CAVITY WALL INSULATION
ARE YOU LOSING 33% OFF HEAT THROUGH YOUR WALLS?
Considering that over 33% of heat is lost through our walls, insulting them is a must for heat loss prevention and modern sustainable living.
WHAT IS CAVITY WALL INSULATION
I’ve taken a video opposite that explains the 2 fundamental types of walls that houses are made from in Ireland – 9” Cavity Block and Cavity Walls. In the latter scenario a cavity exists between the outside and inside walls. Historically this 100mm wide void was filled with 50mm of polystyrene insulation (white insulation) on the inner wall to help heat loss. With new and emerging technology the remainder of the cavity can now be pumped to improve heat loss. It should be noted that the modern insulating materials that are pumped into the cavity are far superior than the existing polystyrene insulation.
By reducing heat loss through the cavity, you can substantially save on your heating bills as well as your home having a better insulating rating.
There are a few different types of cavity wall insulation on the market today. Your project's best insulation will depend on your budget and building type. If you are building from scratch, you have many options, including cavity insulation boards or mineral fibre. However, it's not possible to use cavity wall boards in existing properties, you need insulation that can be pumped/blown into the wall.
HOW DOES CAVITY WALL INSULATION WORK
A series of holes are drilled around the outside of the property and the insulation is then pumped in through these holes and fills the cavity. The holes are then plastered and blend by mixing different colour dyes with mortar to closely match the existing finish of the house. If the house is a painted finish then re-painting will be required.
There are 2 types of pumped Insulation widely used in Ireland, both are designed to fill 100% of the wall cavity, ensuring there are no cold spots
1. Bonded Bead
2. Spray Foam
1. BONDED BEAD
As can be seen in the picture Bonded Beads are small “beads” of insulation (expanded polystyrene). They are injected into the wall along with a bonding agent. The bonding agent holds the beads in place giving long-term stability. The cavity wall is still able to breath and as the bead does not absorb moisture there is no damp transfer across the cavity to the inner
wall.
2. SPRAY FOAM
This type of insulation material is the same as that used on Attic Rafters, between floor joists, etc. It's two chemicals mixed together that expand to multiple times their initial volume. It is not as effective as Bonded Bead and we don’t use it. The foam tends to shrink over time and pull away from the structure so it’s easy to get cold spots in the cavity. Also a lot of mortgage companies do not like it and numerous UK clients have been refused mortgages on homes that contain Spray Foam insulation.
ADVANTAGES OF BONDED BEAD INSULATION
- SEAI Grant up to €1,700 Available
- Improved thermal properties
- Improves BER rating thereby increasing the house value
- Fully nZEB compliant
- No air gaps or uninsulated areas
- Completely water resistant — preventing mould or rotting
- External application means little home disruption
- Quick turnaround for a full installation
- Bonded Bead Insulation is suitable for both new and existing properties
CAVITY WALL INSULATION COSTS
The cost of pumped cavity wall insulation per m2 is typically
between €8.50 and €13 per m2.
HOW TO CHECK IF MY HOUSE WALLS HAVE A CAVITY
There are a few different ways to determine if your house is suitable for cavity wall insulation.
-
Thickness of Wall
The depth of the wall will be 300-350mm as the outer block is 100mm, the
cavity is 100mm and the inner block is 100mm. The rest is the render and plaster finish. -
Meter Box
Open the door of the meter box. More often than not you can see the construction of the property by checking where the power cable enters the meter box. Is it solid wall, cavity block wall or cavity wall with or without insulation. It’s only possible to pump a cavity wall.
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Similar houses
If other houses in the area/estate have had their walls pumped with bead, then your house should be suitable.
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Attic View
Although difficult sometimes the cavity may be exposed in the attic at the eaves, wall plate or at the gables where you can check the walls for suitability.
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Vents
Take off a wall vent and you might be able to see if there is a cavity.
CAVITY WALL INSULATION FAQ'S
The cost of pumped cavity wall insulation per m2 is typically between €8.50 and €13 per m2.
Here's a ball-park Property Type Costs Range
2 Bed Semi Detached €1500 - €1,800
3 Bed Semi Detached €1,800 - €2,200
4 Bed Semi Detached €2,200 - €2,750
Bungalow - Survey Required
Absolutely, once it’s done then it’s done forever, saving you money forever.
- Very little interruption as all works are outdoors
- Generally competed in a day
- Increases the value of your home
- Grants up to €1,700 available
Like everything that you get done on your home – bad workmanship is the main problem. Look up company reviews on Google to ensure a good standard of workmanship and Customer Satisfaction. They must also be registered with SEAI. As a process there is very little wrong with Cavity Wall Insulation.
Not if done correctly. However, the source of dampness must be eliminated whether you are pumping the cavity or otherwise. If the moisture ingress is severe and at high level it may flow across the bonded bead and show as staining inside. This is not the fault of the bonded bead but a source of moisture which must be eliminated.
Retrofit - Expanded polystyrene Bonded Bead
New Build – High performance Polyisocyanurate (PIR)