Know more about insulation

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Insulation protects the interior of the home from the influence of the exterior, both thermally and acoustically.

As the saying goes, “the best energy is the energy you don’t consume” and insulation makes this possible.

The diversity of the offer

There is a large choice of insulation materials. Whether it is glass wool, cellulose wadding, or wood wool, there will always be a solution for the exterior or interior insulation of the walls and attics of your home. These materials can also be ecological such as for example sheep wool, hemp, or wood wool, which also fall into the category of thermal insulation. Drawing up a comparison of these insulators is a huge undertaking because there is no better insulator: it all depends on your home.

The value of thermal insulation

Insulating the various parts of the home saves energy, and therefore financial savings. Knowing which building materials are conductive and insulating provides an idea of ​​the extent of the work to be carried out. Natural insulation is often not enough to effectively protect a home. Thus, the concrete floor (or slab), the parquet, the pipes, the roof terraces, the garage, and the doors are veritable colanders for heat.

The possibilities

They are numerous in view of the number of insulation materials identified. The price of the exterior insulation is not the same as that of the interior insulation, but it is not necessarily that it turns out to be compulsory to spend the winter in the warm. Attention however, because certain works insulation requires a self-contained breathing apparatus to work safely. This is why it is recommended to contact a professional insulation company.

The different types of insulation installation

Not all insulation is installed in the same way and certain poses are to be avoided depending on the chosen insulation. Consider using a qualified and specialized professional for your insulation work.

The different insulators offered by masseria are:

• Wood wool

• Glass wool

• Rockwool

• Cellulose wadding

• Métis (recycled jeans)

• Liege


The diversity of the offer.

There is a large choice of insulation materials. Whether it is glass wool, cellulose wadding, or insulating plaster, there will always be a solution for exterior or interior insulation of the walls and attics of your home. These materials can also be ecological such as for example sheep wool, hemp, or wood wool, which also fall into the category of thermal insulation. Drawing up a comparison of these insulators is a huge undertaking because there is no better insulator: it all depends on your home. In terms of sound insulation, whether for the ceiling or partitions, there are various effective acoustic foams for the soundproofing of all or part of the home.

The value of thermal insulation

Insulating the various parts of the home saves energy, and therefore financial savings. Knowing which building materials are conductive and insulating provides an idea of ​​the extent of the work to be carried out. Natural insulation is often not enough to effectively protect a home. Thus, the concrete floor (or slab), the parquet, the pipes, the roof terraces, the garage, and the doors are veritable colanders for heat.

The different types of insulation installation

Not all insulation is installed in the same way and certain poses are to be avoided depending on the chosen insulation.

Each house must be studied to choose the most suitable insulation and according to your budget.

The losses in your non-isolated accommodation

The losses in your non-isolated accommodation

If in new construction, it is all the walls of the house that must be isolated, in renovation, it is not always possible to completely review the quality of the building envelope. The insulation work is then done in zones (roofs, walls …) and can be spread over several years. What are the priority targets?

 You need to identify the walls of your home that cause the most energy loss. This table can help you find out the average losses of a non-isolated dwelling.

So we can see that the insulation of the attic is a priority. If on these general principles, we can consider that the thermal insulation of doors and windows comes after that of the floors, in practice, it is easier to modify the doors and windows during the thermal insulation of the walls, second loss position in a little or not isolated habitat. In addition, according to the construction method applied, insulating the floors is more difficult to achieve (eg construction in plain earth with little height available under doors and French doors, construction on crawl space not accessible, etc.).

In general,

New: choosing a high performance insulation is to make sure to minimize the need for heating and cooling consumption and therefore also limit the energy bill without compromising on comfort!

In renovation: act on the association “wall insulation and mechanical ventilation + windows and blackouts”, it is to at least halve the energy consumption and therefore by two the amount of the invoice. This first phase is already making it possible to reduce most of the heat loss and therefore energy consumption with good comfort.

Other solutions for diagnosing your insulation are available to you for a personalized and more precise evaluation.

