How to Budget For Your House Build and Spot Hidden Costs

The first expense is finding and buying the right plot. You can get an idea of land costs in your area with a bit of research and by speaking to local estate agents. Concentrate on just a few areas where you would like to put down roots. The wider the radius you draw, the more work you'll have visiting sites, meeting landowners and making decisions. Our journal, 8 Ways to Find Plots for Sale in Scotland will help you focus your efforts. You'll also need to factor in legal fees and taxes.

If you're building a bespoke home, a portion of your overall budget will need to cover hiring professionals like an architect, planning consultant and quantity surveyor. For context, Coldwells Build offers these services in-house as part of our Passivhaus range.

Consider where you'll live while your home is being built. Options include staying on-site in a caravan (which you may need to buy) or renting accommodation elsewhere. Both come with costs that should be included in your budget.

If you're building a bespoke home, set aside a contingency fund of 15-20% for unexpected expenses. A typical allowance is 15-20%, but consider your options carefully, what would you do if more funds were needed?

If you're building a Coldwells Build Passivhaus, a smaller contingency is sufficient. Our Passivhaus homes use a repeatable building system with pre-designed, prefabricated components. This means we know exactly how much material is needed, there's less waste and fewer variables that could lead to unexpected costs.

Once you've calculated all the costs outlined above, subtract them from your overall budget. The remaining amount is your construction budget. This is what you have available to actually build your home.

The location of your building plot can impact the overall project cost, especially if you're in remote areas like Scottish islands. In places like these, tradespeople may not be readily available, meaning they have to travel long distances to reach your site. This adds to the costs due to accommodation and travel expenses.

While it might be your dream location, if your budget doesn’t align with the realities of building there, you may need to reconsider your plans or look at increasing your budget.

Sloped sites are notorious budget busters, often demanding a split-level home, or extra digging, filling and levelling. It’s worth getting a topographical survey to make informed decisions on house position, access and the amount of groundworks required. 

The biggest cost uncertainties often lie beneath the surface of your plot. Extremely boggy or rocky ground could bump up costs. A boggy site could lead to drainage issues and may require deeper excavation and filling with imported hardcore. Larger rocks will need breaking up and any surplus removed from site. 

If you’ve found a site you want to buy, make sure to include a condition in your offer that lets you assess the ground conditions before finalising the purchase. This way, if the conditions are unsuitable for development, you'll have the option to withdraw from the purchase or renegotiate the price.

Ensure your plot has suitable access for vehicles and construction equipment. For example, if you're building a Coldwells Build Passivhaus, our installation requires a large crane to lift and position prefabricated panels—a steep or narrow track could prevent this.

Be cautious of plots that seem affordable but require a long access road. A site that needs a £40,000 access road can quickly erode any savings from a lower purchase price.

If you're building a Coldwells Build Passivhaus, we can provide a quote for creating access roads and clearing the site as part of your project

The availability of services like water, electricity and telecoms/broadband can affect the cost of developing a building plot. If your chosen site isn’t already hooked up to these services, it will cost extra to extend existing connections or install new ones. In rural areas, you might need to invest in a private septic tank or treatment plant if you can't connect to a mains sewerage system. If you’re building a Coldwells Build Passivhaus, we’ll obtain quotes from utility companies for service connections.

If you’ve bought an existing building, will it need to be demolished before your new home can be built? If so, this will need to be factored into the cost, along with skip hire and removing waste from site. If asbestos is present, a specialist contractor will be required to remove this safely. Similarly, if you're building on land previously used for agriculture or industry, there may be contaminated ground. This requires safely removing and disposing of the contaminated soil.

Building a bespoke home offers complete creative freedom, but it's also complex and time-intensive. From making countless design choices, material selections and layout decisions, it requires significant commitment and involvement.

If you're looking for a more streamlined approach, a pre-designed prefabricated home from our Coldwells Build Passivhaus range offers an alternative route. These homes are constructed off-site and come with predetermined specifications, which can save both time and money. You'll avoid the costs associated with custom design work while still achieving a high-performance, energy-efficient home.

You don't have to finish everything at once. Consider phasing your project to spread out costs. For example, you could add the garage later or start with simple landscaping and add more features over time. You can also plan for future upgrades, like solar panels, by installing the necessary wiring now. This approach allows you to move into your home sooner, while making improvements gradually as your budget permits.

One of the most important ways to control costs is to finalise your design before construction begins and stick to it. Making changes on site can be expensive, especially if they require altering or undoing completed work.

While it may cost around 4-8% more initially to build a Passivhaus, the long-term financial benefits far outweigh this upfront investment.

Passivhaus homes are designed to be extremely energy-efficient, which translates to significantly lower heating bills year after year. Beyond energy costs, Passivhaus homes also require less maintenance. The superior build quality, airtight construction and high-performance components mean fewer issues with damp, mould, or heat loss, common problems in standard builds that can be costly to remedy.

There's also the consideration of future-proofing. With increasingly stringent energy efficiency regulations, a Passivhaus is already compliant with standards that other homes will need to meet through expensive retrofits. You're essentially building to tomorrow's standards today.