---
title: "Design-build or architect plus contractor in Ontario?"
url: "https://www.jarviscontracting.ca/guides/design-build-vs-general-contractor"
description: "Design-build or an architect plus a general contractor for an Ontario addition: who carries the risk, who files the permit, and why the 10% holdback applies."
publisher: "Jarvis Contracting"
dateModified: "2026-10-13"
---
# Design-build or architect plus contractor in Ontario?

By Jarvis Contracting. Published 2026-10-05, updated 2026-10-13.

Design-build puts the design and the construction of your addition under one contract with one firm. The architect-plus-general-contractor route splits them into two contracts, and a builder prices the drawings once they're done. Neither model has a credible published saving. As of October 2026 both run under the same Ontario rules. A renovation contract over $50 must be in writing. The final price can't run more than 10% over the estimate unless you agree to new work or a new price ([Ontario, your rights when starting home renovations](https://www.ontario.ca/page/your-rights-when-starting-home-renovations-or-repairs)).

## Key takeaways

- Ontario requires any home renovation contract worth more than $50 to be in writing as of October 2026, so both models end in a signed document that spells out the work and the price ([Ontario.ca](https://www.ontario.ca/page/your-rights-when-starting-home-renovations-or-repairs)).
- Ontario recommends at least 3 written estimates, which is easier when every builder prices the same drawings, a real point for the architect-plus-contractor route ([Ontario's renovation rights page](https://www.ontario.ca/page/your-rights-when-starting-home-renovations-or-repairs)).
- Our permit drawings for an addition are $6,000 to $12,000 before HST, a cost you pay in either model, separately or inside one contract. That's drawings only: permit fees, HVAC engineering, truss design, committee of adjustment applications and anything unforeseen are extra.
- In Whitby, starting work before a permit application costs the greater of $100 or 25% of the application fee, so settle who files before anything comes down ([Town of Whitby, Schedule N, 2026](https://media-003-ca.cdn.govstack.com/whitby-ca/media/5aqjt5ww/2026-building-permit-fees-schedule-n.pdf)).
- You must hold back 10% of the value of work supplied until liens expire, and that applies to design-build and two-contract jobs alike ([Construction Act s. 22(1)](https://www.ontario.ca/laws/statute/90c30)).

## What's the difference between design-build and an architect plus a general contractor?

The difference is how many contracts you sign and when the price gets fixed. With design-build, one firm designs, prices and builds. The people drawing the plans talk to the people who'll frame the walls while the design is still moving, so the budget gets checked as you go.

With the two-contract route, you hire an architect or designer first. They take you from sketches to permit drawings, and often to a full set of tender documents. You then send those drawings to several general contractors, compare bids and sign a construction contract with one of them. If you pay for it, the architect can stay on through construction to review the work.

Ontario tells you to "Always get at least 3 written estimates" ([Ontario.ca](https://www.ontario.ca/page/your-rights-when-starting-home-renovations-or-repairs)). That's easier when every builder is pricing the same drawings, which is a real point in favour of the two-contract route. With design-build you compare firms earlier, on their process, their past work and a budget range, before the drawings exist.

## Who carries which risk in each model?

Risk follows responsibility, and the two models split responsibility differently. Here's how the main risks usually fall on an addition or renovation:

| Risk | Design-build | Architect plus general contractor |
|---|---|---|
| Contracts you sign | One, covering design and construction | Two: one with the designer, one with the builder |
| A gap or error in the drawings | The firm that drew it builds it, so it can't blame the drawings | Designer and builder can each point at the other, and you sit between them |
| Bids come in over budget | Cost is checked while the design develops | Bids arrive after drawings are finished; redesign costs you more fees and time |
| Independent check on the builder | None unless you hire one | The architect can review work and invoices if that's in their contract |
| Competitive pricing | You compare firms early, on a budget range | Several bids on identical drawings |
| Building permit application | Usually filed by the firm as your agent | Usually filed by the designer or builder as your agent, or by you |

Note: This table shows how the models usually divide responsibility; your contracts set the actual split, so read them line by line.

The forum evidence lines up with that table. A lot buyer weighing a design-build firm against a separate architect on Houzz said the appeal was a builder who "will be committed to our budget from the start" ([Houzz discussion](https://www.houzz.com/discussions/5799944/new-construction-architect-vs-design-build-firm)). On RedFlagDeals, homeowners comparing the two routes worry about the opposite risk: one firm marking its own homework, with nobody independent watching ([RedFlagDeals thread, 2015](https://forums.redflagdeals.com/architect-vs-design-build-contractor-1663695/)). Both worries are fair.

