Cyprus's National Building Renovation Plan for 2026–2031 targets thousands of deep renovations every year. But the plan assumes, by default, that façades and roofs can be insulated from the outside. In practice, for a large share of Cyprus's housing stock — apartments in multi-owner buildings and some older villas — that's simply not the case.
Organisational. A building's façade and roof are, as a rule, jointly owned by all apartment owners — not by one person. External insulation isn't one owner's decision; it's a collective decision by all the neighbours. In practice, getting that agreement is hard: someone lives abroad and doesn't respond, someone objects to any work on the façade, someone just doesn't want to bother with meetings. Even if you're willing to pay for insulating your own apartment in full, you can't do it without your neighbours' consent.
Technical. For a top-floor apartment, the problem is different. Insulating the roof from outside requires access to the roof itself — which is usually occupied: water tanks, solar water heaters, AC units, antennas. Add to that an old slab that was never designed to carry the extra weight of roof insulation. And one more common case in Cyprus: an expensive architectural finish (polished concrete, natural stone) that nobody wants to cover up with exterior insulation.
Either way, the conclusion is the same: insulation is only possible from the inside.
Picture a cold glass of water on a hot day — droplets form on it almost instantly. That happens wherever a cold surface meets warm, humid air. The same thing happens inside a wall.
When insulation is external, that "meeting point" of cold and warm stays outside the wall — no problem, moisture evaporates outdoors. When insulation is internal, that point shifts inward, right to the boundary between the old wall and the new insulation layer. That's exactly where moisture accumulates if the material can't move it away — invisibly, under the finish, where the problem only shows up as a smell or stains, once it's already too late.
And this isn't seasonal — it works both ways year-round: in summer, air conditioning keeps cold air inside against heat outside; in winter, heating keeps warm air inside against cold, damp air outside. The risk of condensation inside a wall is a year-round issue, not a summer one.
Mineral wool can't do this job. It insulates well, but it can't move moisture away — it can only absorb it. Once wet on the inside, it loses nearly all its insulating properties, starts to sag and slump under its own weight, and develops a musty smell. A permanently damp, warm layer inside a wall is also an attractive place for cockroaches, ants and rodents to move in.
EPS foam solves the problem a different way — and just as badly: it barely lets vapour through at all, so moisture simply pools at its boundary with the wall, with no way out.
MULTIPOR works differently. It doesn't just let vapour pass through — it can absorb moisture like a sponge, distribute it within itself, and release it back into room air once conditions dry out. According to the manufacturer's data, MULTIPOR lets vapour through roughly 50 times better than XPS and 10–12 times better than standard EPS. That's why, in Europe, where internal insulation has been used for decades — for example, on listed buildings whose façades cannot legally be changed — MULTIPOR remains one of the few materials originally designed for this exact application, rather than merely adapted to it.
With internal insulation, you're literally giving up floor space to the insulation layer — which makes it especially important that the layer lasts the life of the building rather than needing replacement. MULTIPOR is a mineral board in fire class A1: it doesn't burn and doesn't support combustion, withstands direct fire exposure for 12 hours or more, and releases no toxic smoke (and it's smoke, not flame, that causes most fire deaths). The material is certified to the natureplus standard — one of Europe's strictest ecolabels, confirming the absence of harmful substances in its composition. Xella has been manufacturing MULTIPOR for more than 25 years and has insulated millions of square metres of walls and ceilings across Europe. Non-combustible, environmentally certified materials are exactly what tends to get chosen for buildings with elevated safety requirements — museums, libraries, and other buildings holding valuable collections, where fire resistance and material purity both matter enormously.
A corner apartment with two external walls. The outer side is shared façade — it can't be changed without the neighbours' consent. Walls are cold in winter, hot in summer; dark stains appear near the skirting board in the corner bedroom. Solution: insulate the external walls from inside with MULTIPOR boards (5–8 cm typically makes a noticeable difference without eating into the room).
An older building where the slab wasn't designed for the weight of a roof insulation buildup, and the roof itself is occupied by tanks and equipment. In summer the ceiling is hot to the touch; in winter, condensation appears in the corners. Solution: insulate the ceiling from the inside — the load on the slab barely increases, unlike with external roof insulation.
If you can't get your neighbours' agreement for external insulation, that's not a dead end — it's a signal to change approach. Insulating inside your own apartment is, as a rule, work within your own private property: no owners' meeting required, virtually no change to the building's structural load, and a timeline that depends only on you.