FAQs

• How much will cavity wall insulation cost?

  • The cost depends on the size of your house, however, with subsidies, it will usually cost around £200– which can pay for itself in approximately 1.5 years.

• How is cavity wall insulation installed?

  • Small holes of about 20mm in diameter are drilled about 2 metres apart in the external brick wall where the horizontal and vertical mortar joints meet. Insulation is then blown along a flexible hose into the cavity through these holes.

• Doesn't it make a mess?

  • No. All work is carried out externally through small holes in the brickwork joints. A small amount of dust is created when the holes are drilled. The cavity wall insulation is then blown into place using a hose, straight into the wall, so there is no dust or spills.

• How are the holes filled?

  • The holes used to inject the insulation are filled with matching mortar and are barely noticeable.

• My house is rendered, won't cavity wall insulation mess up the render?

  • The holes drilled to inject the cavity insulation are only about 20mm in diameter and are filled with mortar after the insulation has been injected. The installer will match the existing render. If the render is painted, the filled holes should be touched up with matching paint when the mortar has dried.

• How long does it take to install cavity wall insulation?

  • Most homes can be insulated in about 3 hours, but larger houses may take a whole day.

• Doesn't cavity wall insulation cause damp?

  • No. Extensive tests have shown that Knauf Supafil cavity wall insulation does not allow water to pass across the cavity. Supafil cavity wall insulation also contains a water repellent. Before installing the insulation, the empty wall cavities are inspected for obstructions with a special tool called a boroscope. Any obstructions are noted and cleared by the installers before the insulation is injected.

• If my house was built with a cavity, surely it's there for a reason?

  • The purpose of the cavity is to prevent rain that soaks into the outside brickwork from crossing to the inside of the wall. The cavity interrupts any water that soaks through the brickwork and drains it to the bottom of the wall where it drains to the outside. Injecting mineral wool insulation into the cavity still allows water to drain to the bottom of the wall. Knauf Supafil cavity wall insulation contains a water repellent and so does not absorb water. Extensive tests have shown that Knauf Supafil cavity wall insulation does not cause water to pass across the cavity.

• How do I know if I've got cavity walls?

  • Most cavity walls are identified by two factors.
    
    1. They are about 10 1/2" to 12" (270mm - 300mm) this overall ( You can measure this at a door opening).
    2. All the bricks visibly on the outside of the walls are all 9" (225mm) long (except at corners and openings).
    Solid walls have repeat patterns of 4" (100mm) wide bricks as well as 9" (225mm) long bricks over the main area of the wall.  The walls are usually a little over 9" (225mm) thick, although in larger properties the walls can be 13 1/2" (330mm) thick.

• Can I install cavity wall insulation myself?

  • No. This is because specialist equipment is needed to install the insulation into the cavity and it's important that the cavity is fully filled with the correct density of insulation. This is why only trained and approved installers are used so that a guarantee can be given.

• My house is semi-detached / terraced and my neighbour(s) doesn't want cavity wall insulation.  Can you still insulate my walls?

  • Yes, your house can still be insulated. The installer will need to form a hole at the top and bottom of the wall to insert a spacer at the junction between the two houses. This prevents insulation being blown into the cavity of your neighbour's house.

• I've got a timber framed house - can I still have cavity wall insulation?

  • It's not possible to inject cavity wall insulation into timber framed houses however we can carry out loft insulation.

• I live in a flat on the 10th floor of an apartment block, can I get cavity wall insulation?

  • It's not practical to insulate a single flat in a block. If the property has cavity walls, the whole building should be insulated.

• How much will loft insulation cost?

  • The cost depends on the size of your house, however, with subsidies, it will usually cost around £250 to install yourself – which can pay for itself in just over 2 years.

• How much loft insulation do I need?

  • To meet current Building Regulations you need 270mm of mineral wool insulation. 100mm between the ceiling joists and 170mm laid over the joists.

• How do I find out how much loft insulation I have?

  • Simply push a tape measure or ruler down the side of a piece of loft insulation until it hits the plasterboard ceiling and read off the depth.

• I have lots of rubbish in my loft. Do I need to clear it out or will the installer do this for me?

  • Yes, you will need to clear the roof of any rubbish or stored objects before the insulation is installed.

