Traditional loft insulation is possibly the most cost effective energy efficiency home improvement that you can make
Traditional homes built in Scotland have different types of roof, these include a pitched, flat and room in roof.
With a pitched roof you would expect to have a flat ceiling above the top floor which is accessed via a loft hatch. Earlier homes were built with no insulation in this area, meaning that around 33% of your heat would be lost through the roof.
From around the 1970’s onwards builders started to insulate these roofs with glass wool of around 50mm, with later homes being insulated by maybe 100mm of glass wool. As time has passed we realised that increasing these levels had a positive effect in reducing the bills further and making the home seem warmer.
If your home has less than 300mm of loft insulation, whether that’s wool, minerals or an alternative insulation then it would almost certainly benefit from a top up or, if there’s no insulation, a complete install.
Generally we try to install 300mm of insulation but the more insulation you install the lower your heating bills are likely to be. Above 300mm the improvements become smaller though, as the heat loss becomes less. That’s why the current recommendation is 270mm minimum.
In general we want to lay 150mm between your joists and a further 150mm across your joists, this offers the most cost effective manner in which to insulate your home.
Many people ask about retaining loft storage and whether they can lay flooring over the installed insulation – the answer to this is no, but there are solutions.
WOOL INSULATION
Wool insulation works best when its not compressed, in fact if you were to lay 300mm of insulation and then compress it back to 150mm then all you have done is pay for 300mm of 150mm benefit in terms of insulation.
The solution, should you intend to install flooring or already have flooring fitted and wish to retain it, is to install PIR board insulation between the joists and then lay your flooring over this. This method isn’t quite as effective as the wool as it leaves the ends of the wooden roof trusses uninsulated, which causes an element of cold bridging, where an uninsulated area meets with a cold space. Again there are solutions to this but these start to get expensive.
PIR & PHENOLIC INSULATION
PIR & phenolic insulation offers around twice the benefit of wool insulation products, so 150mm of PIR board = 300mm of wool (This is a slight generalisation as it does depend on the exact performance of both the wool and the PIR board but is the manner in which an EPC assessor would judge your insulation thicknesses)
There is also the cost to consider, PIR and phenolic foams are more expensive than wool products and the fitting takes longer as well.
An alternative to this is to have an area laid aside as storage by raising the loft floor up on stilts to allow 300mm of wool insulation to be laid and then chipboard is installed on top of the stilts, leaving insulation below. This method is only really suitable when you are intending to use the area as light storage and its not designed to be walked over so couldn’t be used to cover a whole loft.
VENTILATION ASSESSMENT
When carrying out any loft insulation works we will assess they ventilation in your loft and let you know whether additional ventilation is recommended. This varies from loft to loft and depends on your exact roof type.
Sometimes additional roof vents or ridge vents have to be installed, this is especially important if you have a sealed roof, where no external air is ventilating it.
Approved EPC Energy Assessors
We can organise comprehensive energy efficiency audits, retrofit assessments and official energy performance certificates to residents across Scotland.
We also offer more general energy advice to those who need pointing in the right direction.
CALL US ON 01241 452254
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