How to estimate a house in Québec: the steps from bid documents to final estimate

A house estimate isn't one calculation. It's a series of steps, always in the same order, each building on the one before. Skipping a step is the surest way to forget an item or count it twice. Here's the whole process, from the drawings you receive to the price you send, with a checklist at the end.

1. Read the documents before measuring anything

Before the first takeoff line, read the whole package.

• The sheet list. Check that you have every sheet listed on the title page (architectural, structural, mechanical, electrical) and its revision date.
• The specifications and general notes. A note like "moisture-resistant drywall in bathrooms" or "R-24 insulation in basement walls" changes your quantities by type.
• The scales. Each sheet can have its own, sometimes several. One misread scale throws off every measurement on that sheet.
• What isn't drawn. Excluded work, owner-supplied work, allowances (cabinets, light fixtures, flooring chosen by the client).
• Addenda. Note which ones you received. Your price is for those documents, not later ones.

Build your list of questions for the architect or client at the same time. Better to ask now than to find the gap on site.

2. Do the takeoff by trade

Measure in construction order: demolition if any, foundations, framing, roofing, doors and windows, exterior cladding, insulation, drywall, interior finishing. That order helps you not miss anything, and it already gives your estimate its structure.

A few rules that prevent most mistakes:

• Split by section (basement, main floor, upper floor, roof, exterior). A mistake is easier to find in one section than in a whole-house total.
• Measure once, reuse. The walls you measure for framing also drive drywall, insulation and paint. Measuring them three times means risking three different lengths for the same wall.
• Keep measured quantity separate from ordered quantity. 136 lin. ft of wall isn't a stud count: you need a rule (spacing, waste, rounding). Write the rule next to the result so it can be checked.
• Add up before rounding. Rounding piece by piece, then again at the total, inflates quantities.

3. Price it: materials, labour, subcontractors

Every line gets its price, with materials and labour kept separate. That lets you check each column and answer "how much labour is in this price?" later.

• Materials: your suppliers' prices for this project, or your latest known prices, to confirm if the market is moving.
• Your own crews' labour: per unit (per lin. ft, per sq. ft) or per hour, depending on how you work. Use the same method from job to job so you can compare.
• Subcontractors: for plumbing, electrical, ventilation, often excavation and cabinets, get quotes. Compare them on the same scope: a quote that excludes the dumpster or commissioning isn't "cheaper", it's incomplete. Add a price for the exclusions before comparing.
• Allowances: if the client chooses later, carry a clear amount, named as an allowance.

One rule everywhere: each cost is counted in one place only. If a quote includes labour and materials, don't add the materials again elsewhere.

4. Add general conditions

General conditions are the job costs no takeoff produces: site staff (in hours), toilet, fencing, temporary power and heat, dumpsters, permits, insurance. They depend mostly on duration, so you need a rough schedule before pricing them. We have a full guide on general conditions with a worked example.

5. Overhead, profit, contingency

The total of the work plus general conditions is the subtotal: the cost of the project. Then you add:

• Overhead: office costs (rent, accounting, estimating, software), spread over projects as a percentage.
• Profit: what the company actually earns.
• Contingency: a reserve for what the documents don't show yet.

Each is calculated as a percentage of the subtotal. How to work out your overhead percentage is covered in a separate article.

6. Taxes

In Québec, GST (5%) and QST (9.975%) each apply to the amount before taxes. QST isn't calculated on top of GST. Taxes go at the bottom of the estimate, after all adjustments.

Example: a house estimate summary

The summary reads top to bottom, and every line can be checked with a calculator. That's exactly what you want for the next step.

7. Review before sending

Take an hour, ideally the next day, to reread it with fresh eyes.

• Compare to the cost per square foot of similar projects. A big gap isn't necessarily a mistake, but it should be explainable.
• Look for unpriced lines and zero quantities.
• Reread subcontractor exclusions and check that each one is covered elsewhere or excluded from your price.
• Check the largest line in each trade: a scale or unit mistake shows up there right away.
• Reread the list of documents your price is based on: sheets, revisions, addenda.

8. Prepare the client version

The internal estimate isn't what the client receives. The client version usually shows one amount per trade or per section, with taxes at the bottom, without your overhead and profit rates. A common approach: spread the adjustments over each item in proportion to its amount, so the items add up exactly to the amount before taxes.

Add what protects both sides: the documents the price is based on, inclusions and exclusions, allowances, how long the price is valid.

When the drawings change

An addendum arrives after your first price. Don't start over: keep the first version, copy it, fix the affected measurements, then compare the two versions trade by trade. The difference is then explained line by line, and you can justify it to the client.

In KOR

KOR follows these steps in one tool. You open the drawing PDF: sheet names and written scales are read and suggested, for you to confirm. You measure lengths, areas and counts with templates that calculate materials (studs, plates, sheathing, drywall…); drywall, insulation or paint items can reuse the walls measured for framing. The estimate picks up the quantities with separate material and labour prices, general conditions at the top, overhead, profit and contingency as a percentage of the subtotal, then GST and QST. Excel and PDF exports include a client version with one amount per trade or per section. Each addendum can have its own version (V1, V2…) and two versions can be compared. KOR also has two more modules in preparation: bid management and project management.

Checklist

1. All sheets, their revisions and addenda are noted.
2. Specs and general notes are read; questions are sent.
3. Scales are confirmed on every sheet.
4. Takeoff is done by section and in construction order, with the calculation rule for each quantity.
5. Materials and labour are separate; subcontractor quotes are compared on the same scope.
6. Each cost is counted in one place only.
7. General conditions follow the planned job duration.
8. Overhead, profit and contingency are calculated on the subtotal.
9. GST and QST are each calculated on the amount before taxes.
10. The review is done with fresh eyes; the client version names the documents, inclusions, exclusions and price validity.