How much does a second-storey addition cost in Mississauga?

Costs vary a lot based on size and finish level, but second-storey additions typically run in the hundreds of thousands of dollars once you include engineering, permits, roofing, and interior finishing. Ground-level additions are usually cheaper per square foot since they skip the roof removal and re-framing work. Get itemized quotes from at least three contractors before comparing, since some quotes bundle permits and engineering while others treat them as separate line items.

How long does an addition or second storey take to complete?

A full second-storey addition commonly takes several months from permit approval to move-in, and permit approval itself can add weeks depending on how busy the City's building department is. Ground-floor additions tend to move faster. Weather delays roofing and foundation work, so projects started in fall or winter often stretch longer than ones started in spring.

Do I need a permit for a home addition in Mississauga?

Yes. Any addition that changes the structure, footprint, or roofline of your house needs a building permit from the City of Mississauga, and second storeys need stamped structural engineering drawings as part of that application. A contractor who suggests skipping the permit process is a red flag, since unpermitted structural work can cause problems when you sell the house or file an insurance claim.

How do I judge the quality of a contractor's past addition work?

Ask to visit a finished project or at least see close-up photos of the roof-to-wall tie-ins, foundation connections, and insulation detailing, not just the painted final result. Check whether they used the same engineer and permit process they're proposing for you, and ask for references from clients whose additions are now a few years old, since that's when settling, leaks, or drafts from a poor tie-in start to show up.

Home Additions & Second Storeys in Mississauga

Home Additions & Second Storeys in Greater Toronto Area

Adding square footage to a house, whether it's a rear addition, a second-storey pop-top, or a garage conversion, is one of the biggest jobs a homeowner takes on outside of a full custom build. In Mississauga this usually means structural work on the existing foundation or roof, a building permit through the City, engineering drawings for load-bearing changes, and coordination between framers, roofers, electricians, and HVAC trades over several months. We've listed 12 contractors in this category who take on this kind of work, ranging from small design-build firms to larger renovation companies with in-house project managers.

What this work actually involves

A second-storey addition means removing or reinforcing the existing roof structure, building new exterior walls and a new roof, then tying the whole envelope back together with insulation, siding, and windows before interior finishing starts. A ground-level addition is usually simpler structurally but still needs a new foundation, footings, and a tie-in to the existing house that doesn't create leaks or settling issues down the road. Both require a permit, and second storeys almost always need a structural engineer to confirm the existing foundation can carry the extra load.

What to look for in a contractor

Ask to see a full permit and engineering package from a past project, not just photos of finished rooms. Find out who pulls the permit (it should be the contractor or a licensed sub, not left to you), how they handle unexpected foundation or framing issues once walls are opened up, and whether the quote is fixed-price or cost-plus. Get a clear payment schedule tied to completed stages of work, not lump sums up front, and confirm they carry liability insurance and WSIB coverage for any subs on site.

Our ranking weighs licensing and insurance, verified reviews, years doing this specific type of structural work, and responsiveness to quote requests, not just star ratings. See the full breakdown and scoring criteria on our methodology page, and compare all 12 contractors head to head in our ranked guide to Mississauga renovation contractors.

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All home additions & second storeys in Mississauga, ranked by score and relevance

We found 12 businesses offering home additions & second storeys in Mississauga; 7 met the criteria for the scored directory. The order weighs each business's overall score by how much of its reviewed work is home additions & second storeys, so a lower-scored specialist can rank above a higher-scored generalist.

Hudson Restoration GTA (HQ)

4.9(242)✓ Google-verified

When a pipe bursts or basement floods, Hudson Restoration answers the phone and shows up ready to move fast. Reviewers consistently mention the same handful of names-Jerry, Norm, Siobhan, Meron, Ben, and others-who treat catastrophic water damage like a solvable problem, not an opportunity to pad the bill. Teams finish repairs within days or weeks instead of months, keep owners informed with daily updates, and leave sites cleaner than when they arrived. The company handles flooded condos, heritage homes, rental units, and apartment buildings across the GTA and beyond, from initial water removal through drywall, flooring, and painting. Reviewers who had another contractor fail or oversell work first say Hudson's approach-honest, methodical, willing to bend on scope-turned a disaster into relief. Staff work around occupied units and tight schedules without complaint, and the emphasis on communication means homeowners feel less anxious, not more.

