The Extension Plan - costs, timeline, forecast

This complete breakdown of extension costs, timeline and forecasting will help you plan your project the right way

It includes real figures and dates from our 40 week, two-storey extension completed in 2021 in the Midlands for under £100k. You can use it to consider every aspect of the build, from foundations to ridge tiles, in terms of costs and timings. We've plotted when the major costs go out and where likely breaks in the works will occur. You should feel much more confident about what's involved with this plan in hand.

What you get

An Excel file featuring the following:

• Sheet 1: Week by week breakdown of costs and activity (with running total)

• Sheet 2: Breakdown of cost by % showing where the money went

• Sheet 3: Cost vs time shows at a glance at which stages the money went out slowest/fastest

• Sheet 4: Forecast, giving a rough breakdown by area with a column for your own figures, and the difference between that and what you've borrowed

What did we have done?

Our extension was 4m x 8m approx. It opened the back wall of the kitchen into a new dining/living area with downstairs WC and cloakroom. We blocked the old door into the kitchen from the living room and added internal double doors instead. We added underfloor heating (3 loops), a new 40kW boiler, tiled throughout downstairs. Insulation between the floors, complete plumbing and electric fittings. The new room upstairs has an en-suite and the old box room was extended out to become the longest room in the house now, with plenty of room for the children to grow into. We re-fitted the old bathroom to bring it up to spec also. Finally we added a patio with 3 crates of flagstones required as it went around the house and up the garden path.

We did what we could to help - loaded skips, painted and sanded, kept things moving over the weekend for the team, through lockdown, homeschooling and a bout of COVID for one of us. But there's only so much you can do while still working and not getting in the way. The team had to take breaks in the winter for the blockwork but in general we were their priority and they did right by us the whole way through, pushing us through to the end of the 40 weeks with great attention to detail.

Full photo log and write-up is available on the blog.

*Gumroad is still charging in USD for the moment, so a US sales tax is added, but they handle all the payment side and are very quick and easy to use.

Following your purchase, I'll send the invite link to the file for you to copy and download.