How Zest Digital Built a Growth Engine That Delivers a 4,715% Return On Advertising Spend (ROAS) for Dove Steel Doors

Zest Digital creates a growth engine for Dove Steel Doors that delivers a 4,715% return on advertising spend (ROAS).


As a long-term client, Dove Steel Doors was already seeing consistently strong performance on paid channels, characterised by a 728% year-on-year increase in conversions, and a 68% reduction in cost per acquisition (CPA). But this was no time to put their feet up and relax. Zest Digital set their sights on cutting CPA even further, with the aim of launching overall return on ad spend (ROAS) into the stratosphere.


An ambitious objective demanded a bold strategy shift. Zest Digital had already increased the ROAS from 674% to 2,116% over the course of a year, through a combination of reducing CPA and increasing ad spend. Put simply, this meant Dove Steel Doors were enjoying £21.16 for every £1 they invested in paid advertising. Not bad.

So, their strategy was already driving results, but Zest Digital started to look for new ways to break through this ceiling and increase ROAS further. Zest Digital tried all the tricks in the book: negative keywords; weighting budgets based on trends; split-testing new ad copy, and more. But Zest Digital couldn’t move the needle beyond ~2,000% ROAS.


When it comes to scaling growth, it’s natural to want to spend more and do more. Zest Digital could have increased the volume of incoming leads by lumping more budget into various campaigns, but this wouldn’t have helped the client’s CPA or ROAS.

In fact, their test meant doing the opposite. Zest Digital asked Dove Steel Doors to spend less, with the plan to scale back up over time once they had achieved a low CPA.

Sometimes, to build beautiful architecture, you need to tear down an existing building. And this is exactly what Zest Digital did with Dove’s account – stripping it right back to its foundations, uncovering the winning keywords, optimising obsessively, and iteratively rebuilding from the bottom up.

This meant that Zest Digital could reduce the CPA to its lowest possible level, and keep it there while they raised budgets and tested new campaign strategies. This ended up being far more effective than chipping away at a heavier, more bloated, account.


Zest Digital did the complete campaign strip-back in the first quarter of the year, reducing spend by 54% overnight. Between Q1 and Q2, ROAS jumped by 30%. Over the next 3 months, they nudged spend up, seeing only minor growth in the returns.

Q4 was when things got really interesting. Zest Digital reduced spend again by 24% and boosted ROAS by 28%. And over the first two quarters of the following year, they continued testing while scaling up the ad spend, and added another 43% ROAS.

By the end of this campaign rebuild, the team had increased ROAS from an initial 2,116% to 4,716%. And when you compare the first two quarters year-on-year, Zest Digital reduced CPA by 54% and overall spend by 29%. Conversions jumped by over 55%.

Adam Marston, General Manager, Dove Steel Doors said:

We’ve worked with Zest since 2014, and they still continue to grow our revenue and profits. It’s not common for an agency to ask us to reduce what we spend, but Zest’s test-based approach filled us with confidence and we were happy to trust it. Over a short period, we’ve doubled our margins and our return on what we spend on advertising increased to almost 4,500%. This is quite simply, outstanding value.

About Zest Digital

Zest Digital is an award-winning digital agency, focused on driving revenue growth for its ambitious clients.

Zest specialises in positively influencing the two most important metrics that challenge businesses marketing online today; increasing the volume and quality of traffic and conversions from digital channels.