Independent help in construction
For private clients I help with estimates, on-site visits, representation during construction and written technical opinions. For companies I control data and costs with ZERLOS — the system I develop.
Certified construction specialist Jānis Zvaigzne, construction practice certificate No. 4-06636 — View in the Latvian Construction Information System register, sphere “Building works management and construction supervision” (Ēku būvdarbu vadīšana un būvuzraudzība)
- years of experience in construction
- 0+
- completed projects
- 0+
- independent perspective
- 0%
For Individuals
An independent eye on your build
Why this offer exists
Working with construction clients for years, I keep seeing the same picture – confusion about the process, the costs and how the work is progressing. The result: stress over unexpected extra costs and a result that doesn't match what was expected.
That's why I help you find the “hidden rocks” that are already undermining your build and would harm both the house and you for years to come.
Your view VS reality
- In a listing or render you see a finished house — not what's under the finish or whether the structure was calculated correctly
- The estimate looks complete, but often has vaguely described or missing line items
- Every “one more improvement” during design quietly raises the total — often by thousands of euros
- The builder says everything is on track — without an independent specialist's eye, you can't check it
The first step is simple
Submit your estimateSend me your construction estimate or project. You'll get my initial assessment – which problem areas and “hidden rocks” are already visible in it.
Then you decide: you can order a detailed, paid assessment to take to your designer or builder with confidence.
I offer several ways I can help you!
Estimate / project execution review
from €50
- Cost logic and quantities
- Hidden line items
- Cost check against current market prices
- Material compliance against the project
- Project quality assessment
- Construction progress review against the approved estimate
reply within 24h · PDF/Excel
Request thisOn-site visit
from €150
- Visual check of construction, building-services and finishing quality
- Comparison of the builder's completed work and payments against what's actually built
- Comparison of installed materials against what was specified and estimated
- An independent report file with attached photos and comments
- If needed, technical equipment can be used for measurements (thermal camera, wood moisture, etc.)
- Additional advice for improving project quality
up to 2h
Request thisClient representation during construction
Depends on the project
- Evaluating subcontractor offers
- Recommending and sourcing trustworthy contractors
- Checking build quality in real time
- Providing recommendations to improve project quality
- Keeping the construction schedule under control
- Professionally resolving any conflict situations that arise
throughout the entire build
Request this
Technical opinions
from €200
a written technical opinion based on a visual review and documents
On an existing building or on works already done — with measurements where they are needed. You can show the opinion to the builder, the seller, the building manager or your neighbours.
Where the question needs a designer's assessment, I bring in a designer in that field.
Request an opinionWhen it helps
- Ventilation and air quality
- Moisture and mould
- Insulation and thermal bridges
- Roof and facade
- Visible structural defects
- Quality of works against the design and contract
- Hidden works
- A dispute with the builder or seller
Each opinion is prepared and signed by Jānis Zvaigzne — certified construction specialist, construction practice certificate No. 4-06636 — View in the Latvian Construction Information System register, sphere “Building works management and construction supervision”.
It is not a construction expert examination (būvekspertīze) and not a technical survey report under LBN 405-21.
SIA JZ Advisory is not registered for VAT. The final price depends on the property's location and the complexity of the work.
Estimate audit examples
PROGRESS BY WORK TYPE
- Structural works100%done
- Roof99%done
- Windows, doors, gates92%⚠ in May
- Floors79%⚠ in May
- Utilities (MEP)50%partial
- Preparation works75%partial
- Interior finishing26%⚠ in May
- Facade7.5%⚠ in May
- Landscaping0%not started
⚠ = declared as "completed in May 2026" — requires on-site verification
Progress by work type SUMMARY BY SECTION
Section Estimate Market price Overpayment % Preparation works € 9,240 € 6,460 € 2,780 30% Structural works⚠ labor rate €25/h € 61,912 € 49,981 € 11,931 19% Roofing⚠ quantities adjusted per design € 53,765 € 40,339 € 13,426 25% Windows, doors, gates⚠ PVC instead of ALU, 83.7 m² € 70,099 € 63,443 € 6,656 9% Floor structures € 34,561 € 29,283 € 5,278 15% Interior finishing works € 76,236 € 63,839 € 12,397 16% Facade⚠ €25/h · ⚠ quantities · ⚠ timber facade missing from estimate € 49,659 € 41,374 € 8,284 17% Utilities (MEP) € 70,254 € 59,850 € 10,404 15% Landscaping € 36,502 € 39,530 -€ 3,028 -8% TOTAL ESTIMATE (EXCL. VAT) € 462,229 € 394,099 € 68,130 15% Total overpayment = ESTIMATE TOTAL − MARKET TOTAL (positive = client overpays)
Summary by section ESTIMATE AUDIT — OVERPAYMENT VS. MARKET PRICES 2025–2026
Total overpayment: 68 130 € or 14.7% above market
- >25%
- 10–25%
- ≤10%
- cheaper in estimate
- Preparation+2 780 €
- Structural works+11 931 €
- Roof+13 426 €
- Windows/doors✓+6 656 €
- Floors+5 278 €
- Interior works+12 397 €
- Facade⚠+8 284 €
- Utilities+10 404 €
- Landscaping−3 028 €
⚠ Additional costs (not included in estimate)
Timber facade 201.7 m² (AS-1.1 + AS-2.1): +14 399 €
Solar panels 10 kW (in estimate, not completed): +8 850 €
REMAINING WORKS
REMAINING (EXCL. VAT)
170 453 €
market prices 2025–2026
REMAINING (INCL. 21% VAT)
206 248 €
to be paid to finish the house
WHOLE HOUSE AT MARKET PRICES (INCL. VAT)
483 215 €
vs estimate: 559 297 € — saves 76 082 €
Overpayment vs. market prices
Examples of project mistakes
Roof covering — recommendation to switch to PVC membrane 
Parapet thermal insulation was not designed in 
Incorrectly designed ventilated façade
Choose from the offers above and submit your request!
