In building materials, the difference between work that lasts and work redone within a year is rarely the price of the bag. The most expensive mistake is the right material in a place it does not suit.

First: know the four families

Almost all finishing materials fall into four groups, each with one decisive question:

  1. Adhesives — which tile, and where? Interior ceramic is one case, low-absorption porcelain another, a permanently submerged pool a third.
  2. Preparation (primers) — is the substrate absorbent or smooth? An absorbent surface pulls water out of the mortar and weakens it; a smooth one gives mortar nothing to grip. Each needs a completely different primer.
  3. Insulation — water or heat? Waterproofing stops moisture; thermal insulation reduces heat transfer. Neither substitutes for the other.
  4. Levelling and repair — is the problem flatness or the soundness of the concrete? A levelling compound fixes only the first.

Second: estimate before you buy

Consumption is printed on every datasheet, usually as kg/m². The working rule:

Quantity = area (m²) × consumption (kg/m²) ÷ bag weight

Three factors push the real figure up:

  • Tile size — larger formats need a bigger notch and a thicker bed, so consumption rises.
  • Substrate flatness — an uneven surface swallows extra material. Where the deviation is large, levelling is cheaper than compensating with adhesive.
  • Waste — add 5–10%. Running out mid-job means a cold joint, and that is a permanent weak point.

Third: six recurring mistakes

  1. Adding water to make the mix easier. Extra water raises workability and lowers strength at the same time. The ratio on the bag is not a suggestion.
  2. Ignoring open time. Adhesive that has skinned over will not bond however hard you press. The test is simple: touch it — if it does not stick to your finger, the window has closed.
  3. Dabbing the corners only. Blobs of adhesive leave voids that collect moisture and crack under load. Coverage should be near full, and double-buttered for pools and exteriors.
  4. Mixing in direct sun. Heat accelerates set and can halve the working time.
  5. Tiling over waterproofing that has not cured. Membranes need their curing time before being covered; rushing it traps moisture underneath.
  6. Mixing large batches at once. Mix only what you can use within the stated working time.

Fourth: how to read a datasheet

Look for four numbers before buying: consumption (to size the order), working time (how long you have), layer thickness (does it suit your case), and scope of use (interior / exterior / submerged). If a supplier cannot give you these, you are buying a promise, not a material.

In short

The most expensive material is not always the most suitable, and the cheapest is rarely the best value once rework is counted. Read the datasheet, calculate the quantity, and respect the water ratio — those three alone prevent most of what we see go wrong.

Browse the catalogue to compare specifications and consumption, or start from your governorate for the expected delivery window.