Product
Overview
The commercial operating system for construction. Capture a commercial event once, every downstream workflow stays connected.
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Estimate & tender
Tendering
Documents & comms
DocumentsCorrespondence
Contract models
Fixed, cost plus & open book
Claim a fixed sum, reimburse at actual cost, or bill fully open book. ClaimStack handles each, the right way.
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Solutions
Overview
Built for every side of the contract. One commercial record the whole project team can trust, head contract to supplier.
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For subcontractors
Free to collaborate
Invited to a project? Submit claims and variations in a format that holds up, free forever.
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Resources
Overview
Practical guides on claims, variations and contracts, plus how ClaimStack connects, who's behind it, and how we keep your commercial data safe.
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See it on your project
A 30-minute walkthrough on your numbers, where the margin usually leaks.
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Pricing
Product/Contract models

Priced any way. Claimed the right way.

Fixed lump sum, cost plus and open book, all on one connected record. Set how a contract is delivered and ClaimStack drives the claim the right way, with variations, retention and assessment consistent across every model.

One system, whichever way the contract is priced.

Most systems do one contract type well and push the rest into spreadsheets. ClaimStack supports fixed lump sum and cost plus natively, billed open book, so the model is a setting on the contract, not a workaround beside it.

01 · Fixed lump sum

Claim the agreed sum, to completion.

Claim against the agreed contract sum and your cost breakdown, line by line. Variations adjust the sum through the register, and every claim is assessed against the live contract position, cent-perfect from claimed to certified.

Progress claim 07 · Fixed lump sum
Main works · Building A
Cent-perfect
ItemContractTo dateThis claimPreliminaries$320,000$280,000$40,000Structure$1,150,000$1,050,000$150,000Facade$480,000$210,000$90,000Total$1,950,000$1,540,000$280,000
This claim$280,000
Less retention (5%)-$14,000
Due this claim$266,000
02 · Cost plus

Reimburse actual cost, plus your margin.

ClaimStack aggregates the actual cost as it lands, labour from timesheets, receipts and subcontractor costs grouped by budget category, then adds your margin and monthly management fee, with retention. The monthly claim packages itself from the costs already captured, so there is no side ledger to rebuild.

Cost-plus claim · June
Main works · open book
Cost + margin + fee
LabourFrom timesheets$84,200
MaterialsFrom receipts$46,750
SubcontractorsBy budget category$120,000
Cost this month$250,950
Builder margin (12%)+$30,114
Management fee (monthly)+$8,500
This claim$289,564
03 · Open book

Every cost, in full view.

Cost-plus claims are billed open book. Each one carries a supporting pack that shows the principal every actual cost and its backing document, receipts and invoices included, so the reimbursement is transparent and defensible, with nothing gated.

Supporting documents · open book
Every cost, with its backing
Nothing gated
Timber supplyINV-4471$18,240✓ Attached
Crane hireINV-2210$9,600✓ Attached
Site labourTimesheet wk23$12,480✓ Attached
ConcreteREC-8890$6,300✓ Attached
4 documents attached$46,620
The same discipline

Consistent across every model.

Whether the contract is a fixed sum or reimbursed at cost, the commercial controls stay the same, so nothing is run a different way on a different job.

VariationsCaptured against the clause that gives rise to them and assessed line by line, whichever model the contract runs on.
RetentionHeld to your rules, with caps and the option to retain on margin and fee, applied the same way on lump sum and cost plus.
Assessment & SoPAEvery claim assessed and scheduled cent-perfect, compliant with Security of Payments, with the full audit trail behind it.
Fixed
or reimbursable
Open
book by default
1
Connected record
0
Double entry
Price it any way.
Claim it the right way.