For an office fit out project to be viable, most clients are understandably looking for some metric of return on investment. An office fit out is, after all, one of the best ways to invest in your business growth. Where tracking ROI fails, however, is when the project ends up costing much more than had originally been budgeted for.
This scenario happens more often than most people would think, not because of bad luck, but because the original project scope is missing key information. “Hidden” costs are often overlooked, contingency is treated as optional, and if surprises arise on site, there is no budget left to absorb them.
This guide will help to explain where your money is going, allowing you to better attribute every pound spent.
Where Does the Money Actually Go?
Before trying to manage a budget, it makes sense to study the anatomy of it.
Typically, office fit out costs fall into six loose categories, as indicated in the table below.
The percentages in the table are average for a mid-spec CAT B office fit out in the UK. These will shift from project to project due to factors such as overall size, the age and condition of the building, the site location and the proposed material and product specifications.
| Category | % of Budget (approx.) | What’s included | Worth knowing |
|---|---|---|---|
| Construction & structural | 25–35% | Partitions, flooring, ceilings, structural changes | Hard to cut without long-term consequences |
| Loose furniture & bespoke joinery | 20–30% | Desks, tables, seating, storage, pods, booths | Invest in ergonomics; flex on aesthetics |
| Mechanical & electrical | 15–25% | Heating, cooling, fresh air, plumbing, lighting, power, data | Don’t cut here — compliance risk if you do |
| Technology & AV | 10–15% | IT infrastructure, screens, video conferencing, booking systems | Consider lease vs. buy early on |
| Dressing items | 5-10% | Branding, artwork, planting accessories, dressing items | Most flexible line in the budget |
| Professional fees | 5–8% | Architect, PM, specialist consultants | Often underestimated at the outset |
| Contingency | 10–15% | Unforeseen costs | Non-negotiable |
The above figures should be used as a sense check against your ideas and are not a fixed formula. They are very much just a guideline, as each project is different. For example, if you are a multinational business, then you may require a higher AV spend for video meetings. On the other hand, a law firm may need to invest in higher-specification private meeting space.
Contingency and Why 10% Is Often Too Little
Your contingency amount should be considered carefully, as it is often a misunderstood area of office fit out projects.
The most common misappropriation we see with clients is treating contingency as a sign that their project planning has been imprecise. However, the reality is quite the opposite. An appropriately sized contingency allowance is proof that you’re planning with honesty.
For most office fit out projects we recommend setting aside between 10% and 15% of your total budget. If the space you are taking is more complex or situated in an older building, we would recommend the upper limit of 15%.
What is contingency there for?
- Structural issues which are discovered during the strip out phase. This can include asbestos, drainage issues or non-compliant fire-stopping.
- Specification changes – it’s not ideal to change your specifications after starting a project; however, this is exactly what the contingency is for.
- Fluctuation in the lead time or prices of materials. Typically this only applies if there is a long wait between receiving a quote and getting on site.
- Scope creep – new ideas often come to life as projects develop; we most commonly see rises in spending on new technologies and furniture.
- Programme delays which then have a knock-on effect on the contractors’ rates or preliminary costs.
The most common contingency mistake we see is simply setting the amount too low. It’s meant to be a buffer which is there to protect you. If your project then lands under budget, it’s a sign of effective planning, not that you set your contingency too high.
Our final point is to remember that contingency is NOT a substitute for thorough pre-contract surveys. Surveys are about understanding the building and therefore are a vital step in the office fit out process. The better you understand the building before starting work, the less likely you are to need your contingency. The best plan is always to engage with a professional to carry out a building condition survey as early as possible.
Where to Spend vs Where to Save
Not all budget cuts carry the same risk. Some areas of your office fit out project offer genuine flexibility; this allows you to make savings without having a large impact on the completed space. However, it’s important to stress that cutting spending in some areas may cost you more in the long run.
