# Insulation Cost Calculator

> Estimate insulation costs for loft, walls, and floor. Compare DIY vs professional prices, material costs by type, and energy savings payback.

Canonical: https://renoquant.com/insulation-cost-calculator
Prices updated: 2026-03

## How Much Does Insulation Cost?

Understanding insulation costs helps you budget your project and choose the best option for your home. The total cost depends on the insulation type, the area to cover, whether you hire a professional, and the complexity of the installation.

### Material Cost by Insulation Type

| Insulation Type | Thermal Conductivity (W/mK) | Cost per m2 (100mm) | Cost per m2 (equivalent R-value) | Best For |
|----------------|---------------------------|--------------------|---------------------------------|---------|
| Glass mineral wool | 0.044 | EUR 3-5 | EUR 3-5 (baseline) | Lofts, stud walls |
| Rock mineral wool | 0.038 | EUR 5-8 | EUR 4-7 | Lofts, fire protection |
| PIR board (Celotex/Kingspan) | 0.022 | EUR 12-22 | EUR 6-11 | Walls, floors, flat roofs |
| Expanded polystyrene (EPS) | 0.034 | EUR 5-10 | EUR 4-8 | External wall insulation |
| Spray foam (open cell) | 0.038 | EUR 20-35 | EUR 17-30 | Lofts, awkward spaces |
| Spray foam (closed cell) | 0.025 | EUR 35-55 | EUR 18-28 | Walls, roofs, moisture barrier |
| Sheep wool | 0.038 | EUR 12-22 | EUR 10-19 | Eco-friendly lofts, stud walls |
| Cellulose (blown) | 0.040 | EUR 8-15 | EUR 7-13 | Loft top-up, cavity fill |

The "equivalent R-value" column shows what you would pay to achieve the same thermal resistance as 100mm of mineral wool using each material. This makes it easier to compare products with different thermal performance.

### DIY vs Professional Installation Costs

| Project | DIY Material Cost | Professional Cost (materials + labour) | Saving with DIY |
|---------|-------------------|---------------------------------------|-----------------|
| Loft insulation (50 m2, 270mm) | EUR 250-450 | EUR 600-1,200 | 50-65% |
| Loft top-up (50 m2, 170mm layer) | EUR 150-280 | EUR 400-800 | 55-65% |
| Cavity wall (80 m2) | Not DIY | EUR 1,200-2,800 | — |
| Internal wall insulation (40 m2) | EUR 600-1,200 | EUR 1,800-3,600 | 55-65% |
| External wall insulation (80 m2) | Not DIY | EUR 5,000-14,000 | — |
| Floor insulation (40 m2, from below) | EUR 300-600 | EUR 800-1,800 | 55-65% |
| Floor insulation (40 m2, PIR boards) | EUR 500-900 | EUR 1,200-2,400 | 55-60% |

Cavity wall and external wall insulation require certified professionals and specialist equipment — these are not suitable as DIY projects.

### Full Cost Breakdown: Loft Insulation (50 m2)

Here is a detailed budget for insulating a typical loft from scratch to the full 270mm depth:

| Item | Budget Option | Mid-Range Option | Premium Option |
|------|-------------|-----------------|---------------|
| Mineral wool 100mm (7 rolls) | EUR 175-245 | EUR 210-280 | — |
| Mineral wool 170mm (7 rolls) | EUR 210-315 | EUR 245-350 | — |
| Sheep wool 100mm + 170mm | — | — | EUR 500-900 |
| Loft hatch insulation kit | EUR 20-30 | EUR 25-35 | EUR 25-35 |
| Pipe lagging (20m) | EUR 15-30 | EUR 15-30 | EUR 15-30 |
| Tank jacket | EUR 15-25 | EUR 15-25 | EUR 15-25 |
| Eaves ventilation trays (20 pcs) | EUR 15-25 | EUR 15-25 | EUR 15-25 |
| Dust mask + gloves | EUR 10-15 | EUR 10-15 | EUR 10-15 |
| Insulation knife | EUR 8-12 | EUR 8-12 | EUR 8-12 |
| **Total DIY** | **EUR 468-697** | **EUR 543-772** | **EUR 588-1,042** |
| **Professional install** | **EUR 600-1,000** | **EUR 750-1,200** | **EUR 1,000-1,800** |

### Insulation Cost by Room Type

| Room / Area | Area (typical) | DIY Material Cost | Professional Cost |
|------------|---------------|-------------------|-------------------|
| Small loft (terrace) | 25 m2 | EUR 150-300 | EUR 350-700 |
| Medium loft (semi) | 40-50 m2 | EUR 250-500 | EUR 600-1,200 |
| Large loft (detached) | 70-100 m2 | EUR 400-800 | EUR 900-1,800 |
| One bedroom floor | 12-15 m2 | EUR 80-200 | EUR 250-500 |
| Whole ground floor | 40-60 m2 | EUR 300-700 | EUR 800-2,000 |
| One internal wall | 8-12 m2 | EUR 100-250 | EUR 300-600 |
| All external walls (cavity) | 80-120 m2 | Not DIY | EUR 1,200-3,500 |

