Why is it green?

Because about 25% of the heat generated escapes through the roof of an uninsulated house.

What’s involved?

Lay rolls of eco-friendly mineral wool between the joists, then another layer at right angles.  If you loft is boarded, or used as living accommodation, insulate the vertical walls and between and over the rafters with insulation and insulating board.  Joists raisers can be used to allow you to place insulation between ceilings and a boarded loft, if insulating between the rafters is not possible.

Did you know that loft insulation loses its performance over the years as it flattens?  To be its most effective, the insulation should be 270mm thick, so have a check and see if an upgrade is required.

Can I DIY?

You can lay mineral wool yourself between joists, but insulating rafters and walls and using insulating board is really a job for an expert.

How much does it cost?

From about £400 for a standard sized house.

Does it save you any money in the long run?

It will save, from uninsulated to an insulated loft, about £140 per year so you will recoup the cost in about 3 years

Can it be done in a Church?

Of course, especially if your church or chapel is built in the same way as a house with a ceiling and a void above before the roof.  If there is no ceiling, then it is harder, you can use insulation and insulating board, but this may be expensive simply to put up and may require internal scaffolding.

Other thoughts?

Firstly, if you’re doing this in a church or chapel, you may need to get consent for this work if you are making alterations beyond simply laying the mineral wool over joists, and, especially, if the building is a listed or in a conservation area.

Secondly, although mineral wool has no specific health risks, it can cause temporary itching, so wear long sleeves and gloves if you are susceptible. 

If you are working in a loft, beware of dust, ventilate the area if possible and use a mask to cover your nose and mouth.