## Does design-build cost less than an architect and a general contractor?

There's no credible answer in percentage terms. We couldn't find a published Ontario study comparing the two models on real jobs, and architect fee percentages online come from forum replies and a price-guide snippet we couldn't open. We won't print them as fact.

The same things drive cost in both models. Size and structure come first: a steel beam, underpinning, a new top storey on old walls. Then the finishes, what you find when the walls open, and how many changes you make after the price is set. Our own 2026 range for additions is $350 to $600 per sq ft, and $180,000 to $450,000 for a single-storey rear addition of 300 to 700 sq ft, before HST. That's a range, not a quote: your price comes after James sees the house, and the first estimate is free. Our [home addition cost guide](https://www.jarviscontracting.ca/guides/home-addition-cost-ontario) goes through the ranges in detail.

Where the models differ is when you learn the number. In design-build, the price firms up as the drawings do. In the two-contract route, you pay for full drawings before any builder prices them. If the bids come in high, you pay the designer again to cut the scope.

## Who applies for the building permit in each model?

You do, legally, though someone usually files for you. Ontario puts it plainly: "It's your responsibility to get building permits" ([Ontario.ca](https://www.ontario.ca/page/your-rights-when-starting-home-renovations-or-repairs)). The Building Code lets the owner or an authorized agent make the application, and the review clock only starts on a complete one (Div. C 1.3.1.3.(5), [2024 Building Code Compendium](https://www.publications.gov.on.ca/301880)).

In Whitby, in Durham Region, Ontario, applications go through the Town's E-Portal at portal.whitby.ca ([Town of Whitby, building permits](https://www.whitby.ca/services-and-payments/building-and-renovating/building-permits/)). In design-build, the firm normally files as your agent and answers the examiner's comments. In the two-contract route, the designer often files, because the comments are about their drawings. Either way, the contract should name who files, who pays the fee and who answers the comments.

The design also decides whether you need a minor variance, whoever draws it. Here's what a residential minor variance costs across Durham Region in 2026:

| Town | Minor variance fee | Source |
|---|---|---|
| Whitby | $1,526 (plus $930 for the Central Lake Ontario Conservation Authority on land it regulates) | [Town of Whitby application](https://media-003-ca.cdn.govstack.com/whitby-ca/media/txxlnw3w/pl-application_minorvariance.pdf) |
| Oshawa | $856 per lot | [Oshawa Committee of Adjustment page](https://www.oshawa.ca/business-development/planning-and-development/development-applications/committee-of-adjustment/) |
| Ajax | $1,638.90 single variance (2025 rate) | [Town of Ajax user fees](https://ajax.ca/wp-content/uploads/2026/03/By-law-61-2024-2025-User-Fees-By-law.pdf) |
| Pickering | $2,500 from 1 July 2026 | [Pickering 2026 user fee schedule](https://corporate.pickering.ca/WebLink/DocView.aspx?id=261891&dbid=0&repo=PICKERING) |
| Clarington | $2,280 residential minor | [Clarington fee by-law](https://weblink.clarington.net/WebLink/ElectronicFile.aspx?docid=455554&dbid=0&repo=Clarington) |

Note: These are application fees only, as published in October 2026; they leave out drawings, survey costs and the months a Committee of Adjustment hearing adds.

## When is an architect plus a general contractor the better choice?

It's the better choice when you want an independent professional on your side. If you'd sleep better with someone who doesn't work for the builder checking the work and the invoices, hire an architect for construction review as well as design.

It also suits you if you already have drawings you like, if you want several bids on identical plans, or if the house needs a specialist designer you've already chosen, say in Whitby's Werden's Plan or Brooklin heritage districts. Design-build suits you better when you want one firm answerable for both the drawings and the build, a budget checked while the design is still cheap to change, and no handoff between two offices.

## What should the contract say in either model?

The same Ontario basics apply to both. The province says a renovation contract should list the contractor's details, a thorough description of the work, warranties, total cost and payment terms, start and finish dates, the payment schedule and deposit, cleanup and the sub-trades. It recommends a deposit of no more than 10% ([Ontario.ca](https://www.ontario.ca/page/your-rights-when-starting-home-renovations-or-repairs)).

