Last summer the Daily Mail published an article claiming that too much insulation installed under the could cause overheating of homes and endanger old people.

Since we are now approaching warmer weather (or what passes for warm weather in the UK), I thought it would be right to tackle this accusation and explain just why the opposite is in fact true!

How does insulation work?

During the winter, the air inside the home is warmer than the air outside. The insulation slows down the movement of energy from the warm area to the cold area, creating a thermal barrier that means your boiler doesn’t have to work as hard to keep the home warm. The thicker the insulation, and the lower the U-value, the better this thermal barrier is and so the slower the heat will escape the home.

During a summers day when the temperature may hit 30 degrees, the air outside is generally warmer than the air in the home. With the heating off, the house warms up gradually through the day as the walls and roof absorb the heat of the day. But because the air outside is warmer the thermal barrier created by the insulation will again slow the movement of heat, but in the opposite direction. Warm air in the loft will not be able to penetrate into the home as easily, whilst insulation in the walls will prevent them from warming the home as quickly as well.

Will insulation make nights too warm?

It is true that if you home is too warm when you go to bed, insulation will slow the release of heat from the property. This is easily negated by ensuring that you keep the home well ventilated, opening windows, for example. Anyone who doesn’t open their windows in a heatwave is asking for trouble – a bit of common sense is all that is needed!

To be honest there are about half a dozen days a year in the UK where we do find ourselves in the midst of a heatwave conditions, but there is normally about 6 months when we need to have the heating on, so on balance it is clearly better to install the insulation and take action when it is too warm rather than visa versa.

Are there any negatives to installing insulation?

Insulation is a safe, important way to make your home more comfortable, and it will help make your heating bills more affordable. There is absolutely no reason why you should not insulate your home, as long as it is done properly and appropriate measures taken with regards to safety.

Poorly installed loft insulation that does not consider your wiring and lighting can cause fires, but this is easily avoided by capping the light fittings and taking care not to cover wires. Any installer worth their salt should be able to do this. For cavity wall insulation, vents are sometimes required to prevent damp and provide sufficient ventilation for the property.

Is air tightness a problem for air quality?

It is important for your home to have good air quality – poor air quality can be hazardous to health. Having said this, some properties with extreme air tightness, like passivhaus buildings, have very good air quality. They utilise natural ventilation to improve the air, so whilst it is worth considering your air quality, it should not be a reason to avoid installing insulation.

Insulation is vital for your home

Wherever you live and whatever the type of property, insulation is absolutely vital. With spiralling energy costs it will become even more so. Make sure your home is up to scratch and don’t let the papers stop you from keeping your home warm and saving you money!

Installing Cavity Wall Insulation

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London has undergone many waves of house building, with each type of home creating their own energy efficiency problems and areas for improvement.

It was 1965, that Building Regulations introduced the first limits on the amount of energy that could be lost through certain elements of a newly built house. However even until very recently, building standards were not sufficient to create what we would consider an efficient property.

Most housing in London was built well before building regulations really took effect and therefore it is fair to say that the majority is poorly insulated and fitted with inefficient heating systems. Yet these are very fixable problems.

There are plenty of ways you can improve the efficiency of your home, whether it be a 1900 Victorian terrace or a 1980s detached house. We thoroughly recommend an energy consultation to work out what is best for your home, as each property really is different and there is nothing better than tailored and personalised advice.

Having said this, you can tell a lot about a house by its age. As such, we can make some recommendations on the best steps for your home. It goes without saying that loft insulation should be up to standard (270mm) before you look at anything else – it really is the number 1 way to make your home more efficient, but here are some other key things you might want to consider to help lower your energy bills:

Pre 1930 London Properties:

• Solid Walls – Seen on almost all Pre 1930’s homes, solid walls are very inefficient. You can insulate with either external or internal insulation and there is funding available to do so.
• Timber floors in the majority of the home with cold solid concrete floor kitchens – It is fairly typical on Victorian terraces to see floorboards in the main area of the property and solid concrete floors in the extension. You should draught proof your floorboards using Draughtex and look at floor insulation – although this may involve lifting up the floorboards.
• Sash windows – Large single glazed sash windows are fairly typical on homes built in this era. Sash window double-glazing is expensive, and there is usually a cheaper option like refurbishment or draught proofing. You can read more on this here. Remember, old properties like this typically have lots of chimneys, so make sure you have them blocked off or use a chimney balloon to cut out draughts here since these cold draughts can very quickly strip the home of any hot air.

