How much contingency for a £98,980 London warehouse renovation?

M

makeTheCanvas

Property investor
Established
The £98,980 estimate looks workable on paper, but I’m reluctant to choose a contingency before the hidden conditions are better understood. This is a 2,260 sq ft London warehouse, with work planned to the kitchen and bathrooms as well as finishes, service checks and some energy improvements. There is no planned extension.

My concern is that moisture, inaccessible plumbing or remedial structural work could disrupt the sequence and consume the reserve before finish choices matter. Which inspections should come first, and what should contractors state about opening up, making good, material lead times and excluded work? I’d then like to set a contingency against the remaining unknowns rather than apply a percentage blindly.
 
Until the building has been opened up, I’d model 15% contingency and also test whether the project still works at 20%. The key distinction is between a pricing allowance and genuinely unknown work.

Ask each contractor for a written exclusions list, not just inclusions. Specifically pin down making good after electrical and plumbing work, access equipment, waste removal, protection, testing, and who pays if services are found somewhere unexpected.
 
How many bathrooms, and are the kitchen and drainage points staying near their present locations? Moving water and waste across a warehouse floor could change both cost and sequence considerably. I’d also want to know whether the £98,980 includes tax, professional fees and any approvals, or is purely the construction figure.
 
One more question: what are the floor, walls and roof currently doing after heavy rain? A normal visual visit may not explain staining or intermittent damp. Before fixing flooring or improving insulation, investigate moisture paths and agree how the contractor will record conditions found during strip-out.
 
I wouldn’t automatically set aside 20% just because it is London. Contingency should reflect unresolved scope, not postcode. If the electrical installation has been properly inspected, drainage routes traced and moisture investigated, a lower reserve may be defensible. If those items remain assumptions, even 20% can provide false comfort because the base scope itself is incomplete.
 
The phrase “electrical checks” needs expanding before tender. Does the price cover inspection only, identified remedial work, alterations for the kitchen and bathrooms, or replacement of anything unsuitable? Also ask whether opening walls or ceilings, fire-stopping penetrations and subsequent decoration are included. Those interfaces are where separate trade prices often leave gaps.
 
Sequence the investigation before committing to finishes: survey and service tracing, limited opening-up where acceptable, scope revision, then contractor pricing. After that, identify any materials or equipment with long lead times and place decisions against the programme. Ordering early helps only if dimensions and service requirements are settled; otherwise it can lock in the wrong solution.
 
Don’t overlook approval timing. Depending on the existing and intended use, the works and the building arrangements, there may be questions for the relevant London authority, building control, landlord or freeholder. I’d ask the designer or contractor to list every assumed approval, who is responsible for it, and what work cannot start until it is resolved. No point carrying a cost contingency while ignoring programme contingency.
 
I’d turn the £98,980 into three columns: defined work, provisional allowances and exclusions. Then obtain targeted information on the slab and visible structure, electrical condition, plumbing/drainage routes and moisture before comparing tenders. Keep the contingency outside the contractor’s working budget, with changes priced and approved individually. That will tell you far more than asking each bidder for a single reassuring total.
 
You must log in or register to reply here.
Back
Top