The Construction Act adds the 10% holdback ([s. 22(1)](https://www.ontario.ca/laws/statute/90c30)). It covers design as well as building: section 14(3) confirms that an architect's services can give rise to a lien. A contractor's lien expires 60 days after the earlier of publication of substantial performance or the contract being completed, abandoned or terminated ([s. 31(2)](https://www.ontario.ca/laws/statute/90c30)). How the price itself is set is a separate choice, covered in [fixed price vs cost-plus](https://www.jarviscontracting.ca/guides/fixed-price-vs-cost-plus). The checks to run before you sign are in [questions to ask a contractor](https://www.jarviscontracting.ca/guides/questions-to-ask-a-contractor).

One thing neither model gives you on a renovation is a Tarion warranty. The Home Construction Regulatory Authority (HCRA) says renovators "aren't licensed or regulated like new home builders" ([HCRA page on finding a renovator](https://www.hcraontario.ca/resources/finding-a-renovator/)); our [HCRA and Tarion guide](https://www.jarviscontracting.ca/guides/hcra-and-tarion-explained) explains where that line sits.

## How we work

We're design-build, and our contracts are fixed price. Ceara Jarvis leads design through her studio, Juliette Interiors, we draw the permit drawings in-house, and James Jarvis runs construction, all under one contract. The whole project is priced and the contract signed, with a 10% deposit, before design begins, and any change to the price goes through a change order you sign. The steps are on our [design-build](https://www.jarviscontracting.ca/design-build) and [process](https://www.jarviscontracting.ca/process) pages.

The nearest finished job with a full write-up is [Greenwood](https://www.jarviscontracting.ca/projects/greenwood), in east Toronto, roughly 30 km west of our Ajax office. It was a rear extension plus a new top storey with a primary suite, a wet room with a skylight and a den with a walkout balcony. We also enlarged the basement by removing a brick wall and did the full interior design. It took 10 months including design, permits and construction. If you'd rather have an independent architect watching the builder, the two-contract route above is the fair comparison to make.

## Questions

### Is design-build cheaper than hiring an architect and a general contractor in Ontario?

There's no credible published figure showing design-build is cheaper or dearer than an architect plus a general contractor in Ontario. The cost of an addition depends on its size, structure, finishes and what's found inside the walls, and those don't change with the hiring model.

What changes is when you learn the price. Design-build checks cost while the design develops; the two-contract route prices finished drawings, which can mean paying for redesign if bids come in high.

### Who is responsible for mistakes in the drawings with design-build?

With design-build, the firm that drew the plans also builds them, so a gap in the drawings is its problem to fix under the one contract. With an architect plus a general contractor, responsibility depends on two separate contracts, and the designer and builder can each point at the other.

Read the contract either way. It should say who fixes drawing errors and who pays for them.

### Can I still get competing prices if I choose design-build?

Yes, but you compare design-build firms earlier, on their process, past work and a budget range, before final drawings exist. Ontario recommends at least 3 written estimates, and the two-contract route makes that easier because every builder prices identical drawings.

If competitive bids on the same plans matter most to you, an architect plus a general contractor is the better fit.

### Who gets the building permit for an addition in Whitby?

The homeowner is responsible for building permits in Ontario as of October 2026, but the Building Code lets an authorized agent file the application. In Whitby, applications go through the Town's E-Portal, and a design-build firm or your designer usually files as your agent.

Starting work in Whitby before applying costs the greater of $100 or 25% of the application fee under the Town's 2026 fee schedule, so agree in writing who files before demolition starts.

### Does the 10% holdback apply to a design-build contract?

Yes. Section 22(1) of Ontario's Construction Act requires every payer under a contract where a lien may arise to hold back 10% of the value of services or materials supplied, and design is a service to the improvement. Section 14(3) confirms architects' services can give rise to a lien.

So if you sign one design-build contract, or two separate ones, keep 10% back until the lien period has passed.

### Does a design-build firm need an HCRA licence to renovate my house?

A design-build firm typically doesn't need an HCRA licence for renovation work on an existing house. The Home Construction Regulatory Authority (HCRA) licenses new home builders and sellers, and it says renovators aren't licensed or regulated the way builders of new homes are. Coach, laneway and tiny homes generally do need licensing and warranty coverage.

That means a renovation or addition carries no Tarion warranty, whichever model you choose, so the warranty terms in your contract matter.