Insulate the Attic

Introduction:

 

 In summer 2022 energy prices were shooting up. Various websites highlight this as one of the fastest payback and high impact jobs to improve house insulation (eg  https://energysavingtrust.org.uk/advice/roof-and-loft-insulation/) ...

...my only worries were our existing floorboards and attic junk making this a big job. I also worried about the likelihood that everyone else had the same idea and there would be a global shortage of insulating materials.

 

What we had before:

• Approx 100mm of insulation, made up of:
• Central portion of attic (below floor boards) - Kingspan (this has approximately 2x the insulation properties of regular fibre insulation, given the same thickness)
• Approx 100mm of very old fibre type insulation

 

What I added:

• Insulation: "itch free" (https://naturalinsulations.co.uk/product/supasoft-insulation/ ). This was placed on top of the existing insulation to get approx 300mm across the whole attic.
• Loft Stilts (https://www.loftstilts.co.uk/). It is only afterwards that I have realised that there are multiple brands (eg Loft Legs) doing a similar job; I did not do any comparisons before purchase.
• I also needed some screws for the loft stilts, but everything else was existing (floor boards in central portion of attic, large access hatch, lighting, etc)
• Costs:
• Insulation: £1,015 (including shipping)
• Loft Stilts:     £145
• Total:         £1,160

 

The Plan:

• Clear out junk from the attic (hired a small skip)
• Move remaining stored stuff to one end of the attic
• Lift floor boards at the other end
• Add loft legs
• Add insulation - now around 300mm across the attic
• Replace floor boards

One end of the attic complete (you can see attic junk at the edge of the picture)

 

• Move 50% of stuff from one end to the other
• Lift floor boards in the centre, etc
• Move 100% of the stuff to the completed end
• Repeat process on final end
• Re-distribute stored stuff

 

Execution:

• Looking online it seems to be simply a matter or rolling out the insulation. It is all the other things that take the effort and a bigger job than I had at first envisaged
• It was hot and sticky work (Sept/Oct):
• How long did it take? - hard to judge as I did the work at weekends over a few weeks and did not work every day. The work took about 10days, working 4 or 5 hours each day (working longer in the cramped conditions was too much for me).

 

Lessons Learned:

• I wish that I had thrown away more junk - there were some long floor boards, so you needed space beyond the area being insulated.
• Our attic has reasonable lighting in the centre (two strip lights), but still not good enough. In hindsight installing lighting throughout, before I started would have made it easier (& easy with some LED lamps).
• I was worried that loft legs did not look robust enough. I needn't have worried the floor boards structure, with loft legs underneath is rigid and feels robust.

Cross-section view at attic hatch with one loft leg visible - the overall structure feels rigid and robust

 

• There are quite a few useful 'how to' guides on line.
• Using non-itchy insulation was a good move (the limited amount of original fibre glass insulation was bad enough)
• Not doing this at the height of summer was a good move
• We have a relatively large attic hatch with a built in ladder - if you do not already have this, then worth installing ahead of insulating, particularly if you use the attic for storage.
• I needn't have worried about a global shortage of insulating materials - the suppliers website promised 3 days and the insulation arrived in 3 days.

Insulation arrived within 3-days. Despite rapidly rising energy prices, there seemed to be no shortage on insulating material

 

Impact:

• Combined with other changes (small reduction in room target temperatures (1degC in some rooms) and reduced boiler flow temperature from 70degC to 65degC) this looks to be saving ~£300/year (see upcoming blog post with September '23 data) It is difficult to be certain which of these is the biggest impact; my expectation is that the majority of this is the loft insulation:
• We have since restored some of the temperature settings and it has not made that much difference to costs)
• My understanding is that the flow temperature has to be lower than 65degC to make a significant improvement in boiler efficiency (more on that in a future blog post on weather compensation)
• Increased comfort: The house felt warmer (eg in the morning when the heating had been off all night) & also warmed up quicker.
• I think that we can run with heating off completely for longer over the summer/autumn.

 

My summary:

While it was more effort than I had envisaged, definitely worth doing and a good return on investment at perhaps 4 or 5 years.