Here it is a cooling problem, not a heating problem
Most British owners have met external wall insulation before, and they met it as a heating measure. Solid-wall Victorian terrace, cold bedrooms, government grant, keep the warmth in.
That is not the argument here, and if you approach it that way the numbers will not make sense to you. In North Cyprus the complaint is the opposite. The air conditioning runs from May to October. There is a room upstairs that never really cools down, whatever you set the unit to. The bill in August is the one that makes you look at the meter twice. And the moment the units go off in the evening, the heat comes straight back out of the walls into the rooms.
That is a fabric problem, not an air conditioning problem, and no amount of extra cooling capacity fixes it. You are paying to cool a wall that has spent all day being heated from the outside and is now releasing it inwards. External wall insulation, known locally by its Turkish name mantolama and technically as ETICS, External Thermal Insulation Composite System, is the measure that addresses the wall itself.
The winter benefit is real too, and for a lot of owners it turns out to matter more than they expected, because it is the same measure that deals with the cold internal wall surfaces that produce condensation and black mould. But the reason people call us in the first place is the summer.
Why the walls here get so hot
The surface temperatures are not what you would guess
From June to September air temperatures here sit frequently between 38 and 42°C. That is the number people quote. The number that matters to your wall is the surface temperature, and on a south-facing elevation in direct sun that reaches 60 to 70°C.
That heat does not stop at the render. It crosses the wall through the day and arrives on the inside face in the late afternoon and evening, which is exactly why the hot room is worst at seven in the evening rather than at midday. Your air conditioning is not fighting the outside air temperature, it is fighting a large warm radiant surface inside the room.
Cut that transfer and the effect is direct. A correctly insulated wall holds the indoor temperature 4 to 8°C lower in summer. In practice that shows up as an uninsulated property sitting at 28 to 32°C indoors with the air conditioning running, against 24 to 26°C in the insulated equivalent with the units working less hard.
The heat does not leave when the units go off
The other half of the problem is thermal mass working against you. An uninsulated concrete and block wall stores the day's heat and gives it back overnight. A well-insulated building stays cool 2 to 5 times longer after the air conditioning has been switched off than an uninsulated one. For anyone who does not want to run cooling all night, that difference is the whole point.
Salt is working on the wall as well
On the coastal strip through Kyrenia and around Famagusta, salt-laden air works into concrete and into the steel reinforcement within it and corrodes both. An insulation system puts a protective shell over the outside of the wall, keeping salt and moisture away from the concrete and the reinforcement. On a seafront property that structural argument stands on its own, separately from anything to do with energy.
Insulation is not exterior paint
Ordinary exterior paint is a visual and weather finish. It cannot stop heat crossing a wall. An insulation system adds a physical layer that can. The two work together well and neither replaces the other, so a quotation for "insulating render" that turns out to be a coating with no board behind it is not the same product.
What the system actually is, layer by layer
The most useful thing to understand before you take quotations is that this is a system, not a product. Five layers, applied in order, each dependent on the one beneath it. A fault in any one of them drags down the performance of the whole thing, which is why application quality matters at least as much as the materials on the specification sheet.
The five layers, working outwards from the existing wall
Adhesive mortar
A cement-based adhesive bonds the insulation board to the existing wall. The wall has to be clean, sound and dry first. The adhesive can be applied as a perimeter bead with centre dabs, and it must make contact with at least 40 per cent of the board area. Anything less and the board is hanging on too little bond.
Insulation board
EPS, expanded polystyrene, or mineral wool. This is the layer that determines the thermal performance of the whole system. Boards are laid staggered, like brickwork, so that joints do not line up. Joints in line create a thermal bridge straight through the system.
Mechanical fixings
In addition to the adhesive, the boards are fixed back to the wall with steel dowels with plastic discs. The number and position are calculated from the height of the building and the wind load. This layer is what resists wind uplift and suction, and it is the layer most often reduced to save money.
Reinforcement layer: mesh and base coat
A glass fibre reinforcing mesh is embedded into a polymer-modified base coat applied at roughly 3 to 4 mm. This is what gives the system mechanical strength and resistance to cracking, impact and thermal movement. Mesh overlaps should be at least 10 cm, and corners and edges get a double layer.
Primer and decorative top coat
Primer, then a thin coloured decorative render. This is the weather face of the system and the part you see. In this climate it should be a UV-resistant, water-repellent product. Silicone renders hold up longer here and stay cleaner than acrylic. Light colours absorb less heat.
Skip any one of those five, or apply it badly, and you have shortened the life of the system considerably. The layer that gets cut most often is the third, and the one that gets rushed most often is the fourth.
EPS or mineral wool, and how thick
There are two insulation materials in normal use, and they are not interchangeable in every situation.
