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Tuesday, 30 April 2013

Inside out: the wrong way round

When we move into a new house we tend to do two things:

1. Complete the work detailed in the mortgage agreement (this tends to be things like damp proof courses, underpinning, roof repairs);
2. Decorate in order to make your mark on your new property.

So what you are left with is a nice looking internal environment and a structure that a finance institution is happy with.

There are some issues with this.

1. Firstly, finance companies do not understand the workings of older solid walled properties and so many of their recommendations are pointless / potentially damaging. The money spent on these measures could / should be better used using more permanent solutions, but this is a huge topic that is impossible to deal with in this short post.

2. Decorating over issues like mould, damp, cracks is pretty pointless unless the root cause is also dealt with. I have seen this over and over again where people have spent a lot of time and money making their mark only to find that the mould / damp / cracks re-appear. This is the point of this post.

We would recommend using those initially tight resources to solve the problems with the house. These issues are not limited to what the mortgage company says, so don't be lured into a false sense of security. Use this blog to flush out some potential problems (the indicators are things like dry lining, freshly painted walls etc.)

Most of these issues tend to be on the outside of the house, hence the title of the post! The majority of what needs to be done to a house, in order to make it fault free, is based in chronic poor external maintenance. So have a good look at things like:
  • Re-pointing
  • Cracked / blown renders
  • Raised ground levels
  • Blocked vents
  • Blocked / broken / faulty guttering
  • Rotten timbers
  • Flashing around chimneys
  • Chimneys not protected from rainwater
  • Silicon failure around doors and windows
  • Incorrect paint being used on solid walls
  • Poorly sealed walls around incoming / out-going services
Once the outside of the house has been maintained properly then you can decorate to your hearts content with the knowledge that it will not fail in a few months time.

Remember that in order to keep your house looking good and operating well you will need to use the correct materials and products. Reading this blog will help with that. Also it is worth noting that maintenance is a regular requirement and not just a one off. So every now and again have a good once-around the outside of the house to ensure that all is well; it is easy for guttering to get blocked / fail and for new cracks to appear in cement render, etc.

CADW have a really good website on maintenance. Don't be fooled by the term 'historic', as this applies to all solid walled buildings. See

Wednesday, 17 April 2013

Double or Triple Glazing?

The last post on Vacuum Glazing reminded me of another fact when looking at glazing. Most new glazing have a few energy saving features:

1. Glass coating (commonly known as low E glazing)
2. Low conductivity spacers (the material that keeps the panes of glass apart at the edges)
3. The gaseous fill in the glazing (argon and krypton are examples)

1. Glass coating is a good way of keeping heat in during the night time and winter months and the heat out out during the sunny summer days. The coatings can be applied as either a hard or soft coat, but given that the coating is applied to the inner glazing panel that is within the glazing unit there should be no real wear and tear to disturb its workings. These glass coatings are therefore a cheap and easy way to make your house a little more energy efficient (but the effect is quite minimal in the grand scheme of things).

2. These are physical structures that can help reduce cold bridging between the glazing sheets. This can be reasonably important when looking at high performance windows (but then the high performance window manufacturers know this and will fit them as a matter of course). But if you are specifying more standard glazing it is worth ensuring that you get these edge spacers as they are a physical attribute that will not decrease in their energy saving value over time.

3. The fill of windows actually makes quite a big difference to their performance. So having an argon fill is worthwhile, however be aware that the gaseous fill will, over time, dissipate. So after around 10 years the window will not be performing as well as it did when it was originally fitted. There is nothing that can be done about this, so maybe it is worth thinking about it all in a different way.

One way of getting similar performance to gas filled double glazing is to fit air filled triple glazing. The insulation values between the two are quite similar. Of course a gas filled triple glazed unit will be even better for the first 10 years or so.

Triple glazed windows are more expensive of course, this is because of the additional glass, weight and normally an enhanced frame size. The costs may never recouped from the additional heat load, however if you are trying to get a building to perform well and consistently then it might be worth investigating.

Note that triple glazed windows cut out some of the light coming into the building and if this is important then it might be worth considering installing double glazed windows to the more south facing aspects of the building (this will allow more heat and light into the building) and then have triple glazed to the north. The north facing windows will only even let heat out and so having these are higher performance windows makes more sense.

Tuesday, 2 April 2013

Vacuum Glazing

Pilkington Spacia is one of the new generation of high performance vacuum windows
Vacuum glazing has now appeared on the UK market and will be sold into the heritage market as a highly energy efficient option for windows where thin glazing is needed - sash windows etc.

On the face of it these are amazing windows, very low U values (so very good thermal performance) and easier fitting in thinner, older frames that cannot take modern double glazed units. So all well and good. However, there is a major issue that is not looked at in the brochures - Time.

Nature does not like a vacuum. So what happens to the window performance once the vacuum has failed?? Some of the manufacturers state that there is a 10 year guarantee period and that the windows are expected to last longer. To me I don't think that people will be aware of when the windows are no longer working properly and also the idea that you have to replace your windows every decade or so seems like a waste of resources / money.

I fear that this is a well intended energy efficiency exercise that might have unintended consequences. I think that it will lead to even poorer calculations in EPCs after a couple of years as they will be adjusted to take the windows original value, not its actual value at the time (this would be impossible to calculate easily). Later homeowners will be told that the windows are super efficient, but actually they will probably be very inefficient.

CADW have shown that single glazed windows can be improved radically by using secondary glazing, draught proofing, heavy curtains and shutters. So the expense of fitting vacuum glazing might be better spent on these improvements in the long run.