Construction financing: mortgage, Help to Buy and grants
Financing is the backbone of your self-build project. Standard mortgage, Help to Buy, local authority grants, employer-assisted schemes… There are many levers available to fund your home, provided you know about them and activate them in the right order. This article walks you through every option, with up-to-date conditions and caps for 2026.
The self-build mortgage: how it works
A mortgage for building works differently from one for buying an existing property. The key difference: staged fund releases.
Staged drawdowns
The lender does not release the full loan in one go. Funds are drawn down in line with build progress:
| Build stage | % released | Trigger |
|---|---|---|
| Land purchase | 100 % of land loan | At completion (solicitor) |
| Site start | 5–15 % | On presentation of planning permission |
| Foundations complete | 25 % | Contractor certificate or photos |
| Walls + roof (watertight) | 40–45 % | Progress inspection |
| Weathertight (windows fitted) | 60–65 % | Progress inspection |
| Second-fix trades | 80–85 % | Invoices from contractors |
| Completion + handover | 95–100 % | Snagging sign-off |
⚠️ Warning — In self-build, staged releases are more complicated because there is no main contractor providing certificates. Some lenders refuse self-build mortgages outright. Others will accept photos and material invoices as evidence. Raise this point at your very first meeting with any lender.
Stage payments / interim interest
During the build, you do not yet repay capital — only interim interest on the amounts already released, plus your mortgage protection insurance. This is a hidden cost that must be budgeted:
| Amount released | Rate (3.5 %) | Monthly interest |
|---|---|---|
| £50,000 | 3.5 % | ~£146/month |
| £100,000 | 3.5 % | ~£292/month |
| £150,000 | 3.5 % | ~£438/month |
| £200,000 | 3.5 % | ~£583/month |
Over a 12-month build, interim interest can add up to £3,000–£7,000 depending on the loan amount and rate.
💡 Tip — Some lenders offer a full payment holiday: you pay nothing during the build (neither capital nor interest). Interest is then rolled up and added to the loan. It eases cash flow but costs more overall. Compare both options carefully.
Help to Buy and shared ownership in 2026
Help to Buy is the most powerful boost for first-time buyers in England. Combined with shared ownership schemes, it can significantly reduce your mortgage burden.
Eligibility criteria
To benefit from Help to Buy / shared ownership in 2026:
- First-time buyer: you must not have owned a residential property in the last 2 years.
- Primary residence: the property must be your main home for at least 6 years.
- Income caps: your household income must not exceed the thresholds set by Homes England (varies by region and household size).
2026 income thresholds (indicative)
| Household size | London | South East | Midlands | North / Wales |
|---|---|---|---|---|
| 1 | £90,000 | £80,000 | £70,000 | £60,000 |
| 2 | £90,000 | £80,000 | £70,000 | £60,000 |
| 3 | £90,000 | £80,000 | £70,000 | £60,000 |
| 4 | £90,000 | £80,000 | £70,000 | £60,000 |
| 5+ | £90,000 | £80,000 | £70,000 | £60,000 |
Loan or equity share amounts
Help to Buy equity loans cover up to 20 % of the total cost (40 % in London), within regional property value caps:
| Region | Property value cap (couple + 1 child) | Max equity loan (20 %) |
|---|---|---|
| London | £600,000 | £240,000 (40 %) |
| South East | £437,600 | £87,520 |
| East of England | £407,400 | £81,480 |
| South West | £349,000 | £69,800 |
| North / Midlands | £261,900 | £52,380 |
Repayment
The equity loan is interest-free for the first 5 years, then a fee of 1.75 % applies, rising annually with RPI + 1 %. During the interest-free period you only repay your main mortgage. This is the key benefit: lower monthly payments in the early years.
Best practice — Help to Buy is stackable with other schemes (standard mortgage, employer-assisted loan, Lifetime ISA). Always check your eligibility — it is effectively free money for the qualifying period.
Other grants and complementary loans
Employer-assisted schemes (ex-workplace loans)
If you work for an employer with more than 10 staff, some larger employers and housing associations offer:
- Amount: up to £25,000–£40,000
- Rate: subsidised (often 1–2 %)
- Term: up to 25 years
- Condition: purchase or build of your primary residence
Check your HR department or staff handbook — these schemes are often underused.
