Woolly Loft Insulation

Having completed the wall last week (at last), I found myself curiously relaxed this week.  When the weather is OK I will finish the gates, but they are secure and useable for now, so what to do?  Then I remembered my list (from August) of the tasks that I wanted to do before winter.  Most of these were left from last winter as the extension and the wall have managed to fill most of my time, as well as using most of my energy.  I am painfully aware that jobs like finishing the bathroom and the bedroom wardrobe have literally not been touched since we moved in (July 2011); happily, 'er indoors has been most patient but I'm aware that I can't rely on that indefinitely.

Looking at the weather forecast, it was easy to decide that the loft insulation was top of the list.  A long time ago I opted for a "cold roof" which means laying the insulation onto the joists and ensuring that the loft space above is well ventilated; I bought lots of "Thermafleece PB20" almost TWO YEARS AGO with the intention of laying it as soon as possible after we had plastered the ceilings.  However, things often don't work out as you expect, do they?  This stuff isn't cheap but it is far preferable to fit something like this in an old building because it's breathable, whereas that modern stuff actually prevents the passage of water vapour and it never dries out if it gets soggy. I managed to do about two-thirds of the loft before the onset of winter last year, but left the difficult bit around the hatch until last.  Now it was time to tackle this.

"Thermafleece PB20" is actually 60% British sheeps' wool and 40% recycled polyester which gives it body.  It is much nicer to handle than man-made stuff as it doesn't irritate your skin.  However, I found on the first two occasions I used it that it can irritate your throat (or perhaps that was the dust in the loft); I developed a cough in the following week each time and so I then decided to always use a face mask - this has worked!

It is however more difficult to cut than other modern stuff, and you can't tear it easily.  It comes in compressed rolls and I realized that it was far preferable to try to cut it whilst still compressed.  I used an 8" carving knife for the cutting, with frequent pauses to re-sharpen it on a steel.  I either cut it on the roll by piercing the roll radially many times with the knife and then hacking at the remaining bits, or else by laying it on a board and slicing it whilst also trying to keep it compressed.  Both these were nevertheless somewhat trying procedures, as well as being tiring on your arms.  Annoyingly I found an easier way this week, only about an hour before I finished. I found this by accident as I was cutting off the end a piece which was going to fit up to a joist; I laid it over the joist and put another piece of wood under the insulation so that I was cutting between the pieces of wood.  For some reason cutting down and through the fleece was very easy and effective.  What was a two minute job became a ten second one!

I have laid three layers: a 70mm layer between the joists, and two 100mm layers over the top.  Indeed, this seems a bit "over the top" but the levels of insulation recommended have increased since the days of a simple three inch layer of horrible fibreglass stuff.  The thickness of the top layer can be seen in the photo on the left. Note that in all these photos there is a good gap between the end of the insulation and the roof itself, as ventilation is important (contrary to those who would like us to live in sealed boxes!).

I had a spot of bother when doing this job in 2011 as I wanted to board the area under the roof light.  Unfortunately this was near the central internal wall and the joists on the front of the house were larger than those on the back, so you can imagine the issues I had with relative heights of joists, insulation and board.  That was when I ran out of time and energy over a year ago, but this time I persevered and have succeeded.

The last job I had to do was to fit the loft hatch and add some insulation on that as well, as it was probably a major source of draughts last year.  Hopefully the expense of this stuff will be borne out by the improvement in the warmth of the house and a reduction in heating bills over the duration of our retirement.  You can but hope!