Cavity Wall Insulation - New Build

The biggest decision to be made with a new home is the level of insulation you will require. We advise a 150mm cavity width fully filled with Envirobead Plus Platinum Bonded Bead giving a u Value of 0.20. This is a vast improvement over the required 0.27.

The installation of Envirobead Cavity Wall Insulation into a building under construction is both simple and efficient. A series of 22mm holes are drilled in the inside leaf of the cavity wall. The holes are then covered by the plaster. The polystyrene bead is pumped in at these points. As it's pumped into the cavity, each bead is lightly coated in a strong glue. When the glue sets the bead will form a solid structure. This ensures that the insulation remains in place if the cavity is ever opened again. After installation, there are realistic savings of 25% of heat loss and a payback time of between four and six years.

Cavity Wall Construction

Cavity Width


Brick/Cavity filled with Envirobead/Block/Plaster



Brick/Cavity filled with Envirobead/ Block/Plaster



Brick/Cavity filled with Envirobead/ Block/Plaster



Brick/Cavity filled with Envirobead/ Block/Plaster 150mm 0.20

I 'm building a new house, can I use Envirobead bead in the cavity?

Yes you can. It is a full fill system accepted by the National Standards Authority of Ireland (NSAI) and meets current building regulations. Click here for NSAI cert.

Is it better than the conventional method of installing insulation sheets?

Yes, because you or your engineer can inspect the cavity during the building process. You will have a cleaner cavity and the builder can keep the wall ties clean.

Will filling the cavity with Envirobead cause dampness?

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.

Hometherm Insulation Bead Matrix

Is bonded bead a good insulator?

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.

Should I get a reduction in price on my builder's labour costs for not installing the traditional insulation sheets?

Yes. By installing sheets it slows the builder up by 8-12%. He has to clean the wall ties, cut and fit the sheets and then clip it in. On an average eight hour day it takes the builder half an hour to one hour a day to put in insulation sheets correctly.

Is bonded bead cheaper than insulation sheets?
Will I see holes in the plaster of the house?

No. Hometherm install Envirobead once your roof and windows have been fitted but prior to the inside wall being plastered. You then plaster the walls eliminating all signs of the installation.

'How do you know when the cavity is full?

Holes are drilled in the external walls in an 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)

Any other questions just drop us a mail or give us a call

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.

ISO Certified NSAI SEAI Registered Better Energy Homes National Insulation Association of Ireland (NIAI) RGI Passive House Consultants FETAC Qualified Energy Installers CIRI Registered CIF