• I want to use my loft for storage, how can I do that if it is insulated to the depth recommended?

  • Your installer can also lay new, innovative loft boards called Supadeck to provide storage space. Click here to view.These are laminated boards made from Polyfoam extruded polystyrene and moisture resistant chipboard designed to be placed on top of the ceiling joists instead of the 170mm mineral wool insulation. You will need a loft hatch which is minimum 600mm x 600mm.

• How long does it take professionals to install loft insulation?

  • It takes about 2 hours for an average sized loft.

• How long would it take me to insulate my loft?

  • Allow about half a day once you have bought the insulation. Remember - you will need one layer of 100mm between your roof joists if you don't have any insulation, then a second layer of 170mm on top (cross layered) to comply with current building regulations. Measure the area of your loft and look at the packaging label for the area contained in a roll.

• Why wasn't my house built with cavity wall insulation and the right amount of loft insulation?

  • Houses comply with the building regulations that apply at the time the property is built. Since the oil crisis in the early 1970s, the insulation standards in the Building Regulations have been progressively upgraded. If your house is more than 10 years old, the chances are you could benefit from more loft insulation.

    The amount of insulation required in lofts has gradually increased over the past 50 years as energy prices have risen and it’s been more widely recognised that thicker insulation brings significant improvements to the energy efficiency of homes. Current building regulations recommend a minimum depth of 275mm, so it’s not surprising that many older homes do not comply with current regulations.

    You can easily check if your home is up to the latest regulations by lifting the loft hatch and measuring the distance between the top of the insulation and the board below.

• Is it true that everyone in the UK is entitled to subsidised insulation?

  • Yes, everyone is entitled to a subsidy and some people can even have free installation. Why? Because the UK Government is obligated to reduce greenhouse gas emissions by 2010 as part of the Kyoto Protocol. One of the easiest ways to achieve a large reduction in greenhouse gas emissions is through increased home energy efficiency. The Government has stated that cavity wall insulation and loft insulation are the most effective methods which is why they have legislated for power/energy utilities and power companies to provide subsidies.

• I live in a rented property, can I still get my walls and loft insulated?

  • Yes, people living in rented property can get their homes insulated, but you must get the permission of the owner or landlord.

• OK, I'd like to get my walls and/or loft insulated using Government subsidies, what do I do now?

  • It's easy! Ring Estate Energy on 0800 988 3301

• How can insulating my house help solve Global Warming and Climate Change?

  • Well insulated houses use less energy to keep them warm. This means that less carbon dioxide, a greenhouse gas, is released into the atmosphere from burning of fossil fuels (coal, oil and gas) in our power stations and central heating boilers. Global warming is occurring because large volumes of greenhouse gases - including carbon dioxide - are accumulating in the Earth's atmosphere. This causes the planet's average air and ocean temperatures to increase and sea levels to rise, resulting in increasingly severe weather conditions. This effect is called climate change and it's already happening. By improving the insulation of your home, you will be playing your part in reducing the effect of global warming.

• What benefit will insulating my house give me and my family?

  • Insulation has many benefits:

    1. Your home will be warmer and more energy efficient.
    2. Your should make savings on your heating bills.
    3. Your heating system will emit less carbon dioxide, the greenhouse gas that causes Global Warming.
    4. Glasswool insulation will also reduce outside noise and increase resistance to fire.
    5. Glasswool insulation is made with recycled glass and is a sustainable product which is light on the earth's resources. It was awarded an A rating in the BRE's Green Guide. Requiring no maintenance, glasswool will last indefinitely and can even be recycled and reused again if removed from a building.

• I make sure my energy comes from 'Green' sources, like wind and solar panels - surely I don't need to insulate my home to help the environment?

  • Well done for using energy from green sources. Renewable energy sources, like wind power, produce electricity and solar panels are part of the solution if we are to reduce emissions of greenhouse gases and tackle climate change. Although solar panels are good for providing hot water, they do not produce water that is hot enough for central heating. Most homes are heated by gas or oil, and when it's burnt in your boiler it emits carbon dioxide, a greenhouse gas. By improving the insulation of your home, you will be reducing your energy consumption and therefore playing a greater part in reducing the effect of global warming.
back