a notch of 10 mm or more.
- Spacers and leveling systems: ensure uniformity and prevent lippage.
- Open time: follow the manufacturer’s instructions.
- Substrate preparation: fresh concrete, old slabs, leveling mortars or plastered walls need different preparation.
Which adhesive to choose by use?
In homes the priority is appearance and durability; in commercial and institutional spaces, a high-performance adhesive for heavy traffic. For large format, Maxipega recommends its Maxipega Porcelanato line (flexible C2), which the manufacturer says meets ANSI 118.4 and 118.11 and works indoors and outdoors, on floors and walls.
Frequently asked questions
What is the difference between C1 and C2 adhesive?
C2 has improved adhesion and is suitable for porcelain and large format; C1 is for high-absorption ceramics indoors.
Which trowel should be used for large porcelain tiles?
A notched trowel of 10 mm or more is recommended, together with back-buttering.
Why do tiles come loose?
The most common causes are the wrong adhesive, an unlevel substrate, poor trowel application or missing movement joints.
