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When soil insulation has not been planned since construction, the solution is to lay insulation on the raw floor. The implementation is simple thanks to panels covered with a floating screed.

Insulating panels on the ground

Difficulty: 3/4
Cost: 357 € / m2
Time: About 5 weeks
Equipment: meter levels
laser and bubble, false-square,
mallet, rubber mallet,
shovel, wheelbarrow, trowel, comb
notched, shears, handsaw,
concrete mixer, water cutter,
grinder, boucharde...

As is the case of many old houses, the floor of this kitchen of 40 m2 was covered with stones directly on the platform. The coating has deteriorated over time and moisture is rising through the joints that were no longer waterproof. It was time to renovate the floor with insulation to improve thermal comfort and reduce the heating bill. It should be remembered that the thermal losses of a poorly or poorly insulated house essentially pass through the ground (between 7 and 10%), the roof (30%) and the walls (25%). The construction took place in two stages. It was first necessary to deposit the old stone cladding with a jack hammer then to disburse the soil on about twenty centimeters. A bed of gravel 10 cm thick was then spread over the entire surface of the room.

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Pouring the screed

A base consisting of a welded mesh (ST25) and a 10 cm thick concrete slab was poured to obtain a stable and flat surface for the installation of the insulation. Soil disbursement was calculated based on the current threshold of the kitchen door, taking into account the thickness of the different materials: slab, insulation, screed and flooring. During the few weeks of drying, the power supplies of the room were drawn from the board. The laying of the insulation and the mineral coating could begin then.

Total coverage for optimal performance

The choice of insulation was based on rigid panels made of polyurethane foam (Knauf Thane 24, thickness 60 mm), easy to fit thanks to their edges equipped with rabbets and tongues. With 62 mm thick, these panels have a very good thermal resistance (2.80 m2.K / W). The size of the panels (1 x 1.2 m) also made it possible to quickly cover the entire surface. As they are easily cut, it is possible to cut slightly on the underside to integrate the electrical ducts. This trick has saved time on the site as it was possible to get rid of the normally required step of the ravoirage (walnut sheaths in a thin mortar screed a few millimeters thick).

1 INSTALLATION OF INSULATING PANELS

1 INSTALLATION OF INSULATING PANELS

Before installing the insulation boards, carefully sweep and vacuum the slab. Place the first panel on the floor without any method of attachment. The grid film seals the insulating foam.

Insulating panels on the ground: ground

If necessary, cut the panels with a handsaw for unhooked masonry or joinery.

Insulating panels on the ground: ground

To continue, fit the panels crossing the joints. As they are grooved and grooved, their implementation is done quickly.

Insulating panels on the ground: floor

The passage of electrical ducts on the ground requires reservations in the insulation. A simple cutter cutter on the underside of the panel is enough.

Insulating panels on the ground: insulating

Under the hearth, a seat is masonry refractory bricks. Under the effect of heat, the panels could become deformed.

Insulating panels on the ground: ground

At the edge of the wall, the floor insulation is completed with the help of properly cut panel drops and placed close to the masonry to avoid any risk of thermal bridging.

2 REALIZATION OF THE FLOATING CHAPE

2 REALIZATION OF THE FLOATING CHAPE

Place a decoupling strip all around the room. The surplus will be cut with the cutter, after drying and before laying the coating.

Insulating panels on the ground: floor

To arm the screed, lay on the insulation welded and ligated mesh between them. Each lattice has been cut to fit the mesh to the geometry of the piece.

Insulating panels on the ground: insulation

Deposit mortar pads at regular intervals, making sure that the mesh is well embedded in the concrete. Adjust the height of the studs with a laser level and a wooden peg.

Insulating panels on the ground: insulation

Place a bed of mortar between two holds. Raise the welded mesh lightly so that the reinforcement is embedded in the screed. The mortar filling begins with a shovel and is roughly smoothed with a trowel.

Insulating panels on the ground: ground

Smooth the screed using a large mason's ruler, the wooden cleats serving as a guide. This smoothing aid also serves to delimit the final height of the screed.

3 INSTALLATION OF FINISH COATING

3 INSTALLATION OF FINISH COATING

Determine a main laying axis, wedged with a large ruler. With a notched comb, spread the mortar glue on the floor.

Insulating panels on the ground: panels

As a double sizing is needed here, coat the underface and then scrape the glue to the notched comb before placing the item on the glued floor.

Insulating panels on the ground: ground

The flooring is a 2 cm thick stone purchased in three widths. The layout was made following an English pose with offset joint to give this kitchen its traditional look.

Insulating panels on the ground: insulation

Adjust the stones with the rubber mallet, ideal tool to ensure a good adhesion of the stone and to avoid any breakage or marking.

Insulating panels on the ground: panels

During installation, check the levels regularly. A simple bubble level overlapping several rows allows you to control and, if necessary, correct the level before the glue dries.

Insulating panels on the ground: ground

In places, the double sizing causes the glue to overflow. Immediately remove the excess with a damp sponge to avoid any mortar after drying.

Insulating panels on the ground: insulation

To make cuts around interior door frames, a template is often necessary. There are specific equipment for this. But failing that, a falling cardboard and a cutter will do the job to postpone a precise route before cutting to the water cutter.

