External wall insulation in Chambéry.

External wall insulation, or ITE, involves wrapping all the walls of your house in a continuous insulating layer, fixed to the outer face of the façade and then covered with render or cladding. The building is thus protected from both cold and heat from the outside, like a coat pulled on over the existing structure.

The key difference from internal wall insulation (ITI) lies in the principle: external insulation does not encroach on living space. You do not lose a single square metre inside, you do not have to move your furniture and you can stay in your home during the works. Above all, external insulation effectively eliminates thermal bridges — those areas where heat escapes at floors, corners and internal walls — which internal insulation deals with far less well.

In Chambéry's alpine climate, hemmed in between the Bauges massif, the Chartreuse and the Chambéry gap, winters are cold and temperature swings are sharp: this continuous treatment of the building envelope transforms comfort. Walls stay warm, the thermal mass of the building is preserved and heating bills fall for good. It is now one of the most effective and best-subsidised energy renovation solutions for a detached house in Chambéry as well as for small apartment buildings on its outskirts.

There are several ways to install external wall insulation, and the choice depends on the architecture of your façade, the look you want and your budget. The most common technique is rendered EWI: insulating boards (polystyrene, rock wool or wood fibre) are bonded and anchored to the wall, then covered with a mesh-reinforced base coat and a finishing render. The result looks like a conventional rendered façade, in the colour of your choice — a finish particularly well suited to detached houses in La Ravoire, Cognin or Barberaz.

Clad EWI, on the other hand, relies on a frame fixed to the façade, which holds the insulation and then a ventilated facing: timber cladding, composite cladding, metal or mineral materials. This solution provides a very durable ventilated air gap and a wide choice of looks, and blends perfectly with the mountain character of Savoyard houses and the chalets on the slopes of Vimines or Montagnole. Finally, insulated facing systems and ready-to-fit insulating panels allow fast works in certain configurations.

The right choice is made case by case: a very flat, regular façade lends itself well to render; a façade you want to clad in timber, or one that is uneven, will be better served by cladding. We work out the insulation thickness required, the treatment of details (window sills, roof overhangs, downpipes) and the constraints of Chambéry's local plan (PLU) before recommending the most suitable technique.

One of the great advantages of EWI is that it combines naturally with façade refurbishment. If your façade is tired — cracked render, dirt, flaking paint — and refurbishment is needed anyway, it is the ideal time to insulate. Rather than simply freshening up an uninsulated wall, you share the cost of scaffolding and labour to carry out two projects in one. On Chambéry's inner-suburb buildings, where old render often deteriorates in patches, this pooling is particularly cost-effective.

The benefit is twofold: you improve energy performance while giving your house a complete aesthetic makeover. New render colours, contemporary timber cladding, redesigned mouldings: EWI is an opportunity to modernise the look of your property and increase its value. For a small apartment building on the outskirts of Chambéry or a town-centre house, it is also a chance to harmonise the whole façade in line with local regulations.

Atelier NovAlp coordinates the entire operation: survey of the existing building, choice of materials, submission of the prior declaration (déclaration préalable) of works, façade treatment if needed, fitting the insulation and finishing. You have a single point of contact from design through to handover.

Not all of Chambéry is suited to external insulation. The historic centre, with its arcaded streets, the Château des Ducs de Savoie and its façades of stone and old render, lies within a conservation area where the appearance of buildings is strictly controlled. Near protected monuments, the opinion of the ABF heritage architect (Architecte des Bâtiments de France) is mandatory: EWI is often restricted or even refused there, as it would alter the relief and proportions of heritage façades.

In these situations, internal wall insulation (IWI) becomes the relevant alternative. It preserves the listed exterior while significantly improving thermal comfort. Done properly — with careful treatment of thermal bridges at floors and internal load-bearing walls, and management of water vapour — IWI makes it possible to renovate a flat or house in the old town without conflicting with planning rules.

Conversely, as soon as you move away from the historic core — towards the inner suburbs, detached houses and small apartment buildings on the outskirts (La Ravoire, Cognin, Barberaz, La Motte-Servolex, Bassens) — EWI becomes the standard solution again. We systematically analyse your property's location and eligibility before steering you towards EWI or IWI, factoring ABF constraints into the study from the outset.

External wall insulation is one of the best-supported measures under public schemes. As a company certified RGE CertiRénov (no. CR-2026-73-0095), Atelier NovAlp enables you to draw on MaPrimeRénov', Energy Saving Certificates (CEE) and the zero-interest eco-loan to finance your EWI. These grants, which can be combined subject to conditions, greatly reduce the remaining cost and make the work affordable for Chambéry homeowners and co-ownerships alike.

In terms of performance, walls account for up to 25% of heat loss in a poorly insulated house. By treating this surface continuously, EWI delivers immediate heating savings and improves the home's energy rating (DPE) — a decisive advantage whether you sell or let. Summer comfort also improves, as the walls act as a shield against the heat, a real benefit in the increasingly hot summers of the Chambéry gap.

To go further, EWI fits ideally into an overall energy renovation project in Chambéry: combined with loft insulation, new windows and doors and a heat pump, it can achieve spectacular gains. Find out more about our approach and guarantees on our RGE energy renovation page, or describe your needs via our services page.