New Build Mortgages: What Buyers Need to Know

Buying a new build property creates a set of mortgage timing and structural considerations that do not exist in the resale market. The developer's timeline - reservation, exchange, construction, and completion - drives the mortgage process rather than the standard conveyancing timeline.

Getting these elements right from the outset avoids the risk of losing a reservation deposit or missing completion deadlines. The sections below cover the points that catch new build buyers out most often.

Most new build developers require exchange of contracts within 28-42 days of reserving a property. For an off-plan purchase - where the property has not yet been built - this means exchanging on a contract for a property you may not see for 12 to 24 months. A non-refundable reservation fee (typically £500-£2,000) is paid on reservation and is lost if you do not exchange within the deadline.

Getting a mortgage offer within the exchange deadline is the central timing challenge of new build purchasing. Most new build lenders issue mortgage offers within ten to fourteen working days of a completed application, which is achievable within a typical 28-42 day reservation window - provided the application is submitted promptly and all documents are ready. Engaging a broker immediately on reservation, rather than spending time comparing options, is critical.

A standard mortgage offer is valid for six months. For off-plan new builds completing 12 to 24 months after exchange, the mortgage offer will expire before the property is ready. This means reapplying for a new mortgage at the point of practical completion - with the risk that rates have moved, the lender's criteria have changed, or the buyer's circumstances are different.

Specialist new build lenders offer extended validity periods - typically 9 to 12 months - that are specifically designed for off-plan purchases. Some lenders also have automatic extension policies for off-plan purchases where the build is delayed. When selecting a lender for an off-plan purchase, the offer validity terms and extension policy are as important as the headline rate.

Developers frequently offer buyers incentives to complete purchases: cashback payments, contributions to stamp duty or legal fees, free flooring packages, appliances, or upgraded specifications. These incentives are attractive - but they affect the price a mortgage lender uses to calculate LTV.

Most mortgage lenders require incentives to be disclosed and deduct their cash value from the purchase price when calculating LTV. An incentive worth 5% of the purchase price on a £300,000 new build reduces the lender's effective purchase price to £285,000. If the buyer has a £30,000 deposit, the LTV is calculated as £270,000 divided by £285,000 = 94.7% - higher than the 90% the buyer thought they had, with implications for rate and eligibility. Asking the developer for the incentive disclosure before finalising your deposit calculation avoids this surprise.

New build flats are subject to stricter LTV limits than new build houses across much of the mortgage market. Many standard lenders cap new build flat LTV at 75%, compared to 95% for new build houses.

A buyer purchasing a new build flat with a 10% deposit (90% LTV) will find their options very limited. Increasing the deposit to 25% opens the full specialist new build lender panel and dramatically improves rates. For buyers with only 10-15% available, a new build house (where 95% LTV products exist) is more mortgage-accessible than a new build flat.

Shared Ownership allows buyers to purchase a share of a new build property - typically 25-75% - paying a mortgage on their share and rent to the housing association on the remaining share. The mortgage is only on the share purchased, making the monthly payment considerably lower than purchasing the full property. Shared Ownership mortgages are a specialist product with a dedicated lender panel (not all standard mortgage lenders offer Shared Ownership products). LTV is calculated on the share purchased, not the full property value.

Staircasing - buying additional shares over time to increase your ownership percentage - can be funded by further Shared Ownership mortgage advances or by remortgaging to release the funds. The process of staircasing is administratively simple but requires the housing association's cooperation and the lender's consent.