To give you an example:

diagnosing your insulation


Benefits of thermal insulation – Thermal insulation in summer and winter.

The comfort in a home depends on maintaining the desired interior temperature whatever the season. The conditions for success in winter and summer comfort are: insulation with very high thermal resistance of all the walls (including the windows) + ventilation adapted to the season + external blackouts + thermal inertia of the building.

What is winter comfort?

A temperature difference of a few degrees between the atmosphere and the walls or between the feet and the head makes one shiver. It’s the feeling of discomfort. This feeling of embarrassment appears as soon as the temperature difference is 3 ° C higher between the temperature of the rooms and that of the walls (window, floor or wall). This is called the “cold wall” effect which disappears as soon as the walls are isolated.

Isolating thus lowers the level of the room temperature. Only a detached house can heat to 19 ° C with real thermal comfort. Be aware that heating by 1 ° C more does not necessarily bring more comfort but increases energy consumption by 5%. In addition, insulating walls, ventilating and moderately heating helps maintain a healthy lifestyle and ensures the conservation of the building.

What is summer comfort?

In the past, window sizes were limited to prevent heat loss in winter. Today the windows are larger because they are more efficient and equipped with efficient shutters. When the windows are facing south, they save more energy than they lose heat in winter. In addition, they reduce the amount of artificial lighting.

However, to limit overheating in summer, the glass surfaces must not exceed 20 to 25% of the living area. Beyond that, warming up through the windows causes discomfort.

The conditions for successful summer comfort

The optimization of summer comfort must be planned from the design of the house and depends on several factors:

Summer comfort = high thermal resistance of the walls (this parameter has an influence of 2 to 4 ° C)

+ well oriented and protected glass surfaces (influence of 2 to 4 ° C)

+ night ventilation of the house to dissipate the heat (influence from 2 to 5 ° C)

+ good inertia of the building – ex: heavy floor to limit the rise in temperature of the building (influence from 1 to 3 ° C).

To know :

the use of household appliances (computer, audiovisual) contributes 5 ° C, which is why ventilation is very important.

The number of consecutive days of high heat (beyond 5) can also have an influence of 3 ° C.

Find out more about summer comfort


Do I need a vapor barrier for insulation?

The vapor barrier prevents the flow and stagnation of water vapor in the walls of the building. It thus avoids the risks of condensation and eventually disorder. Its permeance is expressed by its coefficient Sd (in meters): the higher the Sd value, the less the product lets water vapor through.

Vapor barrier: definition

The vapor barrier is a sheet or membrane which, depending on its permeance, reduces or prevents the transfer of water vapor in the walls. Always installed on the heated side of the wall, between the insulation and the finish, it limits the risk of condensation in the walls, a source of discomfort and ultimately pathologies harmful to both occupants and the building (mold, wood rot). Implemented using dedicated parts (adhesives, eyelets, tablets, etc.), an independent vapor barrier membrane can also provide the airtightness function today required by the 2012 Thermal Regulations for all new buildings.

Fitted vapor barrier

In traditional roofing of small interlocking elements such as tiles, slates or shingles, the DTU Roofing (series 40) requires the implementation of a vapor barrier on the underside of the insulation.

To be effective, it must be independent and continuous over the entire wall. If it is crossed by electrical or ventilation ducts, these must be sealed around their edges using a suitable and durable adhesive to ensure the continuity of the vapor barrier.

In new attic spaces or in complete refurbishment, the installation of an HPV (High Permeability to Water Vapor) under-roof screen is required by CPT No. 3560. An independent and continuous vapor barrier on all the walls of the attic must complete the insulation on the heated side of the walls. Implemented using dedicated parts (sealants, durable adhesives, eyelets or airtightness pads), it also provides airtightness today required by thermal regulations. When renovating the roof insulation, the airtightness must also be ensured by an independent membrane, placed on the heated side of the walls.

This membrane can therefore be an independent vapor barrier, placed continuously below the insulation and with Sd greater than or equal to 18 meters or any vapor barrier under Technical Advice or Technical Application Document validating its use for building application.