EPS, expanded polystyrene, is the most widely used insulation board in the world for this application. Its thermal conductivity, lambda, is 0.035 W/mK, with products on the market across a 0.032 to 0.038 range. Mineral wool sits at 0.038 to 0.041 W/mK, so slightly less thermally efficient board for board. Polyurethane foam is the best performer of the three at 0.022 to 0.035 W/mK. The lower the lambda, the better the material insulates.
EPS and mineral wool compared for use in North Cyprus
| EPS (expanded polystyrene) | Mineral wool | |
|---|---|---|
| Thermal conductivity | 0.035 W/mK, typically 0.032 to 0.038 | 0.038 to 0.041 W/mK |
| Material cost | The cheaper option | Roughly 25 to 40 per cent more expensive |
| Fire | Combustible; needs A2 fire barriers on buildings of five storeys and above | Class A1, non-combustible, resists up to 700°C |
| Water | Does not absorb water, very low moisture permeability | Moisture management is critical, must not be applied wet |
| Vapour | Low permeability, an advantage in some buildings and not in others | Vapour open, lets the structure breathe |
| Sound | Weak acoustically | Excellent acoustic performance |
| Weight and handling | Light, easy to cut, keeps scaffolding and labour costs down | Heavier, more careful handling, more load on the scaffold |
| Availability here | Readily available | Supply in North Cyprus can be more limited |
Which one for your building
For most houses on this island the answer is EPS, and the reasoning is straightforward. On a one to four storey villa or apartment, EPS at 5 to 8 cm gives economical and entirely adequate thermal performance. On the coast, EPS has a specific advantage: it does not take up water, so a build-up without a vapour barrier suits the conditions.
Mineral wool earns its extra cost in defined situations. On buildings of five storeys and above, fire regulations drive the choice, and the options are EPS with fire barriers or a full mineral wool system. Hotels and commercial buildings go the same way for fire safety. Where there is a genuine acoustic problem, a road or a noisy neighbouring use, mineral wool is the material that does something about it and EPS is not.
Where the budget is tight, a 3 to 5 cm EPS build-up is a legitimate cost and performance compromise, but understand that you are buying less than the standard specification, and expect proportionately less.
How thick, and does it matter
Thickness is where most of the quiet cost-cutting happens, because nobody can see it once the render is on.
The minimum worth specifying on a house here is 5 cm, and the normal specification for a one to four storey property is 5 to 8 cm EPS. The energy figures quoted for Cypriot homes, roughly 30 to 40 per cent off the annual energy bill, are based on a standard 5 cm EPS system. If someone offers you 3 cm to bring the price down, they are offering you a system that will not deliver those figures.
There is also a payback calculation that owners here find useful. On a 150 m² apartment, once the investment cost is set against the energy saved, the payback period generally works out at 5 to 8 years. That is before you count the two other effects: an insulated and rendered facade needs repainting every 10 to 15 years rather than every 5 to 7, and there is a 5 to 15 per cent potential uplift in market value on a property that has been done properly.
Before and after, in North Cyprus conditions
| Uninsulated | After external wall insulation | |
|---|---|---|
| Summer indoor temperature | 28 to 32°C with air conditioning running | 24 to 26°C, with the units working less |
| Winter condensation risk | High, particularly on north elevations | Very low to none |
| Annual energy cost | Baseline | 30 to 45 per cent lower |
| Salt and moisture reaching the concrete | Concrete directly exposed | Protected behind the system |
| Repainting interval | Every 5 to 7 years | Every 10 to 15 years |
| Market value | Baseline | 5 to 15 per cent uplift potential |
What it does for condensation and mould
This is the part British owners do not expect, and it is often what turns the decision.
Winters here look mild against Central Europe, but the humidity reaches 70 to 80 per cent. In a property that is unheated, or lightly heated, or shut up for months while the owners are back in the UK, the internal faces of the external walls run cold. Warm moist indoor air touches those cold surfaces and gives up its moisture onto them. Over a season that produces damp walls, black mould and plaster breaking down, and it concentrates on north elevations, in ground-floor flats, and on the concrete columns and beams of the frame, which conduct heat better than the block around them and so sit colder.
External wall insulation removes the cause rather than managing the symptom. By raising the temperature of the internal wall surface it takes away the cold face that the moisture was condensing onto, and it does it across the whole elevation including the concrete frame, which is the part no amount of ventilation or anti-mould paint reaches.
If you are dealing with mould and are not certain whether it is condensation or water coming through the wall from outside, read our guide to damp and mould in North Cyprus homes first. The distinction decides which repair you need, and insulation is only the answer to one of them.
What it will not fix
Being clear about this saves arguments later.
External wall insulation is not the repair for these
- Rain penetrating through a defective facade. Water arriving from outside has to be stopped where it gets in. Boarding over an active leak seals the moisture in behind the system.
- A leaking roof or terrace. A great deal of what looks like a wall problem is water arriving from above and running down the inside of the structure.