1930’s London Properties:

• Cavity Walls – After 1930, cavity walls became standard. This is great news for you, because cavities are very easily insulated and can make a big difference to your bills – they are simply injected from the outside with cavity wall insulation.
• Suspended timber floors  – Most 1930’s homes have timber floors, which can be either insulated or draught proofed.
• Draught Proofing – Once again these homes could well be draughty so it is worth looking at getting your doors and windows draught proofed.

Post war 1945-70 London Properties:

• Flat roofs – This isn’t always the case, but flat roofs became popular post-war, and were rarely well insulated. If you have one, make sure you look into flat roof insulation, this process is not as easy as you might hope, however the Government are currently offering £550 cashback if you were to opt getting this insulation installed via the Green Deal scheme.
• System Built Houses – If you live in a prefab or a flat, you could be losing a lot of heat through the walls. You should look into wall insulation – this could be either cavity or solid wall.
• Flats / Mid-High Rise – Flats present their own problems because the envelope of your home includes other people’s property, although having said that, where you have a party wall with a neighbour there should be no heat loss, so actually if you are in the middle of a block of flats this may actually be an advantage in terms of energy efficiency.

1970’s London Properties:

• Single glazing / smaller windows – Many 1970’s properties have small single glazed windows. Secondary glazing may well be worthwhile considering here.
• Cavity Walls – After the 60’s regulations on new homes meant that some insulation was fitted as standard, but it is still worth checking your cavity walls, as these were generally not insulated.
• Watch out for old boilers / electric heating (off grid / now on grid but still with electric heating) – The 1970’s was a time of energy uncertainty. Some properties were built without a gas supply and therefore use electric storage heaters. Others have even more unconventional heating systems like back boilers, gas room heaters and electric ceiling heating that could be costing you money. Look at whether you can change to gas central heating or take advantage of the RHI for renewable heating such as heat pumps.

Modern London Properties:

If you live in a relatively modern house, your cavity walls should have already been filled, but there are a few things you can still look out for:

• Loft Insulation top-up – Usually these properties have some loft insulation, but it may be worth getting a top up. Building regulations in the 80’s and 90’s was nowhere near today’s standards, so you could still save a tidy sum by getting more insulation.
• Old Boilers / heating systems – Houses around 20 years old may still have the original boiler present. It is really worth switching over to a modern one and is likely to be the biggest way to save on a modern property.
• Renewables – If your home is otherwise up to standard, it may be worth looking at renewable energy. Modern homes are likely to have roofs suitable for solar panels and technologies such as heat pumps work best in well insulated homes like yours.

According to Government statistics, there are currently 5.75m houses in the UK that are still in need of cavity wall insulation. Of these, 4.6 million are classed as having hard to treat cavity walls.

What is a hard to treat cavity wall?

A wall can be classified as a hard to treat cavity if it has one of the following characteristics:

• A building of three stories or more storeys (unheated basements do not count as a separate storey);
• Whether or not the cavity requires remedial work to bring it up to good working order;
• Or the actual thickness of cavity is narrower than normal.

Cavity wall insulation – key facts

Early cavity walls were usually just 250mm thick, which meant that the cavity was 50mm or less. Back when these were being built, there was no thought about insulation – the walls were built with cavities to help stop damp issues, and prevent the water penetrating the inner skin on the wall. With a cavity wall any water that goes through the external skin of bricks would fall down the cavity and dissipate away from the house to keep it damp free.

Since the 1980s, Building Regulations have stipulated that cavity walls are filled when they are built – in most cases the insulation is fixed to the inner skin of the cavity wall, leaving a gap between the outer, external cavity skin and the insulation. This allows any moisture getting through the first skin, to still fall down the cavity.

Fairly quickly, it became apparent that properties without filled cavities could be retrospectively filled – provided the cavity was reasonably big (over 75mm), they could drill lots of small holes in the first skin of bricks and the insulation could then be blown into the cavity.

Retrofitting Cavity Wall Insulation

Retrofitting cavity wall insulation quickly became big business, with lots of suppliers popping up and injecting blown mineral fibre into these large cavities. The blown mineral wool is still used today, and tends to be either Rockwool (made from spun volcanic rock) or glass wool (made from recycled glass bottles). The wool is treated with water repellent during the manufacturing process to help drive the water down the cavity and away from the house.

The issue with this blown insulation is that if there is anything obstructing the cavity, such as a piece of mortar, the wool insulation will get caught and not properly fill the cavity. In addition, the cavity is too thin, the wool will not properly travel down through the cavity when it is injected – until recently this has prevented many insulation retrofits going ahead.

Insulating Hard To Treat Cavity Walls

These walls are referred to as Hard to Treat Cavity walls; in the past the only thing that could be done to insulate them was to attach either external or internal solid wall insulation, which is incredibly costly.