The Sd value of the vapor barrier also varies depending on the location of the dwelling (whether or not it is well located in a very cold area / mountain climate).

In MOB homes, DTU 31.2 requires that an independent and continuous vapor barrier be placed over the entire envelope of the heated dwelling or building. The vapor barrier must protect the insulation and the structure from water vapor transfers.

It is essential :

on floor

on crawlspace,

on the vertical walls,

on the crawling roofs,

in the ceiling under the roof,

between a room permanently heated and a room not heated or heated intermittently.

The Sd value of this vapor barrier depends on the type of exterior cladding structure as well as on climatic conditions (plain climate or mountain climate). In lowland climate, when an air ventilated on the outside exists behind the exterior covering, we will opt for an interior flexible vapor barrier with a minimum Sd value of 18 m (permeance less than or equal to 0.005 g / m2 .h.mmHg) or any vapor barrier under Technical Approval validated for use in MOB. In the absence of an air gap at the rear of the external covering (for example an insulating lining made of synthetic material covered by a Technical Assessment for implementation), the Sd value of the vapor barrier can go beyond 90 meters.

 The permeance of the vapor barrier will depend on the hygrothermal study previously carried out, taking into account the climatic conditions, the heating and ventilation equipment of the accommodation.

Please note: there are membranes validated by Avis Technique or DTA ( which perform the dual function of air tightness membrane and hygro-regulating vapor barrier.

How to choose a vapor barrier?

The Sd coefficient (in meters) of a vapor barrier expresses the thickness of a layer of equivalent air vapor diffusion air. It represents the resistance to diffusion of water vapor from the vapor barrier:

the higher the Sd value, the less water vapor passes through the product. It is resistant to the diffusion of water vapor.

the lower the Sd value, the more water vapor passes through the product. It is permeable to its diffusion.

Vapor barrier: namely

The vapor barrier must imperatively be independent and continuous, placed on the entire surface of the walls, heated side. It must be perfectly rimmed and sealed with suitable elements ensuring its continuity. Since the water molecule is thinner than that of air (association of molecules), a vapor barrier can also perform the function of an airtightness membrane.

It will also be necessary to ensure the continuity of the vapor barrier on the points of junction of the walls and at the level of the edges of ducts using dedicated accessories such as:

sealants at the periphery

eyelets for the passage of electrical conduits

assessed, compatible and durable adhesives.


In France, millions of homes built before 1975 are still poorly insulated. Their residents are seeing their heating bills soar while this enormous energy waste causes the emission of millions of tonnes of CO2 which contribute to the greenhouse effect.

The public authorities are therefore committed to improving the energy performance of the existing building stock, which consumes 40% of energy in France.

RT in existing buildings meets several requirements:

To comply with European Directives and, in particular, the Energy Performance of Buildings Directive, in the same way as other European countries.

Control energy costs since existing buildings are more numerous and more energy-consuming than new buildings.

Who is concerned by RT in the existing?

The Thermal Regulations for Existing Buildings relate to the entire existing building stock excluding buildings located in the French overseas departments and certain specific buildings listed below.

These regulations impose minimum thermal performance requirements for equipment installed or replaced in an existing building and apply:

to the overall building envelope,

heating systems,

DHW (domestic hot water) and cooling systems,

ventilation and lighting systems (except individual housing),

energy production equipment using a renewable energy source.

Certain specific cases of existing constructions are not affected by RT 2005: buildings not using energy to regulate the temperature, temporary buildings (less than 2 years), those with an area of ​​less than 50m2, those with use of worship or classified historic monuments as well as agricultural or industrial buildings.

Obligations in the existing.