Worth Investing In
Ergonomic Furniture: It’s obvious that employee wellbeing should be at the forefront of office fit out design. Keeping your employees healthy and happy is a great way to ensure long-term performance. It’s been proven many times that poor workstation setups contribute to musculoskeletal problems, which, in turn increase absence rates and lower productivity. Investing in the comfort and usability of good-quality furniture makes a world of difference.
Acoustic Design: Poor acoustics are the bane of many office workers’ lives. It’s one of the top complaints we see when surveying workplaces. It affects concentration, communication and staff wellbeing. The cost of properly specified acoustic partitioning and surface treatments is modest compared to the cultural impact of getting it wrong. Once a fit out is complete, improving poor acoustics can become disruptive and feel like an afterthought.
Mechanical and Electrical Infrastructure: Cost-cutting on M&E will affect day-to-day operations of the office. Undersized or incorrectly specified equipment does not only affect compliance but also creates uncomfortable working conditions and generates expensive remedial work. M&E is one of the most intrusive aspects of an office fit out to rectify once a project is completed.
Technology: Even if you are not installing every piece of kit on day one, it costs very little extra to install cable containment and data conduit during the fit out. Retrofitting it later, once the space is occupied, is disproportionately expensive and disruptive. Think ahead about where you may want screens, video conferencing equipment and collaboration tools, and build that provision into the works now.
Where Savings May Be Appropriate
Decorative Lighting: It’s essential to spend well on functional, comfortable lighting; however, it’s not essential to opt for light fittings that are more eye-catching to look at. Feature pendants and decorative fixtures are impactful, but the focus should be on lighting your space appropriately before aesthetics come into play.
Wall Graphics: If you need to make savings, this is often an easy win. Simply put, they don’t need to be completed during the main fit out programme and can usually be installed later down the line with minimal disruption. Adding or amending high-impact graphics post-completion (once some more capital is free) is always an option.
Low-use Furniture: As important as good-quality ergonomic furniture is, people aren’t utilising every area all day. Focus more spending on the high-usage, high-impact items, and utilise a more cost-effective range in your secondary or tertiary areas that receive lower usage.
Plants and Soft Furnishings: Biophilia is a great way to boost employee morale and well-being and bring a touch of nature into your workspace. However, they can always be added incrementally post-completion. You don’t have to commit to the forest vision from day one.
The Budget Mistakes That Catch Businesses Out
There are mistakes which we see crop up time and time again to do with budget. Most of these issues are entirely avoidable with the correct preparation and forethought:
- Seeking quotes before a full schedule of works is in place. Without a consistent scope, you cannot meaningfully compare quotes from different contractors.
- Leaving VAT, professional fees and furniture out of the headline budget. These are real costs. VAT alone adds 20% to your contractor invoice. Include them from the outset.
- Treating the contractor’s initial quote as the final number. Quotes are based on the information available at the time. Surveys, specification changes and unforeseen site conditions will all influence the final cost.
- Underestimating technology and AV spend. For most businesses this settles at 10–15% of the total fit out cost. In tech-heavy environments it can be considerably higher. This is not a category to leave until the last minute.
- Failing to account for business disruption. Real costs that fall outside the contractor’s scope include temporary relocation, equipment storage, and the time your team spends moving instead of working.
Final Thoughts
Exceeding your budget for an office fit out project is rarely the result of a single cause. Most of the time it’s an accumulation of small oversights.
Businesses that stay within their allocated budget aren’t the ones that spend the least; they are, however, the ones that plan the most. The most successful clients start by asking the most questions early, performing a rigorous professional survey, and treating their budget as a live document throughout the project.
As always, Avent Interiors is here to help – if you’re planning an office fit out and want a clear, honest opinion of what it’s likely to cost, we can assist. If you decide the budget is appropriate for your business, then we offer a full turnkey solution from initial space planning to construction, furniture installation and even office relocation services.
Get in touch today for your free site survey and no-obligation quotation.