Roof terrace tiling in Morocco: 8 mistakes to avoid before the autumn rains
A tiled roof terrace that leaks or blisters almost never blames the tile: it blames the order of the layers, the fall or the joints. Here are the eight mistakes we see most often on sites in Morocco, and the checklist to hand to your tiler before the rains.
Published on by the Amarchy team
Roof terrace tiling in Morocco: where leaks and blisters come from
A roof terrace is the most exposed part of a house: direct afternoon sun, dew at night, wind-blown dust and sand, then rain concentrated into a few weeks. Roof terrace tiling in Morocco therefore endures what no interior floor endures, and it is often in the first autumn that the faults appear: a damp patch on the ceiling of the room below, a tile that sounds hollow underfoot, a blister swelling in the sun.
These problems rarely come from the tile itself. They come from what is underneath and around it: a badly made fall, missing or punctured waterproofing, joints left out, adhesive applied to a damp substrate. Here are the eight most common mistakes, in the order in which they cost the most.
Mistakes 1 to 3: the fall, the waterproofing and the order of the layers
Mistake 1: relying on a flat slab. Water has to reach the outlet on its own. So a fall of around 1 to 2% towards the outlets is formed in mortar or lightweight concrete, before the waterproofing. A level slab with tiles laid on top leaves puddles: dust settles there, moss takes hold, and the water always finds a way in. Also look at the number and position of the outlets: a single outlet in a far corner forces a steep fall and creates a low point in the middle of the terrace.
Mistake 2: believing the tiles are waterproof. On a roof terrace, the tiling is a protection and a finish; the waterproofing is underneath, as a continuous system, with upstands on the walls and parapets and rebates in the door thresholds. The classic mistake is to pierce that system to fix a balustrade, an air-conditioning bracket or an aerial, or to run a duct through without a collar. Every penetration must be planned and reinforced before laying, never afterwards.
Mistake 3: getting the order of the layers wrong. From the bottom up: structure, fall, waterproofing, protection or separation layer, exterior adhesive, tile, joint. Skip the protection layer and you are sticking tiles straight onto the waterproofing: the assembly moves, the adhesive does not grip, and the tiling comes away in sheets after one or two seasons. Trying to make good waterproofing forgotten under tiles already laid means demolishing everything.
Mistakes 4 and 5: movement joints and laying joints
Mistake 4: leaving out movement joints. An outdoor slab moves: it expands in the sun and contracts at night. The tiling has to move with it. Provide regular movement joints in the tiling, perimeter joints at the foot of the upstands, and respect the structural movement joints. Filling them with rigid mortar blocks the movement: the tile lifts or cracks, often directly below a wall corner.
Mistake 5: laying tight-jointed or with joints that are too narrow. Indoors, you can almost butt the tiles together; outdoors, you cannot. Keep clear joints, wider than indoors, to absorb expansion and let the whole assembly breathe. The details — foot of upstands, around outlets, junctions with a wall — are treated with elastic sealant, not with grout. A joint a few millimetres wide at the bottom of the upstand, around the perimeter, stops the terrace pushing against the walls.
Mistakes 6 and 7: the wrong tile and laying on a damp substrate
Mistake 6: choosing the tile for its looks rather than for the climate. An interior floor porcelain, glossy, thin and absorbent, or an untreated porous stone: that is what lasts two summers before staining, cracking or becoming slippery at the first dew. On a roof terrace you need a full-body porcelain, with low water absorption, UV-stable, frost-resistant — which matters in the highland regions — and slip-resistant: R11 is the minimum as soon as there is water or a pool edge nearby. A light tone limits how hot the slab gets and makes the terrace more bearable in summer.
Mistake 7: sticking tiles to a damp substrate or in too much heat. A recent screed, a slab that has taken in water, a floor washed the day before: sticking tiles onto that traps the moisture under the tile. It rises, loosens the adhesive, and the tile comes off at the first thermal shock. Check flatness and moisture, apply a suitable primer, use an improved exterior adhesive with back-buttering. In full heat, avoid sticking tiles to a burning slab, work early in the morning and protect the work from the sun for the first few days.
Mistake 8: forgetting maintenance after the summer
Three months of dust, sand and leaves have filled the outlets and the joints. Before the rains, empty and rinse the outlets, then pour a bucket of water to see where it pools: that is the best diagnosis, free and immediate. Then sweep, wash with water and a neutral soap, without concentrated bleach and without a pressure washer on the joints, which scours and opens them.
Run your hand over the joints: those that are cracked or hollowed out should be redone before the rainy season, otherwise the water gets underneath. Scrape off moss and lichen, check the upstands at the foot of the wall and the door thresholds, and on natural stone, redo the protective treatment if the stone drinks the water. A roof terrace maintained once a year lasts incomparably longer than one that is never looked at.
The checklist to hand to your tiler
Print this list, or send it as it is on WhatsApp. It avoids the most common misunderstandings, and it gives you points to check when you accept the work.
- A fall of 1 to 2% towards the outlets, checked with a straightedge and a level
- Enough outlets, with accessible gullies and clear downpipes
- A continuous waterproofing system, with upstands on the walls and rebates in the thresholds
- No untreated penetrations: balustrades, air-conditioning brackets, aerials, ducts
- A protection or separation layer between the waterproofing and the adhesive
- Movement joints and perimeter joints planned from the tile layout stage
- An exterior porcelain with low absorption, R11 slip resistance, laid with wide joints
- Back-buttering with exterior adhesive, on a dry, clean, primed substrate
- Flexible grouting and elastic sealant at the details
Free quote, single point of contact, guarantee: taking action
Amarchy has been working with tiling and zellige for 12 years in Morocco, with more than 400 projects delivered, and counts among its clients private customers across the country, architects, developers and Moroccans living abroad. Our showroom is in Skhirat, Lot. 34 Jaouhara, open Monday to Saturday from 9am to 7pm: there you see the tiles for real, in the light, and compare ranges to suit your budget. Our sites are in Skhirat, Témara, Rabat, Bouznika, Casablanca and throughout Morocco.
The quote is free and detailed, item by item, so you can decide between what is essential and what can wait. You receive your estimate within 24 hours, you keep a single point of contact from the first call to acceptance, and bespoke work and its laying are covered by a 2-year contractual guarantee, with materials keeping their manufacturer's guarantee.
One call is enough to get started: 05 37 78 70 07, or WhatsApp on 06 61 97 80 99 with the approximate area and two or three photos of your terrace. No pressure, no commitment: first a diagnosis and a clear price.
