Remortgaging for home improvements

How a home-improvement release works

You remortgage at a higher loan amount, the new lender pays off the old one and releases the difference. The cash arrives in your account at completion and you draw it down as the build progresses. Some lenders release the funds in stages tied to a build schedule, especially on larger renovations.

Lenders like this purpose

Home improvement releases are well understood by lenders. The works usually add value to the property, which protects the lender, and the spend is one-off rather than ongoing. Most mainstream lenders accept the purpose without restrictive conditions, as long as the loan-to-value (LTV) works and the scope is realistic.

Sizing the borrow

Get a builder quote with VAT included, plus 10 to 15 percent contingency, plus professional fees (architect, structural engineer, planning, party wall). Borrow the realistic total, not the optimistic one. We have seen too many clients half-finish a build because the budget did not include contingency.

Worked example, a single-storey rear extension

Builder quote £65,000 plus VAT (£78,000). Architect and structural engineer £6,000. Planning fee and building control £1,500. Party wall surveyor £1,500. Contingency at 12% (£9,360). Realistic total around £96,000. Borrowing on a £90,000 figure leaves you £6,000 short on a typical project; we recommend rounding up to the £96,000 number. The post-build property value uplift on a typical extension is £75,000 to £110,000, so the equity position usually improves overall once the work completes.

Further advance versus full remortgage

If your existing lender offers a further advance at a competitive rate, it is often the cleanest route. No legal work, no new lender, your original mortgage continues. Compare the further advance rate against a full remortgage at your new total LTV before deciding. Sometimes the further advance wins. Often the full remortgage does. The deciding factor is usually how close to a fix-end-date you are; if you are 6 months out from the end of your existing fix, a full remortgage almost always wins because you align the further capital with a cheaper market rate on the whole loan.

Green mortgage discounts

If your improvements meaningfully raise the property EPC (Energy Performance Certificate) rating, several lenders offer green mortgage products with small rate or fee discounts. Solar, heat pumps, insulation upgrades and triple glazing are the qualifying works to watch. As an illustrative example only, discounts of around 0.05 to 0.20 percentage points or a fee waiver of £250 to £500 are sometimes available. Green mortgage eligibility criteria and incentives vary between lenders and may change over time. Modest, but worth picking up where it applies.

Stage-release lending on larger projects

For builds over £100,000, several specialist lenders release funds in tranches tied to a build schedule rather than as a single lump sum at completion. This means you only pay interest on funds drawn, not on funds sitting in the account. The arrangement is more administratively heavy and is usually only worth it on larger projects.

Common pitfalls we see

Borrowing the optimistic builder quote, not the realistic figure with VAT and contingency. Starting works before the funds release. Forgetting that planning permission and building control sign-off are both required for many extensions and that lenders may ask for evidence. Taking a personal loan to bridge between funds shortfall and works completion at high rates. We work the budget conversation up front so the build does not stall.