Prepare the loft

Clean and dust the gaps between joists, and check the ceiling below.

Seal any gaps in the ceiling, its easier to do this from above, and also seal around pipes/cables which run through ceiling. Either a purpose built sealant such as expanding foam, or screwed up pieces of newspaper with decorating filler over the top, are ideal for this purpose.

Prepare the joists

Any gaps between the joists under the eaves need to be sealed to keep the material in the loft space.

The simplest way to complete this is to screw lengths of plywood to the ends of the joists to stopper the ends of each joist gap. Alternatively insulation retaining products are available from most builders merchants.

The majority of ceilings joists are only 100mm – 150mm in height (4in – 6in), therefore the achieve the necessary minimum of 200mm (8in) of insulation the joists will need to be raised. This simply involves nailing appropriate sized strips of wood down the length of each joist.

Ventilation

The loft space must have adequate ventilation to ensure that condensation does not build up and create a damp problem. If you can see any daylight near the eaves or between any slates or tiles, then ventilation is probably not an issue. If not, then additional ventilation must be added.

A ventilation slot running the length of the eaves, approximately 10mm (3/8in) wide, is usually more than enough. If the eaves have a soffit, then soffit vents are a perfect solution.

• A soffit is the exposed underside of any overhead component of a building, such as an arch, balcony, beam, cornice, or lintel.

Laying procedure

Loose-fill insulation is simply poured into the spacing between the joists to the required depth.

To reach under the eaves use a garden hoe, or a similar ‘home made’ alternative using a broom handle.

Obstacles in the loft

Always feed insulation under electrical cables. Do this carefully to ensure that the cable is not stretched.

Also feed insulation under any roof members which go across the joists.

Do not insulate under any Cold Water tank, this must be insulated separately to avoid condensation build up.

If any pipes or electrical cables run between the joists, be sure not to cover them with material.

Loft hatch

The best way to insulate the top of the loft hatch is to place a suitable sized piece of rolled or matting insulation into a black bin liner, then affix this to the hatch. This ensures it fits correctly, does not come loose with movement, and is easy to handle every time you wish to use the loft space.

Alternatively carefully fill a black bin liner with loose-fill insulation and affix this to the top of the hatch – clearly this is not a desired method, more a last resort!

Ensure the hatch cover fits correctly and draught proof the edges to avoid heat loss around the hatch. It may need to catch or bolt to keep it tightly shut.

Further information and useful links

• Successfully damp proofing your home

• Find a Builders Merchants near you

• National Insulation Association
• Energy Savings Trust (est.org.uk)
• Cavity Insulation Guarantee Agency (ciga.co.uk)
• Party Wall Guidance (rics.org)
• Impact of the Party Wall Act 1996 (communities.gov.uk)