Is boarding over loft insulation a DIY job?

Boarding over loft insulation can be DIY’d – it isn’t complicated but it will be physically hard work. It is recommended that you have at least 270mm of loft insulation but going for bit more can be convenient.

Boarding over loft insulation

Boarding over loft insulation – add more joists at right angles to the existing ones then roll out additional layer of insulation inbetween

We used 100mm thick sheeps’ wool insulation in a space covering 55m². The original 200mm layer of mineral wool was left in place. 100mm x 47mm wooden joists (from Wickes) were then secured at right angles to the existing load-bearing ceiling joists. We used small roofing “L” brackets with screws to secure them into place. (Use screws not nails so as to allow easier disassembly.)

These new over-joists were spaced so that the sheeps’ wool roll would fit neatly between them. After rolling out the first layer we then proceeded to apply another layer of over-joists at right-angle to the previous layer. Then sheeps’ wool insulation was laid between these joists. This was then covered in regular attic boarding from a DIY store.

Let the eaves breathe

We do not have enclosed eaves so we positioned insulation so as to allow airflow via the eaves. We did not apply boarding right up to the edges of the attic preferring to have unboarded strips all round for access, reduced cost & weight. Having a free flow of air above your insulation will quickly dry up any moisture which might otherwise result in damp (note the unboarded eaves to the left and right of the photo below).

Tools you’ll need

Boarding over loft insulation – electrical wiring must be laid on top of the insulation but under the boards – mark up its position for future reference

This DIY job requires a good wood saw, electric drill (to pre-drill screw holes for the brackets), electric screwdriver (really helps) and a way of counter-sinking the screw holes for the boards. We also added a new loft hatch which had a 100mm plug of polystyrene with a good airtight seal at the edges. We re-used the loft ladder that was already fitted, but had to add good electric lighting before work started.

Electrical wiring for the lighting circuit must be laid over top of the insulation but under the boards. We suggest using a black permanent marker to draw their position and purpose over top of the boards for reference later (the same goes for water piping & stop-cocks concealed by the boards).

Pros of DIY loft boarding

• We looked to get builders in to do this but couldn’t find one
• If you could find a builder it would cost an awful lot more
• You don’t need much more than basic skills with drill and screwdriver to do this
• It gives you 300mm of loft insulation and then all the loft storage you could want
• If you wish to install solar panels later (or if builders need to get to your attic) the flooring grants access

Cons of DIY loft boarding

• We did this job in summer, maybe not the best choice. You will need to be physically fit, attics can be cramped, uncomfortable, hot and dirty. Be prepared to hit your head a lot. Wear a boiler suit & dust mask – protect your lungs!
• You need good lighting so this must be mains-powered and installed first. Doing this job in poor light or with a torch in your mouth is not going to get you far and isn’t safe. You will need both hands to use power-tools.
• It will take time for one person to do. Our example was a one-man job typically done after work for a couple of hours each evening. It took nearly two months to complete. A long time to be on your hands and knees! Knee-pads a must.
• Take care of your safety. The ceiling plaster-board will not take your weight so you will need to be using boards (straddling the joists) to stand on. Do NOT cut through any load bearing structure!

Conclusion

This was the most time consuming and awkward task we undertook during retrofit. It was also the most satisfying because of it. It was NOT technically hard. It saved us a lot of money and (at the time) seemed the only way to get the job done the way we wanted it. We were also lucky that we have quite a vertically spacious loft space – keep in mind that an extra 200mm of insulation is height lost inside the attic.

Our project took a long time because we had inset ceiling lights that had to be boxed in and made airtight so as to prevent air leakage. Total cost of Sheep’s Wool = £999, attic lighting = £55 (another DIY job), wood/tools = £618.

© Mark Brown July 2012

Further Information:
Full details of this project are available at Post Carbon Living. There are commercially available systems now such as LoftZone StoreFloor. You can see the results of this loft boarding project at Mark Brown’s SuperHome at Open Days in September or by appointment. Mark is a member of Transition Town High Wycombe.

See Also:
Best insulation
Cavity wall insulation work

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