Mortgage Budget Planner
At a glance: Use this planner to build a realistic self-build budget: break costs into plot/acquisition, build, professional & statutory fees, access/servicing, and add a sensible contingency (often 5–10%). Track a running total, estimate the mortgage you’ll need, and sense-check cashflow against stage payments. If in doubt, speak to a specialist broker (e.g., BuildStore or The Lending Channel) and consider an eco-focused lender (e.g., Ecology).
Common Questions
What is this planner for?
It helps you structure a total self-build budget, see where the money goes, and understand your likely mortgage requirement and cashflow before you commit.
How should I use it?
Enter costs under each heading: acquisition, build, professional/statutory, and servicing. Add contingency and allowances (landscaping, furniture, VAT). Then enter your own cash to see the estimated mortgage requirement.
What costs should I include?
Typical headings: land, legal, stamp duty, searches; kit/structure, groundworks, externals, M&E, fit-out, kitchens/bathrooms, prelims; architect/agent, engineer, planning, building control, surveys, warranty, insurance; access, water, power, drainage, telecoms.
How much contingency should I allow?
Normally 10–15% of pre-contingency costs. Use the higher end if your site has unknown ground conditions, steep access, or complex servicing.
How do stage payments affect my budget?
Lenders release funds at milestones (land, foundations, structure, watertight, completion). Align your costs and contractor payments with these stages to avoid cashflow gaps.
What’s the difference between valuation-based and cost-based stage payments?
Valuation-based: funds released after inspection of completed works. Cost-based: stage payments pre-agreed and released in advance (via specialist products), giving more predictable cashflow.
How do I estimate interest during the build?
As a guide, apply your APR to ~50% of the peak borrowing (the average drawn balance) multiplied by build months/12. The planner provides an indicative figure—your broker can give precise calculations.
Do I include VAT?
Add any non-reclaimable VAT in the VAT field. Many new build costs are zero-rated or reclaimable—check rules or ask your accountant. Always budget cautiously if unsure.
How much own cash or deposit do I need?
Varies by lender. Expect to put cash towards land and early works, plus a contingency. A broker can confirm deposit and maximum borrowing for your situation.
What documents support a budget and mortgage application?
Planning approval, drawings/specification, build programme, detailed cost plan or contract, surveys (GI/topo/percolation), warranty, site insurance, and details of your build system (SIP or CPS with BOPAS accreditation).
Are SIP and CPS homes mortgageable?
Yes. SIPs are widely accepted with a 10-year warranty. CPS homes are mortgageable and HebHomes’ system is BOPAS accredited, giving lenders added assurance.
How do I budget for access and servicing?
Obtain early quotes for access roads, water/boreholes, power, drainage (mains/septic/plant), and telecoms. These costs can make or break site viability.
What about budgeting in Ireland?
Irish self-build mortgages pay in stages. Lenders usually require full planning, a fixed-price contract or cost plan, and a recognised 10-year warranty (e.g., HomeBond, Global). Same principles apply: allow for servicing and contingency.
When should I involve a QS or broker?
Use this tool for a rough guide, then commission a QS for detailed costs and speak to a broker (BuildStore, The Lending Channel) early to align finance with your build.
What if my budget exceeds my borrowing capacity?
Options include reducing area/spec, phasing externals, reworking servicing, or switching to cost-based stage payments. A broker can advise on alternatives and products.
Common mistakes to avoid?
Underestimating ground or servicing costs, omitting professional fees, assuming valuation-based funds cover deposits, and setting contingency too low. Update your plan as quotes firm up.
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