Water Damage Restoration ServiceInterior Construction ContractorHome Builder

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HandyBros | Home Renovations & General Contracting

4.9(153)✓ Google-verified

Rob and the HandyBros team deliver consistent, high-standard work across kitchens, bathrooms, basements, and exterior projects. Reviewers consistently highlight transparent pricing, reliable scheduling, clear communication via text and site visits, and attention to detail in finishing. The crew (including named specialists Yi on tiling, Eddie on bathroom work, Gabe, Ron, and Eric) earns praise for professionalism, staying on budget, and willingness to fix issues or complete work abandoned by other contractors.

Kitchen RenovationEmergency & Quick-Turnaround RepairsHome Additions & Second Storeys

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Ace Build Contracting

4.9(147)✓ Google-verified

Reviewers consistently report smooth projects with strong communication: weekly photo updates, same-day responses, and clear pricing for any changes. Leadership by Abbi and the broader team earned trust even from busy homeowners managing major additions and renovations. Work spans kitchens, bathrooms, legal basements, and full-home extensions in Mississauga, Etobicoke, Burlington, and Toronto, with craftsmanship praised for framing, drywall, cabinetry, tile, and finishes. Projects stay on timeline and budget, sites remain clean, and permits and inspections are handled as part of the service. Even a kitchen cabinet manufacturer trusted them as partners. The only concrete detail missing from reviews is response to budget overruns or delays-none were mentioned across 18 reviews, suggesting either rare occurrence or happy resolution.

Interior Construction ContractorKitchen RenovationHome Additions & Second Storeys

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Real Brothers Construction Limited

5.0(30)✓ Google-verified

Real Brothers delivers consistently on renovation and repair work across the GTA. Reviewers repeatedly praise their clear upfront pricing, punctual job completion, and hands-on approach where the owners do the work themselves rather than subcontracting. Communication through the project (daily texts, weekly site reviews) sets them apart, as does their focus on protecting your home and leaving clean worksites.

Emergency & Quick-Turnaround RepairsHome Additions & Second StoreysBathroom Renovation

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79 low data

Leda Restoration & General Contracting

4.6(39)✓ Google-verified

Water damage floods or fire emergencies, Leda dispatches crews within hours and keeps owners informed at every step. Tim, Andrew, Johnny, Mike, and Nunno handle everything from assessment through reconstruction, managing insurance coordination and rebuild details with visible care for cleanliness and final results.

Water Damage Restoration ServiceEmergency & Quick-Turnaround RepairsInterior Construction Contractor

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72 low data

Crown Constructions

5.0(11)✓ Google-verified

Crown Constructions delivers full-house transformations with consistent five-star ratings. Reviewers praise custom-built homes that feel personal, kitchen finishes that impress, and a team that stays transparent through supply delays and keeps clients updated throughout.

Custom Carpentry & FinishingHome BuilderKitchen Renovation

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64 low data

TRUbuild Custom Homes and Renovations

4.5(15)✓ Google-verified

JT and the TRUbuild team earn consistent five-star praise for custom homes and full renovations in the GTA. Reviewers highlight their detail-focused approach, willingness to handle complex scope changes mid-project, and transparent cost negotiation with trades-though one reviewer flagged price and quality concerns.

Home BuilderCustom Home BuilderHome Additions & Second Storeys

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Common questions about home additions & second storeys

How much does a second-storey addition cost in Mississauga?: Costs vary a lot based on size and finish level, but second-storey additions typically run in the hundreds of thousands of dollars once you include engineering, permits, roofing, and interior finishing. Ground-level additions are usually cheaper per square foot since they skip the roof removal and re-framing work. Get itemized quotes from at least three contractors before comparing, since some quotes bundle permits and engineering while others treat them as separate line items.
How long does an addition or second storey take to complete?: A full second-storey addition commonly takes several months from permit approval to move-in, and permit approval itself can add weeks depending on how busy the City's building department is. Ground-floor additions tend to move faster. Weather delays roofing and foundation work, so projects started in fall or winter often stretch longer than ones started in spring.
Do I need a permit for a home addition in Mississauga?: Yes. Any addition that changes the structure, footprint, or roofline of your house needs a building permit from the City of Mississauga, and second storeys need stamped structural engineering drawings as part of that application. A contractor who suggests skipping the permit process is a red flag, since unpermitted structural work can cause problems when you sell the house or file an insurance claim.
How do I judge the quality of a contractor's past addition work?: Ask to visit a finished project or at least see close-up photos of the roof-to-wall tie-ins, foundation connections, and insulation detailing, not just the painted final result. Check whether they used the same engineer and permit process they're proposing for you, and ask for references from clients whose additions are now a few years old, since that's when settling, leaks, or drafts from a poor tie-in start to show up.