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Suitable for the insulation of vertical walls, this technique combines polystyrene beads and a binder. Even if the equipment and products are not yet accessible to individuals, this process is not without interest...

Isolate with coated polystyrene beads

Necessary material

  • drill
  • saw
  • Bell
  • perforator
  • screwdriver
  • unscrewing
  • coating knife
  • float
  • trough
  • cutter
  • saw for plasterboard
  • up plate
  • great rule
  • spirit level
  • metal shears

Difficulty: 4/4
Cost: 35 € / m2 on average (insulating injection) excluding doubling drywall
Time: 7 h per 100 m2

The owner of this building wanted to keep the facade in its own juice. The insulation from the outside was therefore excluded. She also wanted to undertake insulation work at low cost and in winter! The chosen solution is a new process ("Inject-Styrene"), developed under the control of Socotec *, and silver medal of the Lépine 2011 competition.
* Process Control Office.

Drying: 72 hours maximum

The process is simple. of the expanded polystyrene beads (PSE) of 2 to 3 mm in diameter, coated with a binder based on acrylic polymer are injected behind lining walls (brick, plasterboard or tiles...). The insulation thus completely fills the space between the wall and the partition, eliminating thermal bridging and preventing moisture penetration. In addition, he espouses all forms of wall. Dry in 48 to 72 hours depending on the thickness, it strengthens the strength of the walls by eliminating the spring effect.

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A solution according to RT 2012

Its performance is interesting since the reported heat transmission coefficient is 0.039 W / m2.K, with a density of 18 kg / m3. To meet the requirements of the thermal regulation (RT 2012), the insulation must have an average thickness of 11 cm. But the process also works in "voids" ranging from 3 to 40 cm.
In mainland France, some 20 companies are currently approved to implement this process. Part of the site (the bulkhead) can however be done by an individual.

Laying drywall

Laying drywall

  • After screwing the rails to the floor and to the ceiling, fit and then fix the uprights between the profiles, with a distance of 60 cm.
  • The type of fixation must be adapted to the nature of the support.

Insulate by injection of coated polystyrene beads: coated

  • Between the wall and the studs, the spacing is about 11 cm.
  • The old wall covering is left in place.

Insulate by injection of coated polystyrene beads: beads

  • After having cut the reservations for the passage of the ducts, position the drywall then screw them on the uprights.

Insulate by injection of coated polystyrene beads: polystyrene

  • The injection holes must be made by the professional responsible for the injection, at a maximum of 50 cm from the floor and the wall for the 1st hole, then spaced 90 cm (both height and width) over the entire wall.

Insulate by injection of coated polystyrene beads: injection

  • Apply a calico embedded in a coat of plaster.
  • Fill the joint well.
  • Let dry and then repeat the operation.
  • Also hide the screw heads.

Insulate by injection of coated polystyrene beads: insulate

  • It is imperative to plug the least openings in the different bookings previously prepared.
  • Garnish with well-packed paper.

Injection of the insulation

Injection of the insulation

  • The air outlet is connected to the site compressor, equipped with a pressure regulator that delivers dry air (80 m3minimum) at a pressure between 3 and 5 bars.

Insulate by injection of coated polystyrene beads: coated

  • The pressure pot is filled by carefully filtering the binder using a funnel equipped with a filter.
  • The least foreign particle would have a detrimental effect on the final result.

Insulate by injection of coated polystyrene beads: injection

  • The regulator is used to check the pressure to obtain a mixture of 5 l of binder for 1 m3 of balls.

Insulate by injection of coated polystyrene beads: polystyrene

  • The bag of expanded polystyrene beads is installed near the room where the injection will be made.
  • The pipe is placed at the bottom of the bag. He must always be in contact with the balls.

Insulate by injection of coated polystyrene beads: coated

  • The flow rate of the binder in a measuring jug must be checked by means of a stopwatch.
  • The goal is to get 5 liters of product in 15 minutes.
  • In this way, the agglomerate will be as homogeneous as possible.

Insulate by injection of coated polystyrene beads: injection

  • Just before starting the injection, the gun is carefully connected to the inlet hose of the balls to avoid the dispersion of the balls on the ground, in case of mishandling.

Insulate by injection of coated polystyrene beads: polystyrene

  • The gun is positioned in the intended opening and the mixture is injected starting with the lower parts.
  • The progression is done by going up to fill the spaces as well as possible.

Insulate by injection of coated polystyrene beads: coated

  • It is important to fill the walls level by level all around the room, for a good homogeneity.

Insulate by injection of coated polystyrene beads: coated

  • Last injection points: the highest parts below the ceiling.
  • When the space is full, the injection stops itself, which eliminates any risk of cracking of the partition.

filling with finished polystyrene beads

  • Once the filling is complete, the gun is removed: the balls appear in the opening. They remain welded together thanks to the binder.

Refilling injection points

Fill the holes with plaster

  • Generously fill all the holes with sealant applied to the knife.

calico tape

  • Apply a strip of calico (previously moistened) on the fresh plaster, using a spatula, removing all air bubbles.

Insulate by injection of coated polystyrene beads: coated

  • Put a second layer of plaster on the strip and smooth carefully.
  • After drying, sand lightly to obtain a flat surface.

Styrofoam balls in construction vacuum

Our house dates from the 1970s is double-walled. Is it wise to blow polystyrene beads into this building void?
Christian Pessey's answer:
The constructions to double wall are very comfortable and especially very healthy, because perfectly ventilated. On the other hand, they are not very well insulated. Inflating insulating beads is not effective, the vacuum between the wall and the double wall generally not exceeding 5 to 8 cm. In addition, the insulation tends in this configuration to settle over time. You will also lose the benefit of building ventilation. I advise you rather insulation reported from the inside or, better still, from the outside.


Video Instruction: Snug as a Bug - Cavity Wall Insulation.mov