Finding the right build plot can take time – and for good reason. How to know if a plot is worth buying and understanding all the potential pitfalls before you break ground will give you a true picture of a plot’s worth so your project doesn’t turn into a money pit.

1. What’s your total budget?

Before you decide how much to pay for a plot, get an idea of how much you’ll spend on the build. You’ll want to make sure the combined total isn’t higher than the estimated value of your finished house. A good start is to use Build It’s online cost calculator (www.self-build.co.uk/build-cost-calculator/) which provides prices for different house sizes, build methods, project management routes. Add to this fees, insurance, warranties, temporary living accommodation.

2. What’s the value of the finished house?

You’re not going to have a true answer until the house is complete. Get a feel for the market before you start by looking at comparable properties in the area on Rightmove (rightmove.co.uk). Talk to local estate agents too, and show them an outline design if you have one, or pictures of similar houses.

3. Is it a build plot?

Plots with planning permission to build a house will be more expensive than a piece of land without. The latter might look like a deal, but it isn’t a viable build plot and there’s no guarantee you’ll be able to get consent down the line. The council’s Local Plan will shed more light on the matter as you can see if it lies within the planning boundaries. Find out if there’s any planning history on the plot. The council’s online planning register provides details of current and expired consents, including refusals and the reasons why.

4. What’s the planning consent on the plot?

Although you’re not bound by the design that’s already received planning approval (as you can resubmit your application), don’t assume you can build bigger in the hope of maxing out on the value of the finished house. Conditions may state that you can only build on the agreed footprint – perhaps with a 1.5 storey height restriction – and you’ll need a strong case to challenge this. It’s worth checking to see if permitted development rights are still in place for the opportunity to extend later on.

5. What could cause problems?

Have a look around. Is the site connected to services or will they need to be installed or diverted?  Are there an obvious access points for vehicles to reach the site? Is there a flat build platform? Are there many trees, areas where bats might roost, a pond that could be a habitat for protected wildlife? Dig a little deeper and contact Land Registry to see if there are any covenants, rights of way, ransom strips that might restrict where or what you can build, but that can usually be resolved by a lawyer. Building control can provide information about the soil conditions.

6. Do you need a survey?

An ecological survey will reveal any measures you need to take to protect wildlife, such as fitting bat boxes to surrounding trees. While trees make a pleasing visual addition to a plot, if they’re too close to where you want to build then the roots could cause problems. A tree survey will highlight any issues and if any have a tree protection order (TPOs) on them; the council holds a list too. You may need a soil survey if ground conditions are potentially poor. This may flag instabilities, poor drainage, contamination as well as helping determine the foundation design.

7. Which foundations?

Strip foundations are the cheapest option, comprising of a strip of concrete and reinforced steel mesh in trenches of around one metre deep. Trench fill is as it says – concrete fills the trench. Piled foundations are driven deep into the ground, designed by a specialist engineer and the most expensive to construct.

8. What’s the gradient like?

Building on sloping sites is more complex when you compare it to a flat plot. Sloping sites could involve stepped foundations or deep piled foundations. Cutting and filling can be carried out to create a level plinth with retaining walls, a beam and block floor and additional drainage. As well as more time and cost, consider equipment hire and the knock-on effect for being on site for longer. Factors would include insurance and scaffolding payments. That said, this could be an opportunity to build a basement and an architecturally interesting design.

9. Is the price right?

Plotfinder (plotfinder.net), PlotSearch (buildstore.co.uk/find-land-or-a-project), Rightmove (rightmove.co.uk) will give you an indication of plot prices in the area. As a rule of thumb, a plot could be worth 25%-50% of the finished house, depending on the location and market factors. Don’t forget to include legal fees and stamp duty into the total spend. Other costs include surveys, engineered foundations design, a lawyer to resolve a covenant. You may also be able to highlight these problems to the seller as a way of negotiating the price down.

10. What should the contingency be?

You can’t plan for every eventuality – you might discover a sewer pipe, an underground stream, buried cables and so on. Plan in a contingency of at least 10% (15% is preferable).