Since November 1, 2007, the thermal regulation by element requires that when insulation work is carried out in existing buildings (installation or replacement), it corresponds to a minimum level of thermal performance. Regarding the walls, the requirements for thermal resistance R are given in this table:

  R value to benefit from the R value tax credit of the regulations by element

Lost roof space R ≥ 7.0 R ≥ 4.5

Converted roof spaces R ≥ 6.0 R ≥ 4.0

Walls R ≥ 3.7 R ≥ 2.3 **

Floors R ≥ 3.0 R ≥ 2.3 ***

Roof terrace R ≥ 4.5 R ≥ 2.5

** this value depends on the type of wall

*** this value depends on the type of floor

Minimum requirements set by the decree of May 3, 2007 relating to the thermal characteristics and energy performance of existing buildings, published in the Official Journal on May 17, 2007,

RT Existing global

Unlike the thermal regulation by elements, the global thermal regulation applies to major renovations of existing buildings (residential and tertiary). These buildings must simultaneously meet the following conditions:

 their completion date is after January 1, 1948

their net surface area is greater than 1000m² (SHON> 1000m²)

the cost of the planned thermal renovation is greater than 25% of the building’s non-land value.

The “global” RT defines an overall performance objective for the building after renovation. The building will be the subject of an energy supply feasibility study prior to the filing of the building permit.

For non-residential buildings, the thermal renovation undertaken must bring a gain of 30% compared to the energy consumption before the works.

For housing, this regulation introduces a limit value for energy consumption after renovation for heating, cooling and DHW (domestic hot water) depending on the heating system chosen and the climate (maximum energy consumption between 80 165kWh / m².year as appropriate). Finally, in order to limit the use of air conditioning in summer while guaranteeing the comfort of the occupants, summer comfort will have to be ensured thanks to a TIC (conventional interior temperature) lower than a reference temperature.

Finally, when components such as insulation, the heating system or the ventilation system, etc. are modified during renovation works, they must meet minimum performance.

These provisions are applicable to works for which the date of filing a building permit (or failing this the date of acceptance of the estimates of works or the award of contracts) is after March 31, 2008.

To find out more:

Reference texts:

Order of December 20, 2007 relating to the construction cost taken into account to determine the non-property value of the building:

Order of June 13, 2008 relating to the energy performance of existing buildings with a surface area greater than 1000 m² when they are the subject of major renovation works

Additional devices

The 2005 finance law introduced a tax credit dedicated to sustainable development and energy savings. Whether you own or rent, this tax system allows you to deduct from your income tax part of the expenses incurred for certain energy improvement works in your main home. This work must be carried out by a professional. The equipment or materials supplied and installed by this professional will be the subject of an invoice which will be valid. The tax credit is calculated on the price of materials and equipment excluding labor (except for thermal insulation materials for opaque walls). New provisions have been applicable since January 1, 2012.

Additional article: Tax credits for insulation – Article 200 quater of the CGI and Article 18 bis of the CGI

5) RT 2012

In order to meet the objectives of saving energy and preserving the environment from the Grenelle Environment Forum, any new building or new part of an existing building must meet the requirements of the RT 2012 label based on low consumption of energy (BBC RT 2012): energy efficient and energy efficient.

RT 2012 concerns all types of new buildings / constructions or new parts of buildings heated to + 12 ° C or cooled to guarantee the comfort of the occupants, with the exception of industrial processes, swimming pools, skating rinks, livestock buildings or buildings located in the overseas departments.

3 performance requirements

These 3 requirements constitute the basis of this new thermal regulation: the limitation of energy consumption (Cepmax), the bioclimatic requirement (Bbiomax) and a reference interior temperature (Ticref) to ensure summer comfort:

Cepmax or maximum energy consumption

represents the building’s capacity to limit its energy needs and push houses to become ecological. It applies to 5 positions: heating, cooling, DHW (domestic hot water), lighting, auxiliaries (heating, cooling, DHW and ventilation).

The conventional energy consumption

The conventional energy consumption of the building for these substations must be less than or equal to a maximum consumption of 50 kWhep / m².year on average. This obligation of maximum primary energy consumption can be adjusted according to the type of building, geographic location, altitude, average surface area of ​​the accommodation, and according to greenhouse gas emissions and heat losses from the energies used, but the more energy efficient your building, the better.

