External Wall Insulation: the project begins…

I just wanted to take a moment to let people know that amidst the world’s problems, good stuff is happening.

And for me that good stuff is the start of installation of my long-awaited External Wall Insulation.

The idea of insulating a house from the outside is very simple in principle. In fact it is obvious. But in practice there are many steps required to ensure a weather-proof installation that will look smart when finished and last for a long time. That’s why I have hired the professionals at Be Constructive to do it!

Here are some pictures of the project in progress.

The back of my house. Click for a larger view

The picture above shows the general view of the back of the house with the insulation partially applied. Notice the dark red paint on the existing wall which enhances the adhesion of the insulation and the way the insulation is carefully cut out around the windows and the external tap and water drain.

The picture below shows the external tap and drain which have been extended beyond the thickness of the insulation. Expanding foam has been used to keep the system air-tight.

Detail showing the way the external pipes are extended to allow for the insulation. Click for larger version.

The picture below shows more detail of the window including the protective films applied during construction. You can see white ‘webbing’ around the windows which is called an ‘APU bead’ and its clever function (described in this video) is to give a neat seal between the window and the render.

Details of the insulation around a window. Click for a larger version.

The picture below details of the way the insulation is initially applied to the wall. The insulation consists of two boards of 50 mm thick Kingspan K5 which have been glued together to make a ‘dual-board’ which is 100 mm thick. This ‘dual-board’ is then stuck to the wall using an adhesive mortar. When this is dry – perhaps tomorrow? – the boards will be mechanically fixed to the wall using low thermal conductivity supports.

Details of the way the insulation is initially stuck to the wall. Click for a larger version.

Having considered this for this for such a long time, I am very excited to finally be making progress.

Within a few months I will find out whether or not my calculations were correct! I will keep you updated.

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2 Responses to “External Wall Insulation: the project begins…”

  1. Peter Says:

    The EWI is looking good. For any of your thermal models have you developed a model estimating how much warmer the sun makes your house (solar heat gain coefficient)? I guess relevant factors would be latitude, size and direction of windows and transmittance of the glass?

    • protonsforbreakfast Says:


      Thanks for your comment. In short, ‘No’. Why not? Well because its hard and because I suspect that – for my house and its glazing – solar gain is more important in the summer when I want to minimise its effect.

      Our house is situated with a large wall facing south nut our neighbours block most sunlight on that wall. At the north we are attached to our other neighbours. So solar gain is mainly on the east and west walls. In the winter – due to the streetscape – there is only poor direct illumination of either face.

      But in the summer – when the Sun rises north of east and sets north of west, both east and west walls get considerable insolation and can make the rooms uncomfortably warm. So I am considering blinds (internal and external) to control this.

      I’ll post an update on the EWI soon.

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