Boarding a loft over insulation

Can you board straight onto loft joists?

No. By directly attaching boards to joists, you would have reduced insulation in between joists or you would squash insulation down where the boards are installed. In either case, insulation properties are reduced, and it has a lessening impact on loft insulation. 

You can board directly onto joists if you want to yourself but it would not pass a building control inspection because it would result in you not having the full 270mm depth of insulation required.

How to raise loft boards above insulation

This is carried out using loft zone supports. Here is a step by step guide instructing you the best way for this to be done.

1. Place the tri supports in position avoiding any obstructions.
2. Begin by setting out the rows the boards end on first then work into the intermediate rows as that position is not crucial and work around any obstructions you may come across.
3. Ensure that the rows of the tri supports are evenly spaced out.
4. Leave a gap at the eaves for ventilation.
5. Screw the plastic tri supports to the joists, each one fixed with two screws. 
6. Slide the beams onto the tri supports. Make sure that the slit in the beam is lining up with the hole in the tri support.
7. Now fit but do not screw the uni supports. Slide them into place under the beams and rotate them into a lock position. One support on every second cross beam is recommended.
8. Once all the tri supports are positioned screw them into pre drilled holes, then the same with the uni supports using one screw with each of these.
9. Finally you can apply the top up insulation and fix the boards.

Gap between insulation and loft boards

If using rigid insulation boards to insulate your loft there must be a gap between the roof covering and the insulation to allow air to circulate. This prevents any build-up of warm air that could lead to condensation. 

For this reason, a minimum gap of 50 mm must be left between the two to prevent it occurring.

Do you need building regs for loft boarding? 

Building Regulation approval is required to convert a loft or attic into a liveable space that will be walked on regularly such as a bedroom, office or study. This can be checked with your local council. If these approvals have not been received, the space will be considered unsafe.

If your loft board is being boarded to be converted into a storage space for light items then it will not require building regulations approval.

Do read about how loft insulation works? to know more about it.