Cavity Wall Insulation

Cavity Wall Insulation

Service Overview

Many houses built over the past number of years have no cavity wall insulation or have an empty cavity with a dry lining slab on the inside of external walls. The empty cavity can be filled using Envirobead Cavity Wall Insulation, improving the houses’ ability to retain heat greatly. An SEAI grant of €300 is available towards this work. Click here for details

The installation process is quite simple. There are a series of 22mm holes (about the size of a euro coin) drilled strategically in the external walls. The Envirobead is pumped in at these points with an adhesive added at the point of entry. When finished, the holes are filled with cement and a dye is used where necessary.

The table below shows u-values for some typical cavity wall construction before and after ploystyrene bead is installed. The term u-value is the rate to which heat passes through a wall, the higher the u-value the more rapidly heat is transmitted through the walls.

Cavity Wall Construction Cavity Width Un-insulated u-value Insulated u-value
Brick/Cavity/ Block/Plaster 50mm 1.40 W/m2K 0.49 W/m2K
Brick/Cavity/Block/Plaster 60mm 1.40 W/m2K 0.43 W/m2K
Brick/Cavity/Brick/Plaster 50mm 1.46 W/m2K 0.50 W/m2K
Brick/Cavity/Brick/Plaster 60mm 1.46 W/m2K 0.43 W/m2K

Popular Questions

Below is a sample of projects we have carried out where the house has a brick work finish. The holes when filled are not very visible.

It may be necessary to carry out a boroscope test where it is uncertain as to the existence of cavity wall or cavity block. It won’t cost you anything to get Hometherm out to give a free quote and to determine if your home has a cavity suitable for filling with Envirobead.

If your house was built prior to 2006 you can avail of a €400 grant towards the cost of Cavity Wall Insulation with Envirobead. For further information go to our section on SEAI / Government grants.

One of the primary functions of a cavity is to stop driving rain and dampness from transferring from the outer leaf of the wall to the inner leaf. Water must be drained away and not cross over the cavity. Using polystyrene bead ensures your cavity works as effectively as it did before polystyrene bead insulation is introduced to the cavity. Between each bead there is a small space for water to drain down through the beads naturally, as illustrated in the graphic below. Polystyrene does not soak water. e.g. Polystyrene cups are used for tea, coffee etc.

Yes. Imagine a cup made of polystyrene full of boiling tea. You can still hold the outside of the cup and not burn your hand yet the thin wall of the cup is holding the heat of the coffee inside. The cup is only 3mm thick and your cavity is many multiples of this.

Holes are drilled in the external walls in an NSAI (National Standards Authority of Ireland) approved pattern and the bead is injected into the cavity under high pressure. (Click here for NSAI Certification). Through gravity and this pressure the bead naturally flows to the bottom of the cavity and continues to fill upwards. The beads will continue to fill any available space. When the cavity is full pressure builds internally and back pressure automatically stops the injection gun. (Just like when you’re filling petrol)

National Standards Authority of Ireland

Hometherm are NSAI approved installers of Cavity Wall insulation

Irish Sourced Bead

Hometherm have partnered with EnviroBead to provide our customers with Irish manufactured Polystyrene Bead, which has the top thermal conductivity of any polystyrene bead in the Irish market. EnviroBead maintains the function of the cavity, is free draining to allow the wall to breath. Between each bead there is a small space for water to drain down through the beads naturally. Polystyrene does not soak up water. E.g. Polystyrene cups are used for tea, coffee etc. There is a 25 year guarantee with Envirobead Cavity Wall Insulation. For more information on Envirobead click on the logo to go to the Envirobead site.