4 JOINING AND FINISHING

4 JOINING AND FINISHING

In a bucket, prepare grouting mortar with a mixer until a homogeneous mixture is obtained. Wait a few minutes before using it.

Insulating panels on the ground: insulating

For ease and speed, pour the mortar into the joints. Fill them carefully with a trowel.

Insulating panels on the ground: ground

Remove the excess mortar with a damp sponge, cleaning it regularly with clean water. Use this sponge to smooth the joints.

Supplies
• Gray cement 32,5 Calcia
• Masonry sand 0/4
• Welded Mesh
• Cleats and wooden wedges
• Insulating floor panels
• Disconnection band
(Perimousse Knauf)
• Weber tile glue
• Jointing mortar
• Natural stone (2 cm thick)

Soils: eight powerful insulation

Panel, block, interjoists, granules... The performances are at the rendezvous. But some products are particularly suitable for underfloor heating.

Insulating panels on the ground: insulation

clever
A flexible wood fiber panel is here associated with a solid wood profile. In addition to improving the thermal insulation of the floor (conductivity 0.045 W / mK), this system is designed to be covered with a solid wood floor whose nailing is done on the profiles. Pavatherm Profile, Pavatex, € 13.90 / m2. Wholesalers.
THE PLUS: dry laying and high walking comfort.

Insulating panels on the ground: panels

Eco-material
The compressive strength of these blocks allows their use in insulation of floors and walls. Made of 100% hemp (hemp straw) and hydraulic lime, they offer very good heat resistance (from 1.4 to 4.2 m2.K / W). Blocks (30 x 60 cm for 100 to 300 mm thick) lay flat and dry without joints or mortars. They can be covered directly. "Hemp block" Chanvribloc, from € 29.40 / m2. Wholesalers. THE PLUS: no volatile organic compounds (VOCs).

Insulating panels on the ground: panels

High density
Made of expanded polystyrene, this panel is recommended for the thermal insulation of floors and floors on the ground, basement, crawl space, etc. It is particularly suitable for heated floors. Its implementation is done by interlocking (grooves and tongues). Offered in a rectangular format of 100 x 120 cm, it comes in 9 thicknesses (from 31 to 93 mm). It displays a thermal conductivity of 0.031 W / mK. "Eps.sol Plus", Isover, up to 10 € / m2. Wholesalers.
THE PLUS: an embossed grid serves as landmarks for laying the frames or floor heating tubes.

Insulating panels on the ground: panels

Great resistance
This insulating material is used for the thermal and acoustic insulation of floating screeds incorporating a floor heating system. Composed of stone wool, mono density, rigid and coated with a reinforced aluminum vapor barrier, it is very simple to implement and has a high mechanical strength. It is available from 40 to 100 mm thick for a thermal resistance between 1.05 and 2.6 m2.K / W. "Rocksol Premium aluminum", Rockwool, from 13.50 € / m2. GSB and trades.
PLUS: for any type of soil with an operating load up to 500 kg / m2.

Insulating panels on the ground: ground

Light filling
Based on perlite, these granules are intended for the insulation of hollow spaces (beams, roofs...). Light, non-combustible and rot-proof, they are resistant to rodents and insects and allow the diffusion of water vapor. They require the prior installation of an anti-creep membrane (which does not deform). Thermal resistance up to 4 m2.K / W on 20 cm thick. Can not be used to level a floor. "Thermal insulation in bulk", Fermacell, about 18 € / bag of 100 l. Trade and mail order.
PLUS: very fast implementation.

Insulating panels on the ground: ground

To project
Dedicated to floors and intermediate floors, this insulation based on polyurethane spray foam forms, after expansion, a rigid layer ready to receive a screed (traditional, fluid, floor heating, etc.). Its implementation is carried out by projecting successive layers until the desired thickness (maximum 120 mm) is obtained. Thermal resistance up to 4.60 m2.K / W. "Pure Isolate", Isolat France, 27 € / m2 in 6 cm thick. Wholesalers.
PLUS: under technical advice from CSTB.

Insulating panels on the ground: insulating

Extruded polystyrene
This type of insulation board (1.2 x 0.6 m for 30 to 80 mm thick) is suitable for ground-level or crawl space. It is made of extruded polystyrene foam (XPS) and has rebated edges that make it easy to install. Its smooth surface also dispenses with the laying of a flexible and resistant film (Polyane). Insensitive to humidity, it has a very good resistance to compression and deformation (creep). It offers good thermal resistance (from 1.05 to 2.75 m2.K / W). Its design allows a sealed installation of the tiles on fresh screed. "Floormate SL-X", Isover, from € 10.80 / m2. GSB and Negotiates.
PLUS: compatible with any type of underfloor heating (water, electric, reversible).

Insulating panels on the ground: insulating

Coffrant
This expanded polystyrene interjoist for prestressed beams is molded in the shape of a vault. It is intended for formwork and light thermal insulation of low floors on crawl space, high basement floors and intermediate floors. It exists in fireproof version for basements with unprotected underside. "Placo Voute", Placo, from 5 € / ml. Wholesalers.
THE PLUS: light and easy to cut.


Video Instruction: How to install Thermano insulation boards on floors