Hard to Treat Cavity Walls and Micro beads

Recently however there has been a breakthrough in this ‘Hard to Treat’ market. Micro beads (made from expanded polystyrene) can be injected into these walls. These beads flow through the wall and don’t suffer from getting caught in the cavity – they can get into even the smallest spaces ensuring that the whole wall is effectively insulated.

These beads are coated with a binding agent prior to being injected into the hard to treat cavity. The binding agent holds the beads in place once it sets and stops the beads escaping the cavity if any remediation work is done on the cavity at a later date – for example a window is replaced.

Using Expanded Polystyrene Beads to insulate Hard to Treat Cavities

These expanded polystyrene beads also have superior insulating qualities compared to the blown insulation, so even if you have narrow cavities; you can still really bring up a walls insulating properties.

The beads are also naturally water repellent and won’t rot over time, and unlike wool insulation, don’t provide any nutritional value to animals so won’t be eaten.

In addition, since the beads are small and flow (almost like a liquid), the number of holes that are required to be drilled is far lower than cavities retrofitted with the blown wool.

So there you have it – even if previously you have been advised that cavity wall insulation was not possible for your property – this may not be necessarily true. These expanded polystyrene beads allow you take advantage of cavity wall insulation, which is a fantastic way to lower your energy bills.

If you would like to see if you can benefit from cavity wall insulation, call us now on 0208 144 0897 and we can send one of our trained energy assessors to drill a small hole in your cavity wall and carry out a boroscopic inspection to determine whether your wall is suitable.

You may also be eligible for a free grant to cover the cost of the installation under the ECO scheme.

 

Cavity wall insulation has been around for years, and it remains one of the best ways to help reduce your energy bills. So we at TheGreenAge thought that we should give you a quick guide on what you need to know so that you can maximise energy efficiency of your home. See the video below for a quick introduction!

How do you know if you have cavity walls?

When we do our Green Deal Assessments with clients in London, we stress the importance of insulating the envelope of the property, which includes the roof, the walls and the floor. The first thing we do therefore is check whether the home has cavity or solid walls. There are several simple ways to check this. 

Understanding the property age

Generally speaking, properties built after 1930 will have cavity walls. Those built prior will have a solid brick walls. But that isn’t definitive as we encounter many semi-detached properties in London suburbia (Harrow, Edgware, Watford, St Albans, Ealing and so forth) that actually have solid walls, despite their age!

Checking the brickwork

Check your brickwork. If you have bricks end to end across the whole wall, it is a cavity wall (also called a stretched bond – see diagram below). If the bricks are a mixture of ‘stretchers’ and ‘headers’ where there are short bricks and long looking bricks, then you have a solid wall (i.e. no cavity).

Measuring the wall thickness

Sometimes walls are rendered, which makes things a little more tricky since you can’t see the pattern of the bricks. If this is the case, you can try measuring the thickness of the wall through a window or doorway. If it is less than 260mm, it is likely a solid wall. Anything thicker is more likely to be a cavity.

Other ways to check is by looking at un-plastered areas of the house (in the staircase, airing cupboards or in the loft) where you should see either a layer of breeze-block or a layer of brick.

Checking for existing cavity wall insulation

So you have a good idea of whether you have a cavity or not. The next step is to check whether it has been insulated. Modern properties built from the 1980’s onward are generally insulated when they are built, since it is now part of standard building regulations. Homes built prior to this date may or may not have insulation. If it was insulated it after construction date it would have been done so by injecting insulation into the cavity through holes in the wall. You can usually spot where these holes have been covered up on a brick wall along the mortar lines.

So what if you still can’t tell? In this case it is time to call in a professional to come to your property and inspect the potential cavity.

When a professional energy assessor (like one from our team) comes round to your property they will undertake a borescopic examination. This involves drilling a small, non-intrusive hole in the mortar (above the damp coursing) and checking with a borescope (a camera on the end of a fibreoptic cable) for any insulation. We show you how this is done in the video below:

 

What could Cavity Wall Insulation do for me?

So you know you need insulation, what is it worth exactly? Typically cavity wall insulation costs around £500-1,000, depending on the size of the property and the walls needing to be insulated.

But it can save you serious money on your heating. A detached or semi-detached property could be looking at savings of up to £500 a year, depending on the occupants and how you use your heating. Terraced properties could expect savings of £200-300.

So the payback here is pretty good. You should save enough in the first few years to cover the initial costs of getting the cavities insulated.

In addition, it is well worth remembering that all evidence points to energy prices continuing to skyrocket – over the last 8 years, energy prices have increased by 10% each year. Therefore the quicker you get your walls insulated the better!

If you would like to read more about cavity wall insulation, see our full guide here.