A desktop rebuild cost assessment is a professional assessment of the estimated reinstatement cost of your property, produced remotely by a Chartered Surveyor-led team using planning records, mapping data and professional cost analysis instead of a site visit. Choosing the wrong property for this route may produce an estimate that your insurer accepts today but disputes when a claim is made.
That gap between the assessed figure and what actually holds up quietly builds into underinsurance. It rarely shows up until the worst possible moment, when a claim is being assessed and the sum insured falls short. For commercial property owners, brokers and managing agents, knowing when a remote assessment gets you there, and when it doesn’t, is the difference between a formality and real protection.
What Is a Desktop Rebuild Cost Assessment?
A desktop rebuild cost assessment estimates what it would cost to rebuild your property, using existing planning and mapping records rather than a physical inspection, with an RICS Chartered Surveyor producing the final figure.
Desktop assessments draw on gross external area, construction type and building materials to produce the figure, cross-checked against planning and mapping records rather than confirmed on site. In that respect, it is informed professional judgement applied to existing data.
The output format is similar to a full on-site report: a rebuild cost, broken down by element, that may assist in reviewing the buildings sum insured. The difference lies in the inspection scope and the limitations of the method, as the figure is produced without a site inspection. There’s no physical inspection, no walk-through, no chance to see what’s actually behind the façade. The result depends entirely on the accuracy of the information available and the experience of the surveyor interpreting it.
For the right property, this is simply a faster way to reach a reasonable rebuild cost estimate based on the information available, without the fee or lead time of a site visit. The question that actually matters is which properties qualify as right.
What’s the Difference Between a Desktop and On-Site Assessment?
An on-site assessment means a Chartered Surveyor physically inspects the property: measuring, photographing and noting construction quality, condition and any features that affect cost. A site visit catches things no remote process can: non-standard finishes, structural alterations, a hidden plant room, or a mezzanine level that never made it onto the original planning drawings.
The desktop route skips that step entirely. It works from what’s on record, not necessarily what’s actually there today. For anything altered, extended, or built before digital planning records existed, the gap can be large enough to under-value the rebuild cost without anyone noticing until it matters.
Every desktop assessment carries this trade-off, whether you’ve named it or not: faster and cheaper against someone actually seeing the building for themselves. Which side makes sense depends entirely on the property.
When Does a Desktop Assessment Work for Your Property?
Standard properties, ones where the footprint, construction type and materials can be confirmed reliably from existing records, are reasonable candidates. A conventional retail unit, a modern office suite, or a steel-frame warehouse with no unusual additions will typically fit. If the building matches its planning drawings and hasn’t been altered since, the process moves quickly, usually within days rather than weeks.
Smaller structures attached to the main building, a garage, a storage outbuilding, a loading canopy, can usually be factored in from records too, provided they’re clearly documented and don’t introduce construction types the process wasn’t built to handle.
In short, a property that suits a remote assessment has a straightforward and adequately documented construction history, with nothing bespoke or undocumented that requires a site inspection.
When Do You Need a Full On-Site Assessment Instead?
Some properties simply aren’t candidates for this route, whatever the fee difference. Protected Structures (under Irish planning legislation), properties built with unusual or heritage materials, and buildings with complex internal layouts, mezzanines, hidden extensions, or mixed residential and commercial use under one roof, all need a surveyor on site to produce a properly evidenced assessment.
High-value properties carry the same logic. The larger the potential gap between an estimated rebuild cost and the real one, the smaller the acceptable margin for error, and the more a physical inspection earns its cost. If your building has been extended, converted or altered since it was built, and those changes aren’t clearly reflected in current planning records, a site survey is strongly recommended to help ensure the assessment is appropriate.
Why the Data Behind Your Rebuild Cost Assessment Matters
Not every rebuild cost assessment is built on the same foundation. Its accuracy depends entirely on the quality of the information feeding it: accurate mapping, current planning records, and current construction cost information rather than figures from two or three years ago.
Generic online calculators fall short here too. The SCSI’s house rebuilding calculator is built for standard estate-type houses, and the SCSI says it should not be used for one-off homes in the countryside or period properties. A commercial rebuild cost assessment needs a Chartered Surveyor applying professional judgement to the specific building in front of them, rather than a per-square-metre figure pulled from a residential model. Without that judgement on a complex building, the result is an unreliable estimate rather than a professional rebuild cost assessment.
Getting Your Sum Insured Right
Where a buildings sum insured is inadequate, many commercial policies may apply the Average Clause: if the declared figure is found to be below the true rebuild cost at the time of a claim, your insurer can reduce the payout proportionally, even where the rest of the claim is entirely valid. An inaccurate rebuild cost assessment doesn’t cost you a slightly wrong number on a form. It can result in a reduced claim settlement when you need the full amount.
This is why insurance brokers increasingly ask for a professional assessment rather than relying on a client’s own estimate or a figure carried over from a previous policy. A professional assessment helps the property owner manage underinsurance risk and supports the broker placing the cover.
Why Rebuild Costs Are Rising Faster
The SCSI’s Tender Price Index for August 2026 shows commercial construction tender prices rose 3% nationally in the first half of 2026, the largest six-monthly increase in three and a half years and a trebling of the 1% rise in the previous six months. Commercial tender price inflation is now running at 4% year-on-year, and the SCSI names the conflict in the Middle East as one of the key drivers. A rebuild figure set a few years ago can fall behind quickly in a market like this. Read more on how rising inflation threatens your property’s rebuild costs and sum insured
The regional detail makes the case for a proper assessment even sharper. In the first half of 2026, tender prices rose 3.3% in Munster, 3% in Connacht and Ulster, 2.5% in Dublin and 2.3% in the rest of Leinster. A single national average hides which properties are ageing out of their sum insured fastest, and a rough percentage applied to an old rebuild cost figure is not the same as a proper reassessment.
Trevor Kelly has made a version of this point publicly. In comments to The Irish Times, he warned that businesses, not just homeowners, are leaving themselves exposed to significant financial loss by failing to update their cover as rebuild costs move. A faster headline rate only widens any gap that has already built up.
How Often Should You Get a Rebuild Cost Assessment?
A full on-site reinstatement cost assessment every three to five years, with a desktop review in the interim, is the standard most commercial property owners should work to. The mistake isn’t choosing the wrong type of assessment. It’s treating any single one as a figure you never need to revisit.
The interim desktop review doesn’t replace the full assessment. It supports an up-to-date reassessment between full assessments, catching the effect of construction inflation before it turns into a gap between what you’re insured for and what it would actually cost to rebuild.
For an owner managing a single commercial building, that discipline is sensible. For anyone managing a portfolio, it’s close to essential. A remote review can be run across multiple properties far more efficiently than a full site visit to each one, keeping every sum insured broadly current until the next full assessment falls due.
If you’re weighing up whether your property qualifies for the desktop route or needs a surveyor on site, please get in touch and we can advise which route is appropriate. Send us the basics of the building and we will advise.