Green homes guide: Insulation

Article, Energy & Housing

Thermal Image House

Insulation: the best place to start

Heat Loss Diagram

Insulation is possibly the easiest and most cost-effective way of reducing your home’s energy consumption. It can help in reducing your bills, save CO2 and will give you and your family a warm comfortable glow knowing that that you’re doing your bit for the environment.

Since the 1970’s government and industry have produced various iterations of pictograms showing how heat escapes through a poorly insulated and draughty home.  So, if you’re serious about reducing your carbon footprint, insulation should be your starting point as its probably the cheapest and easiest thing to do.


Loft Insulation

Loft Insulation2Since the 1960’s the recommended thickness of loft insulation has risen over the years from the original 65mm, to the current building regulations requirement of 270mm for new builds and is also recommended for retrofitting purposes. However, depending on the circumstances of your own particular property you may wish to exceed the current requirements, as there’s a good chance the regulations will be raised again in the not too distant future. You can find out more on loft insulation from the Energy Savings Trust website or this handy loft insulation fact sheet from the Centre for Sustainable Energy.

The most common and cheapest type of loft insulation is Rockwool. This is laid between the joists up to the top level, then at a 45-degree angle for the remainder, up to a minimum of 270mm. This is an easy DIY job not requiring any special tools except perhaps gloves, a boiler suit or that old pair of dungarees you’ve been meaning to take to the charity shop, and a face mask.

CosywoolAlternatives are sheep’s wool and sheep’s wool blended with polyester.  These are more “natural” but more expensive.

Cellulose insulation is another option usually made from recycled newspaper and cardboard and treated with a fire retardant and blown into the attic. This type of insulation is more common in Europe and North America than the UK.

However, these types of insulation can’t be compacted down to work effectively so it’s as waste of time and money doing this and then chucking a load of suitcases and other stuff on top of it. Be ruthless and get rid of all that tat you’ll never going to use by donating it to a local charity shop, Steyning Freecycle  or one of our “Give Your Stuff Away Days”.

If your kids have flown the nest and left you holding on to their stuff give them a deadline to get it out.  Tell them that Greta is on their case!

If you’re not able to get rid of all of it, you can still store stuff in the loft by building a raised platform using loft stilts and boards.  It’s a relatively easy DIY project for the average homeowner if you have basic DIY skills.   The LoftZone website will give you some ideas.

Img 0769If you insulate between the joists, you’ll have what’s known as a cold roof. If you’re thinking of using the loft as a full or part time living area, or workspace then don’t insulate the floor as it’ll be a bit chilly up there. For this scenario the best option is to insulate between the rafters using sized pre-cut rolls of Rockwool or insulation boards.

Insulation boards such as Celotex or Kingspan can be cut to size and “friction fitted” between the rafters. This is easier and less itchy than using rockwool.  The photo shows a double layer of insulation – which makes for a extra cosy loft.


Spray on Loft Insulation …….. maybe!

A lot money goes into marketing spray on insulation between the rafters. This works well for insulation purposes if you have a seamless roof such as fibreglass, rubber or zinc. However, it’s not recommended for tile or slate roofs as the downside is, you’ll have a “bonded” roof making it very difficult to replace damaged/broken tiles or slates. It also makes the installation of solar panels very difficult should you decide to install these at a later date to a tile or slate roof that’s been foam sprayed.


In summary

  • Loft Insulation is easy!
  • Loft Insulation is cheap!
  • Loft Insulation will de-clutter your life!
  • Loft insulation will make you a new person!
  • Loft Insulation can be done this weekend!

So, get on it with a trip to Wickes, B&Q or their websites and place your order.  They even deliver so no excuses!


cavity insulation 16 300Cavity Wall Insulation

If your house was built after 1930 the chances are it has cavity walls.  If they’ve not yet been insulated, this will be one of the cheapest and most cost effective ways of reducing your energy bills and carbon footprint.  But there are potential snags, so you need to get it done properly.

The Centre for Sustainable Energy have produced a cavity wall insulation fact sheet.  They quote a typical cost of £500 for a 3 bed semi (2019 prices), with a payback time of just 3 years and annual carbon savings of 831kg CO2e.


Underfloor Insulation

Uninsulated floors can also be a major area for losing heat, and a source of cold draughts.   How easy this is to fix depends on how your house is built. Here’s a link to the Centre for Sustainable Energy floor insulation fact sheet on the topic, which covers both concrete and timber floors.


Insulating older homes

The older your home the bigger the challenges in making it really thermally efficient.  But there’s still lots you can do.  Here’s a helpful article from County Life on 10 ways to insulate a period property.