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.

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

Start at the eaves and unroll the material towards the centre of the loft space, gently pressing the material into the space between two joists.

Ensure that a small gap is left at the eaves to allow ventilation.

At approximately half way across the loft cut the material carefully across it’s width with a sharp pair of scissors. By starting at the eaves it's easier to handle the roll of material in the centre of the space rather than trying to cut the correct lenght under the eaves.

Move to the opposite side of the loft and lay the second piece along the same joists towards the first piece.

Cut the second piece where it meets the first, and press the two lengths together to form a tight butt joint.

Repeat this procedure for the remaining joists spaces in the loft.

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, and you are unable to feed the insulation underneath, then its best to cut the material to fit along side making sure not to cover them.

Alternatively it may be easier to use loose-fill insulation if it is too awkward to fit rolled insulation around pipes etc. Again be sure not to cover the pipes or cables.

Loft hatch

The best way to insulate the top of the loft hatch is to place a suitable sized piece of 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.

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)