For companies
Data and cost control inside your company
I join your team as an external cost controller and work inside your ZERLOS, so management sees every project's profit or loss while the work is still running, not after handover. I set the system up for your company, so you do not have to run yet another system yourselves.
What is included
ZERLOS set-up for your company
Company costs, hourly rate, projects and estimates.
Data control
Hours, expenses, invoices and stock are entered correctly, completely and attached to the right estimate.
Cost control
Estimate vs actual on every project, and early warnings while there is still time to act.
A regular report to management
With concrete recommendations.
Training for your staff
For working with ZERLOS, and support when questions come up.
Working format
Hybrid / remote
Who it is for
Construction companies and subcontractors that want cost control without hiring a full-time controller.
Fee
The fee is agreed individually with each company and already includes the ZERLOS subscription.
Request a call
Tell me about your company and your projects — I will get in touch to discuss your situation and agree on the scope of work.
What ZERLOS looks like — see the modules
ZERLOS system
ZERLOS — a construction management system for companies, developed by SIA JZ Advisory. Explore it module by module.
Loading the ZERLOS module walkthrough…
Visit zerlos.eu to see the system in detail and book a demo
About me
More than 10 years in construction — from the job site to production management.
Jānis Zvaigzne
Certificate
Certified construction specialist Jānis Zvaigzne, construction practice certificate No. 4-06636 — View in the Latvian Construction Information System register, sphere “Building works management and construction supervision” (Ēku būvdarbu vadīšana un būvuzraudzība)
Let me introduce myself:
I've been working in construction for over ten years now — from a job site in Latvia, to managing Europe's largest construction project in Sweden, to running a modern, efficient production facility today. This path has let me see the process the way few people ever do — from the inside.
I like putting things in order — whether that's construction technology, people's work, or the data behind it. And it's exactly this experience that made me realize: many people and companies are missing someone they can trust, someone standing on their side — not on the side of the contractor or the seller.
That's why I'm here.
Experience
2014 – 2018 · 4 years
Construction worker, then Site manager's assistant
2018 – 2024 · 6 years
Site manager
6 years of experience across various projects in Riga – timber-frame, reinforced-concrete, and block houses, as well as a range of high-end building restorations.
2024 – 2025
Site manager/Planner in Sweden
Greensteel Boden, Europe's largest project, and Volvo's NOVO electric battery plant, Gothenburg
January 2025 – July 2026 · 1 year 7 months
Production manager
timber-frame modular homes – around 25 completed projects
Education
- Riga Construction College – Construction Technician (Level 3 qualification)
- Riga Construction College – Building Site Manager (Level 4 qualification)
- Riga Construction College – Building Information Modeling (BIM) Coordinator (Level 4 qualification)
Skills
- Construction software development
- Estimating and cost control
- AutoCAD
- Revit
- BIM software
- Solibri
- DraftSight
- Latvian / English / Russian
Software I work with
- Excel
- Revit
- Solibri
- AutoCAD
- BimVision
Excel
Revit
Solibri
AutoCAD
BimVisionGet in touch
Contact details
Company details
SIA «JZ Advisory»
Registration number: 40203760797
Registered address: Cēsu novads, Drabešu pagasts, Amata, "Jaunjūgas 1" - 1, LV-4101
Construction specialist
Certified construction specialist Jānis Zvaigzne, construction practice certificate No. 4-06636 — View in the Latvian Construction Information System register, sphere “Building works management and construction supervision” (Ēku būvdarbu vadīšana un būvuzraudzība)