- A leaking balcony above. Same story, different source, and a different repair.
- Rising damp from the ground. Ground moisture drawn up into the structure is dealt with at the base of the building, not on the elevation.
- A wet wall. Application onto a wet or damp substrate is a defect in itself, not a cure. The wall has to be dry before anything is bonded to it.
- Structural cracking that is still moving. Cracks are repaired and their cause resolved before the system goes on, otherwise they will come through the new render.
The sequence matters. Waterproofing defects get resolved first, the wall gets time to dry, then the insulation goes on. Our waterproofing work and facade and rendering work are usually planned together for exactly this reason.
When it is worth doing, and when to do it
The clearest cases we see are these: a property with high summer electricity bills and rooms that never come down to temperature; a north-facing elevation or a ground-floor flat with recurring condensation and mould; a facade that is due for repainting anyway, where the scaffolding and preparation cost is being spent regardless; a coastal property where the concrete is being attacked by salt; and any property being refurbished, because doing it as part of a wider renovation programme costs a fraction of coming back for it later.
Timing is a real constraint here rather than a preference.
The ideal ambient temperature range for application is 5 to 30°C. That rules out much of July and August, when the wall surface reaches 60 to 70°C and the adhesive, base coat and render dry so fast they crack. The material has to cure at a controlled rate, and on a south elevation in August it does not. It also rules out the wet months, because the substrate has to be genuinely dry, with 2 to 3 weeks of drying allowed before work begins.
That leaves two windows: March to May and September to November, when temperatures sit at 15 to 28°C, humidity is balanced and the risk of rain is low. Those are the months worth booking. If the work has to happen in high summer, it is done early in the morning and on shaded elevations, following the sun round the building.
The mistakes that ruin the job
Almost every failed insulation system we are called to look at failed for one of six reasons, and all six are the result of saving money or not knowing better.
Applying onto a wet or damp wall. In Cypriot winter conditions, bonding to a damp surface badly weakens both the adhesive and the base coat. It can look perfect on handover and start blistering, delaminating and separating within a few years. The wall should be checked with a moisture meter before anything is applied.
Too few mechanical fixings. Reducing the dowel count per square metre to bring the price down risks sections of the system, or the whole elevation, coming off under wind load. The minimum is 6 per square metre across the field, rising to 9 per square metre at edges and corners. On the Kyrenia coast wind loading is not theoretical, and edge and corner zones need at least 50 per cent more fixings than the field area.
Inadequate mesh overlaps. Where the reinforcing mesh does not lap properly over the board joints, cracks open along the joint lines. The related error is leaving out the diagonal reinforcing patches at 45 degrees at window and door corners, which is where stress concentrates. Those corner cracks are hard to see from inside and grow unnoticed.
Working in the wrong weather. Applying base coat and render in full summer sun, especially on a south elevation, is extremely common and wrong. The material flashes off and produces the fine net of hairline cracking known here as sun cracking. Painting over it afterwards does not close the moisture path.
Boards not staggered. Horizontal or vertical joints left in line create thermal bridges. Boards must be laid in a staggered, brick-bond pattern, and interlocked at external corners.
Skipping the starter track. The aluminium base profile is fixed at the bottom of the system, roughly 30 to 40 cm above ground level, dead level. Some installers leave it out to move faster. The bottom edge of the system is then open, and ground moisture, splash-back and insects get in behind the boards. On buildings near sea level here that is a serious error.
Questions worth asking any contractor quoting for this
- What board thickness are you quoting? (5 cm minimum on a house)
- EPS or mineral wool, and why that one for my building?
- How many mechanical fixings per square metre, and what is the rate at edges and corners?
- What is the mesh weight? (160 g/m² or heavier)
- What overlap on the mesh, and are window corners getting diagonal reinforcement?
- Is a starter profile included at the base?
- Which top coat, silicone or acrylic?
- What is the programme, and how are you handling application in direct sun?
- Is there a separate guarantee on workmanship and on materials?
Judge the quotation by what is in the middle of the system
Anyone can quote a colour and a board thickness. The parts that decide whether the system lasts 25 years or 5 are the fixing rate, the mesh weight and laps, the corner reinforcement and the base profile. If a quotation does not mention them, it is not a specification, it is a price.
Getting it looked at
We have been working on buildings in North Cyprus since 1999, more than 25 years, from Ankara Caddesi No:109 in Alsancak, just outside Kyrenia. We survey free of charge, tell you whether insulation is actually the right measure for what you are experiencing, and put the system, board thickness, fixing rate, finish and price in writing before anything starts. Our work carries a 5-year workmanship guarantee, and everything is handled in English, including while you are back in the UK.
Call +90 533 831 14 32 or email [email protected].
More on our facade and rendering work, or look through recent projects around Kyrenia. If your concern is water rather than heat, our guides to flat roofs leaking in North Cyprus and damp and mould cover the other side of the same building.