Hasteron

You're in a very similar position to where I was a couple of years ago — plot already owned, initial design by a relative, and planning advice with a long list of surveys. It does feel like a leap of faith when you’re committing real money before having a firm grasp on build costs. That said, your budget of £300k for 100 m² sounds achievable, especially if you’re flexible on finishes and open to moving in before it’s 100% done. The living roof and floor-to-ceiling glazing could eat a chunk of the budget though, depending on spec. I found it totally possible to get an architect just for technical drawings, but some were pickier than others — it helped to ask smaller, local firms. Also, having a main contractor manage things was a life-saver for me since I didn’t want to be hands-on. Good luck — sounds like a lovely project!

I know this post a bit old but we did something similar on a rural renovation project — open book with a % fee (ours was 14%) and a shared savings model. Honestly, it worked pretty well, but only because we had good visibility and stayed closely involved. The big upside was flexibility and transparency (helped us avoid feeling ripped off), but yes, it requires trust and time to manage. We also capped the total cost to avoid things spiraling. Your idea of sharing savings with the builder sounds fair and could help align incentives. Just make sure you define the terms clearly upfront.

We had a similar situation with a local builder for a rear extension last year, and I remember how stressful it was trying to balance protecting ourselves without upsetting the guy doing the actual work. What helped us was tying each payment to visible progress, like payment after groundwork, after the shell was up, etc. even if we didn’t have an exact breakdown. It gave us some reassurance without making it feel like we didn’t trust him. We also asked for a simple schedule in writing, just bullet points, to keep everyone on the same page. Hopefully this helps a bit 🙂

Not an expert either, but I actually tackled something pretty similar for a retaining wall along my sloped garden path. Your idea sounds totally reasonable. I did almost the same thing with stepped footings to keep the block height level across a slope. In my case, I poured the footing in sections using formwork that followed the slope, but made sure the top edge of the blocks stayed level. It took a bit more time to measure and plan, but it made everything look so much cleaner in the end. One thing I learned the hard way: make absolutely sure your footing is solid and wide enough, especially toward the downhill side. Mine started to shift ever so slightly after heavy rain because I underestimated drainage. Also, if you're doing the pour in sections, make sure to key the footing joins together somehow so you don’t get cracks later. I’d also recommend checking the slope with a string line or laser level before you start pouring — saves a lot of second guessing once you start laying blocks.

Hey Harman, interesting topic. I actually went back and forth on this during our last renovation. We didnt hire a full-service interior designer, mostly because of budget, but we did feel the need for some guidance. I think a lot of people in the selfbuild space are somewhere in the middle, they want their space to look thoughtful and cohesive but either can’t afford a designer or don’t know how to justify the cost. Personally, I would’ve been more likely to hire someone if they offered flexible, modular help, like just layout planning or finish selections.