Self-build 65% Mortgage
For energy-efficient self-build projects, borrow up to 65% on a repayment basis or 50% interest-only — or combine the two. And when your home achieves an energy performance rating of 88+, you’ll be rewarded with our C-Change discount.
Your home may be repossessed if you do not keep up repayments on your mortgage
Heat Pump Cashback
Thinking about undertaking an energy-efficient self-build project or upgrading your home’s heating system? If you’re planning to install an air or ground source heat pump, you can claim for a £500 or £1000 cashback when you apply for a new mortgage at Ecology.
We offer a cashback for eligible residential mortgage applications for projects that include the installation of a heat pump. If you qualify, you can claim:
- £500 cashback for when you install an air source heat pump.
- £1,000 cashback for when you install a ground source heat pump.
To be eligible:
- Make sure that your installer is MCS accredited
- This offer applies to our self-build, renovation, conversion and shared ownership mortgages
- Your property must have existing loft and cavity wall insulation.
How to obtain the cashback
The process is simple and part of the mortgage process.
- When speaking to your appointed mortgage broker or one of our mortgage advisors, they will check your eligibility for the cashback.
- The cashback value and installers accreditation requirements and how to claim will be shown in your personalised illustration and any Offer of Loan.
- The cashback is payable within 18 months of completing your mortgage (i.e. when you receive your first stage release/advance) and with the production of an MCS installer certificate.
- The cashback will be paid when we receive a completion certificate confirming that the heat pump has been installed by an approved installer. If you qualify, your cashback will be paid into the bank account you use to make your monthly mortgage payments.
Other important information
Ecology is not responsible for ensuring the quality of the work carried out and the costs provided. You should carry out your own checks to ensure the costs and the supplier is suitable. If you find that you are not happy with the work carried out, you should speak to your supplier in the first instance. If the work carried out is covered under a scheme provider you should also contact the appropriate provider.
An example of a scheme provider is the Microgeneration Certificate Scheme (MCS) that are the standards and quality assurance organisation for renewable heat technologies such as solar thermal, air/ground source heat pumps and biomass boilers.
C-Change: Energy Efficiency Rewarded
We reward energy efficiency with our C-Change discount—because building a better future should benefit you too. Improve your property’s energy rating and you’ll not only cut energy bills and reduce your carbon footprint, but you could also secure a lower mortgage rate.
94% of our residential mortgage customers qualify for C-Change. It’s our way of saying thank you for making a positive change
How it works:
Take out your mortgage with Ecology
Build your new home or upgrade an existing property
Share your revised energy rating—we’ll calculate your discounted rate
Mortgage Calculator
Work out how much you could borrow and compare monthly payments.
Self-build FAQs
If you’re planning to build an energy-efficient, self-build property, we’re here to help.
At Ecology, we’re not put off by the construction type; we’ll support many types of construction techniques including those using non-standard materials and modern methods of construction. If we can see your self-build will be energy efficient using sustainable and where possible, locally sourced materials, we’ll consider lending.
We’ll lend on:
- Timber frame and timber clad
- Non-traditional such as straw bale, rammed earth, cob
- Modern Methods of construction built off-site
- Structurally insulated panels
- Insulated concrete forms
- Builds that contain renewables such as photovoltaics, solar thermal, heat pumps, etc.
Our mortgages are available in the UK (England, Scotland, Wales and Northern Ireland).
We’ll lend to support the purchase of the plot and the costs of your self-build project.
Outline planning permission needs to be in place to apply for the mortgage and detailed planning needs to be granted before any mortgage funds are released.
Normally, we’ll release up to 65% of the plot purchase price or value of the property if you already own the land and subsequently, the money required to cover the build costs. As you continue with your build, staged payments of up to 65% of your increased property value as the build progresses will be released – this will help you keep tabs on your budget and planning.
This type of mortgage may be suitable if you are able to make a 35% deposit for your plot and further funds to commence the early stages of the build. We normally recommend 20% of your total build budget as a good starting point to begin your self-build project.
Once your self-build is complete and you achieve the appropriate energy certificate, we can lower your interest rate through our C-Change discounts.
As a building society with a unique mission to build a greener society, we lend on projects and properties that support our aims through their reduced impact on our environment. Making your home energy efficient is a major way you can support tackling climate change – while saving on your energy bills.
We reward borrowers whose properties are energy efficient (therefore have lower carbon emissions) with our C-Change Discounts off our Variable Rate which helps them save money on their mortgage. We call our discounts ‘C-Change discounts’ simply because we’re aiming to make a ‘sea-change’ of difference to our climate with each property or project we fund.
The level of our C-Change sustainable homes or C-Change retrofit discount that applies is based on the Energy Standard rating achieved on the self-build, off-site build, renovation or conversion when the work is completed. Our C-Change energy improvements discount is based on the qualifying energy measures being installed. The discount is applied from the date we receive evidence that the work has been completed and if applicable the Energy Standard rating required has been achieved.
Do I need to provide planning permission for my self-build?
Yes. We need at least outline planning permission to start the application process and detailed planning permission before the mortgage is released.
What information do I need to progress a mortgage application?
You’ll need to have a specific plot and build in mind which needs to be supported by detailed plans, including a breakdown of material and labour costs and an indication of the energy standard you are building to. We’re currently focusing on self-build properties that are aiming for Passivhaus or EPC B (SAP rating 88+) or above.
What deposit do I need for my self-build?
You need a 20% minimum deposit to buy the land and a further 15% – 20% of total build costs to start your build.
Do I still need a deposit for my self-build if I already own the land and have planning permission?
No, you don’t always need a deposit; we can lend based on the value of your land to start the build, providing you already own the land and it’s mortgage-free. Also, if you need us to, we can help you repay any outstanding finance on the land.
Do you lend on buying the plot/land only?
We don’t just lend on a plot/land purchase. Any project we support needs to show planning details of the proposed build with an indication of the energy standard you are building to, and how the build costs are expected to be funded with savings and mortgage finance.
How long do I have to complete the build?
Subject to planning constraints, we allow a maximum of 2 years for you to complete the self-build, although we encourage you to complete earlier to benefit from our C-Change sustainable homes discount which is applied to our Standard Variable Rate from the date we receive evidence that both the work has been completed and the Energy Standard rating required has been achieved.
Do you offer stage payments for a self-build?
Yes, although the Ecology self-build mortgage does not release payments at set construction milestone stages (e.g. foundation, wall plate etc.). We release funds as and when the build progresses and release up to a percentage of the increased value of the property.
Can I have interest-only during the build phase?
We offer an interest-only mortgage only when you have a qualifying repayment vehicle to support this for example an established ISA, endowment policies or Pension Plan.
Does Ecology require a particular build warranty on completion of my self-build?
A build warranty is not a mandatory lending requirement of our mortgage and we are happy with a Building Regulation Completion Certificate. However, if you wish to take out a build warranty for the completion of the property then this is acceptable to the Society.
Does the self-build property have to be my main residence?
Yes, although we do offer a buy to let mortgage. Please bear in mind that the property can’t be a second or holiday home or classed as mobile planning.
Do you do mortgages for property renovations or conversions that are eco-friendly?
Yes, we do mortgages for other types of projects. Find details on what we lend on for conversions and renovations.
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