Home renovations can transform your living space and add significant value to your property — but they can also be stressful and expensive if not planned properly. This guide covers costs, permissions, regulations, and strategies for getting the best return on your investment.
Renovation Costs
By Project Type
| Project | Typical Cost Range | Potential Value Added |
|---|---|---|
| New kitchen | £8,000–£25,000+ | 3–7% |
| New bathroom | £4,000–£12,000 | 3–5% |
| Loft conversion | £25,000–£60,000 | 10–20% |
| Single-storey extension | £25,000–£60,000 | 5–10% |
| Two-storey extension | £40,000–£100,000 | 10–15% |
| Garage conversion | £8,000–£20,000 | 5–10% |
| Full redecoration | £2,000–£8,000 | 2–5% |
| New windows | £4,000–£10,000 | 1–3% |
| Central heating upgrade | £3,000–£6,000 | 2–3% |
| Garden landscaping | £2,000–£15,000 | 1–5% |
Cost Per Square Metre
| Build Type | Cost (£/m²) |
|---|---|
| Basic renovation | £800–£1,200 |
| Standard extension | £1,500–£2,500 |
| High-spec extension | £2,500–£4,000 |
| Basement conversion | £2,000–£4,000 |
| Loft conversion | £1,200–£2,000 |
Location factor: London and South East +20–40%, South West and Midlands +5–10%, North -5–15%.
Planning Permission
Permitted Development (No Permission Needed)
Most of these do not require planning permission for houses (flats are different):
| Work | Permitted Development Limits |
|---|---|
| Rear extension (single storey) | 3m (semi/terrace) or 4m (detached) from rear wall |
| Side extension | Single storey, max 4m height, no more than half width |
| Loft conversion | Up to 40m³ (terrace/semi) or 50m³ (detached) |
| Outbuildings | Within limits (max 50% of garden, max height rules) |
| Internal alterations | Generally free (unless listed building) |
| Replacing windows | Like-for-like (must use FENSA installer) |
| Solar panels | Generally permitted (not above ridge line) |
When You DO Need Permission
- Exceeding permitted development limits
- Listed buildings (listed building consent needed even for internal work)
- Conservation areas (additional restrictions)
- Flats and maisonettes (most external changes)
- New dwellings (including converting a building into a dwelling)
- Changing use (residential to commercial)
Building Regulations
Even when planning permission is not needed, most significant work requires building regulations approval:
| Work | Building Regs Required? |
|---|---|
| Extensions | Yes |
| Loft conversions | Yes |
| Structural alterations (removing walls) | Yes |
| Electrical work (kitchens/bathrooms) | Yes (or use Part P registered electrician) |
| New bathroom/kitchen plumbing | Sometimes |
| Re-roofing | Sometimes |
| Replacing windows | Yes (use FENSA installer for self-certification) |
Planning Your Renovation
Step-by-Step
| Step | Action | Timeline |
|---|---|---|
| 1 | Set budget (add 15–20% contingency) | Month 1 |
| 2 | Check planning/building regs requirements | Month 1 |
| 3 | Get architects/designers involved (if needed) | Months 1–2 |
| 4 | Apply for planning permission (if needed) | Months 2–4 (8-week process) |
| 5 | Get at least 3 quotes from builders | Months 3–4 |
| 6 | Check builder credentials (references, insurance, qualifications) | Month 4 |
| 7 | Agree contract and payment terms | Month 4–5 |
| 8 | Building work begins | Month 5+ |
| 9 | Building control inspections (at key stages) | During build |
| 10 | Completion and sign-off | End |
Budgeting Tips
- Always have 15–20% contingency — unexpected issues are common (especially in older properties)
- Get detailed, itemised quotes (not estimates)
- Fix the price where possible — avoid day rates for large projects
- Stage payments — never pay everything upfront (10–20% deposit is reasonable, then payments at key milestones)
- Keep a record of all spending for future CGT calculations if the property is not your main residence
Choosing a Builder
What to Check
| Check | Why |
|---|---|
| References and portfolio | Proof of quality work |
| Insurance (public liability, employers') | Protection if something goes wrong |
| Trade body membership | Federation of Master Builders, TrustMark |
| Written contract | Clear terms for both parties |
| Fixed price vs estimate | Manage your budget |
| Realistic timeline | Over-promising is a red flag |
Red Flags
- Asking for full payment upfront
- No written contract or quote
- No evidence of previous work
- Cannot provide insurance details
- Significantly cheaper than other quotes (may cut corners)
- Pressure to start immediately
Tax Considerations
Main Residence
Improvements to your main home have no immediate tax impact. However:
- Capital improvements reduce CGT if you later sell and it becomes taxable
- Increased value may affect inheritance tax
Rental Property
For landlords:
- Repairs and maintenance are deductible against rental income
- Capital improvements (extension, new kitchen) are not deductible but reduce CGT when you sell
- The distinction: repairs restore existing condition; improvements enhance or change it
Financing Renovations
| Option | Typical Rate | Best For |
|---|---|---|
| Savings | 0% (no borrowing cost) | Any affordable project |
| Remortgage/further advance | 4–6% | Large projects (£20,000+) |
| Personal loan | 5–10% | Medium projects (£5,000–£25,000) |
| 0% credit card | 0% (for promotional period) | Small projects (under £5,000) |
| Specialist renovation mortgage | Varies | Major structural work |
For more on property costs and planning, see our conveyancing guide and mortgage calculator.
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Your home may be repossessed if you do not keep up repayments on your mortgage. PocketWise provides information and guidance — we do not offer financial advice. Seek independent mortgage advice before making decisions about borrowing.