Bbiomax or maximum bioclimatic need

represents the ability to design an efficient and comfortable project regardless of the equipment used. Without dimension and expressed in number of points (average Bbiomax = 60 *), it is defined by type of occupation according to the CE1 or CE2 category (depending on its need for air conditioning) of the building and can be adjusted according to the geographical location, the altitude , the average area of ​​the habitat. It defines a requirement for energy efficiency of the building and therefore a limitation of the energy requirement for the 3 heating, cooling and artificial lighting stations. It promotes strong thermal performance of the building envelope (strong thermal insulation), a bioclimatic design (solar gain, natural lighting). The Bbiomax reflects the impact of the building design, encourages its optimization regardless of the energy systems used in order to have efficient insulation.

For each construction project, a thermal study indicating that the Bbio of the project is less than or equal to the Bbiomax is required upon the filing of the building permit.

the Ticréf represents the reference interior temperature not to be exceeded to guarantee summer comfort: Tic = Ticréf. It is calculated using conventional climate data for each climate zone. Eight climatic zones are defined (H1a, H1b, H1c, H2a, H2b, H2c, H2d and H3) as well as 3 classes of exposure to noise from transport infrastructure (BR1, BR2, BR3).

RT 2012 climate zones

Some additional resource requirements:

the overall treatment of thermal bridges (the more the building envelope is insulated, the more the untreated thermal bridges are penalizing for the overall energy performance result of the building and for your energy bill).

air permeability of housing limited to 0.6 m3 / (m².h) in individual houses and 1m3 / (m².h) in collective housing;

DHW (domestic hot water) production from a renewable energy source (EnR) in individual houses;

a consumption count: the building includes equipment enabling the energy consumption of each dwelling to be measured or estimated, except for consumption by individual wood systems (in detached or attached houses). This equipment makes it possible to inform the occupant monthly for educational purposes and to carry out an energy balance – the measures are indicated by type of consumption: heating, cooling, DHW production, network of electrical outlets and others (lighting, ventilation etc.). )

a total surface area of ​​the bay windows greater than or equal to 1/6 of the living area in order to favor natural light as much as possible, equipped with mobile solar protection, with a requirement on the solar factor (Fs) and a minimum opening surface obligation .

What are the conversion factors from final energy to primary energy?

2.58 for electricity consumption and production

1 for other consumption (gas, wood, fuel, etc.)

Miscellaneous :

When a building (or part of a building) intended for housing is delivered without heating equipment, it must comply with the means requirements and the requirement on the Bbio.

RT 2012 applies to additions or elevations of existing buildings. However, if the addition of surface or the elevation is less than 150m2 and 30% of the surface of existing premises, it is only subject to the requirements of RT Existing or RT element by element.

Who must demonstrate compliance with regulatory requirements?

The client must be able to provide the standardized summary of the building’s thermal study, a thermal study which he will obtain from his prime contractor or architect if he uses their service for his construction project.

This summary must be made available, over a period of 5 years after the declaration of completion of work, for:

Any buyer

Anyone responsible for certifying the building’s compliance with thermal regulations and / or the high energy performance label

Anyone responsible for establishing the DPE (Energy Performance Diagnosis)

Any sworn controller of the application of building rules

  What is the timetable for applying RT 2012?

The 2012 Thermal Regulations apply to all building permits filed on or after January 1, 2013. It is extended to all new buildings or new parts of the building *.

Find out more:

Follow the latest thermal regulations

Discover RT 2012 solutions on

* the following buildings are not affected by the application of RT 2012:

temporary constructions planned for a period of use of less than two years;

buildings and parts of buildings whose normal temperature of use is less than or equal to 12 ° C;

buildings or parts of buildings intended to remain open to the outside in normal operation;

buildings or parts of buildings which, due to specific constraints linked to their use, must guarantee special conditions of temperature, humidity or air quality and therefore requiring special rules;

buildings or parts of buildings heated or cooled for use dedicated to an industrial process;

agricultural or livestock buildings;

buildings located in the overseas departments.