Insulating your loft has obvious benefits, reduced heating bills in the winter, cooler in the summer, fewer drafts etc. The method you choose to do the job is not so obvious. There are a multitude of products available from the more common glass wool and extruded polystyrene to the more eco friendly cotton or wood fibre batts and plenty in between. They all have their pros and cons and dependent on the application, budget and insulation requirements, they each have their place.
In my case I needed to insulate a loft with awkward access but no restriction on the thickness of the insulation. Some insulation materials have better insulative qualities and can provide similar levels whilst being thinner. The downside is that they are more expensive pro rata. So if you have the space and you are working to a budget you don't need to think thin.
In this case due to the access restriction I chose to use dry blown cellulose, it's a great insulator and as you can see from the video, it's a breeze to install.
Insulating a 40 square meter space at a depth of 38 cms including the cost of rental of the equipment but not delivery (I collected it myself) came to just over 20 euros per square meter.
Using fibre glass rolls (probably the cheapest option) to achieve the same u value (see below) would have been around 17 euros per sq meter.
The benefit of the blown fibres is mainly the ease of installation and the fact that there are no gaps or thermal bridges. Two of us were able to easily complete the work in half a day and it's a much cleaner and more pleasant operation that crawling in to all those hard to reach areas with large fibre glass rolls.
If you have any questions on the subject please feel free to ask in the comments below and I'll do my best to answer them for you!
A ‘u’ value is a measurement of heat loss
Low ‘u’ values mean less heat loss
Each element of a wall has its own ‘u’ value, to calculate the overall ‘u’ value, we use ‘R’ values.
‘R’ values work in the inverse and can be added together
A ‘u’ value of 0.5 is equivalent to an ‘R’ value of 2 (1/0.5=2)
Cold or Thermal Bridges – a point for heat to escape and where condensation may form. Found where there is a break in the insulation such as un-insulated joists. Also found at corners, around doors and windows, where metal pipes cross insulation and where there is a disruption of a wall cavity.
Eliminate cold bridges by careful insulation – ensure loft insulation covers joists, insulate around pipes and add extra insulation at corners and the bases of external walls.