Lifetime ISA (LISA)
If you hold a Lifetime ISA:
| Product | Maximum bonus | Government top-up |
|---|---|---|
| LISA | £1,000/year | 25 % on up to £4,000/year |
| Help to Save | £1,200 | 50 % on savings (lower income) |
LISAs opened before age 40 attract a 25 % government bonus on contributions. The bonus can be used towards a first home purchase or self-build land.
Local authority and regional grants
Many councils and combined authorities offer construction-related assistance:
- Local councils: council tax exemptions during build (1–2 years), first-homes discounts
- County/combined authorities: grants for sustainable build, rural plot incentives
- Devolved governments: energy-efficiency grants (Wales, Scotland), eco-grants
💡 Tip — Contact your local Citizens Advice bureau or local authority housing team. They are free and they know every available grant in your area. The government’s own.homes.gov.uk portal also lists schemes by region.
Green mortgage / eco-grant
If you build to high energy-performance standards (EPC A or Passivhaus), some lenders offer:
- Green mortgage discount: 0.1–0.3 % off your rate
- Amount: up to £50,000 additional green lending
- Rate: at or below standard mortgage rate
- Eligible works: insulation, heat pump, solar PV
Financing a self-build: specific challenges
Self-build presents particular financing challenges:
Lenders that accept self-build
Not all lenders finance self-build. Here is the current landscape:
| Lender type | Full self-build | Partial self-build |
|---|---|---|
| Buildstore / Ecology BS | Yes | Yes |
| Bath Building Society | Yes | Yes |
| High street banks | Rare | Sometimes |
| Nationwide | No | Yes (select cases) |
| Online-only lenders | No | No |
| Specialist mortgage broker | Possible | Yes |
⚠️ Warning — In full self-build without a formal building contract, the lender takes on more risk. They will typically require a higher deposit (20–30 % rather than 10 %) and stronger security (first legal charge rather than guarantee).
Documents required
For a self-build mortgage, lenders will want:
- A detailed technical specification with schedules and materials list
- A line-by-line cost plan (use our total budget calculator)
- Contractor quotes for sub-contracted packages
- Granted planning permission
- Self-build warranty (e.g. NHBC Buildmark, Protek, Zurich) — often required to release funds
Mortgage broker or direct lender?
A mortgage broker is particularly useful for self-build because they know which lenders accept this type of application. Broker fees are typically paid by the lender (not by you), making it a free service for the borrower — though always confirm this upfront.
Optimising your financing plan
The ideal plan combines several sources to minimise total cost:
| Source | Amount | Rate | Monthly payment |
|---|---|---|---|
| Help to Buy equity loan | £80,000 | 0 % (5 yrs) | £0 (deferred 5 years) |
| Employer scheme | £25,000 | 1 % | ~£100/month |
| Main mortgage | £200,000 | 3.5 % | ~£1,000/month (25 yrs) |
| Personal deposit | £45,000 | — | — |
| Total | £350,000 | ~£1,100/month |
Without Help to Buy and employer scheme, the same project would cost ~£1,400/month. That is a saving of ~£300/month, or roughly £90,000 over 25 years in interest saved.
Key takeaways
Financing a self-build must be planned 6 months before breaking ground. Check your Help to Buy eligibility, consult a specialist mortgage broker, and explore local grants. Do not limit yourself to your existing bank — competition between lenders can save tens of thousands of pounds over the life of the loan.
Checklist: self-build financing
- Borrowing capacity calculated (debt-to-income ratio < 35–40 %)
- Personal deposit confirmed (10–20 % standard, 20–30 % for self-build)
- Help to Buy / shared ownership eligibility checked (income, region, first-time buyer)
- Employer-assisted scheme applied for (if employer > 10 staff)
- Lifetime ISA / Help to Save checked for government bonus
- Local grants identified (council, combined authority, devolved govt, Citizens Advice)
- Specialist self-build mortgage broker contacted
- Interim interest budgeted (£3,000–£7,000 over 12 months)
- Mortgage protection insurance compared (independent policy vs lender’s)
- Multi-source financing plan optimised