How To Insulate A Loft – Loft Insulation Tips


The job of laying loft insulation is not a difficult one and it provides very worthwhile savings in fuel costs.


Apart from clearing the loft of anything you have stored there, little preparation work is necessary. However, this is the time to tackle repairs you’ve been putting off — closing any roof tile gaps. For example. Which could later expand, let in water and cause a build up of damp in the insulation. Seal any holes where birds or vermin can enter, especially at eaves and gutters. But DO NOT cut off all ventilation because this can encourage dry rot.

how to insulate a loftCover ventilation gaps with a fine wire mesh to keep birds out.

Inspecting timbers for wood-worm is also worthwhile at this stage.

Access to joists will be difficult after the insulation is laid, and if there is any wood-worm present, any insulation must be removed to treat it.

For ease and safety, make a platform to work from by laying a number of boards across three or four ceiling joists, moving them as you go.

Insulation materials

There is a variety of loft insulation products. Prices vary so check to see which is the best buy locally.

Blanket: Made either of glass fibre or mineral wool. This comes in rolls wide enough to fit into the 350mm to 400mm spacing between joists.

Various thicknesses are avail-able: the thicker the material. The better the heat retaining properties. Regard 75mm as the absolute minimum although some firms are now making material 150mm thick.

To lay blanket insulation. You just place the roil between the joists and unroll it. Wear gloves. Goggles and a dust mask to prevent irritation. Be careful not to compress the material as you work. Cut at the end of one run and start again. Lay under pipes and wire for easy access to them later should you ever require it.

When you get to the eaves or other awkward areas. A long handled brush may help push the material in.

Don’t insulate beneath your cold water tank.

Put insulation on the loft, side of the trap door. Cut a piece of insulation to fit and cover it with polythene.

Quilt: This is wider than the rolls and in the same materials.

It’s intended to be draped over joists and because it traps a layer of air between itself and the ceiling below. It has better heat retaining qualities.

The disadvantage of quilt insulation is that it can cause access problems later and you will also need to make ‘walk-ways’ of boards screwed to joists above the quilt.

Foil: With a reflective face comes in quilt form for laying over joists. But used on its own it is not as effective as the other materials mentioned.

Loose fill: Some people find this the easiest insulating material of all to work with. You buy loose pellets or pieces — vermiculite or mineral fibre — by the bag and simply tip them straight into the spaces between the joists. 3. Aim for a depth of 100mm and. To get it level, make up a spreader from a piece of board.

Incidentally, if your joists are more widely spaced than normal you can use a combination of blanket and loose fill — use the loose material to fill the gap.

When working, some of the materials can cause irritation to skin, nose and eyes. So be safe while you work. Wear mask, gloves and goggles.

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