Self build budget spreadsheet: is there something better?
Short answer
A spreadsheet is a perfectly good way to budget a self build, as long as it has a row per line, grouped by stage, and columns for budget, quoted, committed, paid, projected cost and VAT. Spreadsheets start to break down when two people edit separate copies, quotes don’t match your stages, VAT gets mixed in and out, and you need answers on site from your phone. That is when a dedicated budgeting app earns its keep.
Spreadsheets are a good place to start
They are free, flexible and familiar. You can shape them to your project, and nobody can take your data away. Many self builders start there, and so did we: Simon built ours, and it carried us through the early estimate and the first round of quotes.
If you want a head start, download our free template.
What a good self build spreadsheet needs
Rows grouped by stage. Use the stages UK builds follow: preliminaries, groundworks and foundations, superstructure, roof, windows and doors, first fix, plastering, second fix, kitchen and bathrooms, finishes, external works, fees and other costs. Then a separate contingency row.
These columns for every row:
| Column | What it holds |
|---|---|
| Budget | What you planned to spend on this line |
| Quoted | The best quote you have, for comparison |
| Committed | Accepted quotes and orders you’re now on the hook for |
| Paid | What has actually left your account |
| Projected | Your best estimate of the final cost (see below) |
| Variance | Projected minus budget |
| Net, VAT, gross | The VAT split, so you know what you can reclaim |
A projected cost formula. The simplest rule: projected is the higher of committed and paid, or the budget if nothing is committed yet. That single column tells you where you will finish.
A clear VAT basis. Write at the top whether figures include VAT, and keep a separate VAT column on your payments log.
A payments log on its own tab. One row per invoice: date, supplier, line, net, VAT, gross, and where the invoice is saved.
A contingency tracker. Starting amount, every draw with a reason, and what is left.
Where spreadsheets break down
Versions between partners. One of you updates the copy on the laptop, the other the one on their phone. A week later neither is right. Shared online spreadsheets help, but formulas still get overwritten.
Quotes that don’t match your stages. A builder’s single figure for “shell” has to be split by hand across several rows, and it’s easy to double count or miss part of it.
VAT in and out. Some cells include VAT and some don’t, and nobody remembers which. Totals end up out by a fifth.
No projected cost. Most home-made budgets have budget and paid but nothing in between, so they show where you’ve been, not where you’re heading.
On site, on a phone. Big spreadsheets are hard to read and harder to edit on a small screen, which is where the decisions often get made.
Formula errors. A sum range that misses a row, a pasted value over a formula. One wrong cell can hide thousands.
Documents live somewhere else. The quote PDFs and invoices end up in email, a folder and a pile on the kitchen table, so checking a figure means a search.
Spreadsheet or app?
| Spreadsheet | Budgeting app | |
|---|---|---|
| Cost | Free | Usually a monthly fee |
| Flexibility | Total, you build it | Works the way the app is designed |
| Set-up time | Hours to build well | Minutes to start |
| Projected cost per line | Only if you build the formulas | Usually built in |
| Two or more people | Risk of versions drifting | One shared budget |
| VAT tracking | Manual, easy to mix up | Recorded per invoice |
| Comparing quotes | Manual mapping | Side by side, allocated to lines |
| On a phone | Awkward | Designed for it, if it works in the browser |
| Documents | Stored separately | Attached to entries |
| Your data | Yours, in a file | Check the app lets you export it all |
Other tools exist too. For an early estimate, Build It has a self build cost calculator for houses and bungalows, powered by its estimating service. There are also project management apps aimed at self builders; look at what each one does for budgeting specifically before you choose.
When a spreadsheet is enough
Stick with a spreadsheet if one person runs the budget, the project is simple, you have one main contractor on a fixed price, and you’re comfortable with formulas. Keep it on one shared copy, back it up, and review it weekly.
Consider moving on if two or more of you need to update it, you’re managing lots of trades and quotes, you’re reclaiming VAT on a lot of invoices, or you find you’ve stopped updating it because it’s become a chore. A budget that isn’t current is worse than none, because it gives false comfort.
On our build
We started Highfields with a spreadsheet and a crude cost per m². Simon kept the spreadsheet; Jo was running the build day to day and couldn’t easily see where we stood from site. Quotes covered different things, and we kept arguing about figures with and without VAT. That is why we built Self Build Budget.
How Self Build Budget helps
Self Build Budget does what a good spreadsheet does, with budget, spent, remaining and projected cost for every line and stage, without the formulas to maintain. Up to five people can share one project, it works in a phone browser with no app to install, AI scanning reads quotes and invoices, and you can export all your data and documents at any time. The free plan gives a ranged estimate; the working budget is on Standard (£12 a month).
Questions people also ask
Is there a free self build budget spreadsheet? Yes. You can download ours, and many self build forums share templates too.
What columns should a self build budget spreadsheet have? Budget, quoted, committed, paid, projected cost and variance per line, plus net, VAT and gross on your payments log.
Can I move from a spreadsheet to an app halfway through? Yes. Set up the stages, enter accepted quotes and payments to date, and carry on. It is usually a few hours’ work.
Excel or Google Sheets? Either works. A shared online sheet avoids version problems between partners, but protect your formula cells.