CalculatorFree tool
Loft insulation cost per m², built up properly
Start from the benchmark — published wages, a real gang, the costs on top of wages most people forget — then move anything you disagree with. The whole sum stays on the page.
The working
- 2 × labourer at £13.18
- £26.36
- Gang wage, per hour
- £26.36
- + 35% on top of wages
- £35.59
- × 8 hours on the tools
- £284.69 a day
- Roll between and over100mm between joists, 200mm over£284.69 ÷ 80 m² × 1.20 = £4.27/m²
Benchmark
£4.27/m² labour
CIJC rates · labourer £13.18/hr · gang of 2 · 35% on top · overheads and profit 20%
Materials, scaffold and supervision are not included in this rate.
What’s in this?
- Employer's National Insurance — 15% above £5,000 a year
- Holiday pay — 12.07%
- Pension, auto-enrolment minimum — 3%
- CITB levy — 0.35% of payroll
- Sick pay, training and employer's liability insurance — the remainder
- At 0% this is a CIS subcontractor's labour price — National Insurance, holiday and pension are then theirs to carry, not the job's.
The location range is authored, not measured — our tender data says what was bought where, not what labour costs there.
Price a whole job with this ratePut in the job size and your lump sums — scaffold, plant, skip — and get the job total.
The minimum starts at a day of the gang, priced — £341.63 — because travel, unloading and setting up make a day the honest floor. Type your own, or 0 for none.
Put a job size in and the total appears here.
The loft you are working in decides everything
80 m² a day for two is realistic in a clear, well-lit loft with a decent hatch and room to stand. Very few lofts are that. Trussed roofs with W-bracing every 600mm mean working on your knees and passing rolls through gaps; a loft full of stored belongings is a clearing job before it is an insulating one.
Nothing about that is visible in a floor area, which is exactly why the output is a control. You have put your head through the hatch; the calculator has not.
Two layers, laid in two directions
The normal specification is one layer between the joists and a second layer laid across them at right angles, so the second covers the cold bridge the joists create. That is two passes over the same area and it is what the benchmark assumes.
A top-up over existing insulation is one pass and quicker. If the loft already has a reasonable first layer, turn the output up accordingly rather than pricing a full installation.
The details that cannot be skipped
- Eaves ventilation. Insulation stuffed into the eaves blocks the airflow the roof needs, and a roof that cannot breathe gets condensation. Keeping the ventilation path clear is part of the job.
- Downlights and cabling. Insulation laid over non-fire-rated downlights is a genuine fire risk, and covering cable runs affects their current rating. Both need working around.
- Water tanks and pipes. Insulate above and around them, never underneath — a tank in a now-cold loft with no insulation over it is a burst pipe waiting for January.
- The hatch itself. An uninsulated, unsealed hatch undoes a surprising amount of the work.
What is not in the rate
Clearing the loft, boarding it out, or raising the boarding on legs so insulation can go to full depth underneath are all separate work. So is anything the survey turns up — a felt that has perished, or joists that will not take a boarded floor.
The insulation itself is a material. This card prices the labour to get it laid properly in the loft you have actually looked at.
Questions people ask
How long does it take to insulate a loft?
Around 80 m² a day for two people laying two layers in a clear, accessible loft. A cluttered loft, a trussed roof with restricted movement, poor lighting or a small hatch will all reduce that considerably — the condition of the loft matters far more than its floor area.
Should loft insulation be laid in one layer or two?
Two. The first goes between the joists and the second across them at right angles, which covers the cold bridge the joists would otherwise create. That is two passes over the same area, which is what the benchmark output assumes. Topping up existing insulation is one pass and quicker.
Why must insulation not be pushed into the eaves?
Because it blocks the ventilation path the roof needs, and a roof that cannot breathe gets condensation and eventually rot. Keeping a clear air path at the eaves is part of doing the job properly, and it is one of the commonest faults found in poorly installed insulation.
Can you insulate over downlights and cables?
Not without care. Covering downlights that are not fire-rated and insulation-compatible is a fire risk, and burying cable runs affects their current-carrying capacity. Both need to be worked around, which is part of why a real loft takes longer than its area suggests.
Does the price include boarding the loft?
No. Boarding, or raising boarding on legs so the insulation can reach full depth underneath, is separate work — as is clearing a loft full of stored belongings before anything can start. The insulation itself is a material, outside every rate on this site.
Where these figures come from
The wages are the national minimums agreed between employers and unions, republished each July. The costs on top of them are the statutory ones every employer actually pays. The outputs — how much a gang gets through in a day — are blended from published estimating guidance, and they are the part worth arguing with, which is why every one is a control you can move.
Other trades
- Bricklaying£35.68/m²
- Blockwork£23.84/m²
- Plastering£8.50/m²
- Rendering£38.34/m²
- Floor screed£2.83/m²
- Concreting£7.92/m²
- Tiling£17.71/m²
- Roofing£32.80/m²
- Block paving£25.56/m²
- Tarmac driveways£15.34/m²
- Resin driveways£16.61/m²
- Painting£14.17/m²
- Stud walls£17.71/m²
- Patios£31.95/m²
- Repointing£26.57/m²
- Plasterboarding£12.39/m²
- Decking£31.88/m²
- Fencing£25.56/m²
- Turfing£3.42/m²
- Coving£7.08/m²
- External wall insulation£38.34/m²
- Soft strip£8.54/m²
- Hand excavation£85.41/m²
- Shuttering£8.50/m²
- Mesh and rebar£2.56/m²
Pricing a job like these?
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