In the world of construction, precision is key – especially when it comes to quoting and estimating costs. Yet, there’s one area where even the most experienced builders in the South West are still getting caught out: PC (Provisional Cost) sums. If you’re a builder working in Cornwall, Devon, Somerset or Gloucestershire, this article is for you.

Provisional Cost sums can quietly undermine your profit margin, create client confusion and open the door to disputes. In this blog, we’ll explore how PC sums work, why they’re so commonly misused and how builders are losing thousands because of them. More importantly, we’ll explain how accurate construction estimating, material takeoffs and localised estimating services can prevent these losses.

1. What Are PC Sums and Why Do They Exist?

PC sums are allowances included in a quote or tender for items that haven’t been specified at the time of estimating. They usually apply to:

• Kitchen fittings
• Sanitary ware
• Tiles and flooring
• Appliances

For example, you might allow a PC sum of £3,000 for a bathroom suite in a project where the client hasn’t yet made a final selection. This placeholder is intended to be adjusted later once the actual products are chosen.

But here’s the problem: PC sums rarely reflect real-world prices.

2. The Problem with PC Sums in the South West

Builders across the South West (especially in places like rural Devon and Cornwall) face unique challenges:

• Longer lead times and delivery costs inflate product pricing.
• Client preferences often shift toward higher-end finishes.
• Changing specs post-contract cause rework, disputes and margin loss.

A PC sum of £1,500 for a kitchen sink and tap might make a quote look competitive, but if the client selects fittings worth £4,000, guess who absorbs the extra cost?

“PC sums are a ticking time bomb in small-scale construction projects,” says Mark, a builder from North Devon. “We lost over £7,000 last year just from clients choosing higher-spec items than we allowed for.”

 

3. How PC Sums Affect Builders’ Bottom Lines

a) Unplanned Variations

Every time a PC sum is exceeded, it results in a variation and variations take time to manage, price and justify. Often, they’re not charged correctly.

b) Client Disputes

Clients may misunderstand PC sums as fixed prices, leading to disappointment and tension when the final bill arrives.

c) Damaged Reputation

Even if you’re right, clients can perceive it as “hidden costs”, affecting future referrals.

d) Reduced Profit

Underquoted PC sums mean you’re starting the job with a financial hole to climb out of.

4. The Role of Accurate Estimating in Avoiding PC Sum Pitfalls

This is where a professional construction estimator or building estimator can make a world of difference. Instead of relying on vague allowances, accurate estimating services  (like those offered by TruTrade) ensure your pricing reflects actual material and labour costs.

Our team uses leading construction estimating software and up-to-date local pricing data to:

• Provide real-world allowances
• Include full material takeoffs
• Offer alternative pricing options for different client budgets (dependent on spec and how much detail you give us)

With tools like our estimating service, builders across the South West are cutting out guesswork and protecting their margins.

5. Real Case: A Kitchen in Cornwall That Cost £4,500 More Than Quoted

A builder in Truro allowed a PC sum of £6,000 for kitchen units, sink, appliances, and worktops. The client chose a bespoke oak kitchen from a regional supplier, totaling £10,500.

The builder hadn’t clearly communicated the PC sum concept, and the client refused to cover the difference. It led to a months-long dispute and a dent in the builder’s reputation.

By using a building estimating service with itemised allowances based on local supplier quotes, and clear client communication, this could have been avoided.

 

6. Better Alternatives to PC Sums

a) Detailed Material Specifications

With a complete material take off, you can give fixed prices upfront – even for unfinished designs.

b) Tiered Pricing Options

Offer good/better/best costed options to help clients make choices early in the process.

 

7. How TruTrade Helps South West Builders Replace Guesswork with Certainty

At TruTrade, we specialise in building estimates tailored to the needs of South West builders. From Penzance to Gloucester, our estimators provide:

• Line-by-line cost breakdowns
• Regional pricing accuracy
• No ‘PC sums’
• A quote tailored to you and your job so no details are missed out and you can confidently present this to the client

Using our construction estimating service means:

• No more profit-eroding PC sum errors
• Better transparency with your clients
• Improved win rate on competitive quotes

 

8. Tips for Communicating PC Sums to Clients

• Always explain what a PC sum covers and what it doesn’t.
• Document all assumptions (e.g., supplier, brand, style).
• Offer upgrades as line-item options.
• Use visual comparisons to help clients understand cost differences.

Better communication prevents disputes and positions you as a professional.

 

9. Local Pricing = Smarter Quotes

Many South West builders still rely on national averages or out-of-date material costs. But regional variation is real:

• Tiles in Bath can cost 15–20% more than in Plymouth
• Cornwall delivery surcharges can add £300+
• Local merchant prices can fluctuate weekly

Our building estimating service uses local databases to create smarter, more accurate quotes and get a more accurate figure for materials that are area-specific 

 

10. Final Thoughts: Don’t Let PC Sums Undercut Your Success

PC sums are meant to help, not hinder. But without care, they can chip away at your profits, client relationships and reputation. The good news? With the right tools and processes, you can eliminate the guesswork.

At TruTrade, we combine expert construction estimators, detailed building cost estimates, and South West-specific data to create estimates that work in the real world – not just on paper.

 

Need support creating accurate estimates without risky PC sums? Try our estimate online platform or speak to one of our friendly estimators today.