### Energy Savings and Payback Period

Insulation reduces heating bills by preventing heat loss. The payback period depends on the installation cost and annual savings:

| Insulation Project | Installation Cost | Annual Saving | Payback Period | 10-Year Net Saving |
|-------------------|-------------------|---------------|----------------|---------------------|
| Loft (0mm to 270mm, DIY) | EUR 300-500 | EUR 250-350 | 1-1.5 years | EUR 2,000-3,000 |
| Loft (100mm to 270mm, DIY) | EUR 150-280 | EUR 100-180 | 1-2 years | EUR 750-1,500 |
| Cavity wall (professional) | EUR 1,200-2,800 | EUR 150-300 | 4-9 years | EUR 300-2,000 |
| Solid wall internal (professional) | EUR 4,000-8,000 | EUR 200-400 | 10-20 years | EUR -2,000-0 |
| Solid wall external (professional) | EUR 5,000-14,000 | EUR 250-450 | 11-30 years | EUR -8,500-500 |
| Floor insulation (DIY) | EUR 300-700 | EUR 50-100 | 3-7 years | EUR 200-700 |

Solid wall insulation has a long payback period on pure cost savings alone. However, it also improves comfort, reduces draughts, and increases property value — factors not captured in the payback calculation.

### Cost-Saving Tips

1. **Start with the loft** — It has the fastest payback and is the easiest DIY job. A single weekend can save you EUR 250+ per year.
2. **Check for grants first** — Government insulation schemes can cover 50-100% of the cost for eligible households. Apply before you buy materials.
3. **Buy in bulk** — Multi-packs of insulation rolls are 15-25% cheaper per m2 than buying individual rolls.
4. **Top up, do not replace** — If your existing loft insulation is dry and in good condition, just add a layer on top rather than removing and replacing it.
5. **Combine projects** — If you are already having building work done (new roof, extension, renovation), adding insulation at the same time is much cheaper than retrofitting later.
6. **Compare quotes** — Get at least three quotes for professional installation. Prices vary significantly between installers, especially for cavity and solid wall insulation.

### Professional Installation: What to Expect

| Cost Factor | Affects Price Because |
|------------|----------------------|
| Property type | Detached homes have more external wall area than terraces |
| Access difficulty | Lofts with limited headroom or no boarding take longer |
| Existing insulation | Removing old insulation adds EUR 3-8 per m2 |
| Cavity width | Narrow cavities need thinner (more expensive per R-value) insulation |
| Wall condition | Damp walls need treatment before insulation (EUR 500-2,000 extra) |
| Scaffold requirement | External wall insulation on 2+ storeys needs scaffolding (EUR 500-1,500) |
| Regional pricing | Labour costs vary 20-40% across different regions |

Always ask for a written quote that breaks down materials and labour separately. This lets you compare quotes on a like-for-like basis and understand exactly what you are paying for.

## Frequently Asked Questions

### How much does insulation cost per square metre?

Material costs range from EUR 3-5 per m2 for mineral wool rolls (loft) to EUR 15-30 per m2 for PIR board (walls/floors). Professional installation adds EUR 10-25 per m2 for lofts and EUR 25-60 per m2 for wall insulation. Spray foam is the most expensive at EUR 20-50 per m2 for materials alone.

### Is it cheaper to insulate yourself or hire a professional?

DIY loft insulation costs EUR 3-9 per m2 in materials only, while professional installation costs EUR 15-30 per m2 including materials. That makes DIY roughly 60-70% cheaper for loft insulation. However, cavity wall and solid wall insulation should always be done professionally as they require specialist equipment and incorrect installation can cause serious damp problems.

### How long does it take for insulation to pay for itself?

Loft insulation has the fastest payback at 1-2 years. Cavity wall insulation pays back in 3-5 years. Solid wall insulation takes 8-15 years to recoup due to the higher installation cost. Floor insulation typically pays back in 3-6 years. Energy prices affect payback — higher prices mean faster returns.

### Are there grants available for home insulation?

Many European countries offer insulation grants and subsidies. The UK has the ECO4 scheme and Great British Insulation Scheme covering loft and cavity wall insulation for eligible households. Ireland offers SEAI grants up to EUR 3,250 for wall insulation. France has MaPrimeRenov covering up to 90% of costs for low-income households. Check your national energy agency for current programmes.

### What is the most cost-effective type of insulation?

Mineral wool (glass wool or rock wool) offers the best value for money. It costs EUR 3-5 per m2 for 100mm thickness, is easy to install in lofts and stud walls, and provides good thermal and acoustic performance. PIR board costs more but is twice as effective per millimetre, making it the better choice where space is limited.

### How much does it cost to insulate a whole house?

Insulating a typical 3-bedroom semi-detached house costs EUR 500-1,500 for a full DIY loft insulation, EUR 1,500-3,500 for professional cavity wall insulation, and EUR 5,000-14,000 for external solid wall insulation. A complete package of loft, walls, and floor insulation typically totals EUR 3,000-8,000 professionally installed for a standard home.

---

Interactive version with calculator: https://renoquant.com/insulation-cost-calculator. Figures are estimates; final quotes vary by site conditions, materials, and region.