How to Add a Second Storey
to a Bungalow

The bungalow second-storey addition is one of the most common big projects in Ottawa right now. Families who bought a 1,100 square foot Alta Vista or Manor Park bungalow years ago now need three more bedrooms but can't stomach the idea of selling and moving to Carp.

The math kind of works. You stay in your school zone, your kids keep their friends, and you double your square footage on a lot you already own. The problem is that "adding a second floor" is one of the more complicated things you can do to a house. People underestimate it, and that's where projects go off the rails.

Here's the real process from foundation review to move-back-in, and the factors that drive what it costs based on what we're actually quoting and building right now.

Phase 1: Can Your House Even Take It?

Before you draw a single line, the foundation and existing framing have to be assessed. A 1955 bungalow was designed to support a roof and a single floor, not a 2,000-pound load every 16 inches across a new floor system above.

The structural engineer (paid by you, billed as a feasibility report) checks:

1. Foundation type and condition (poured concrete, concrete block, or rubble; rubble is the worst news)
2. Foundation wall thickness and footing depth (footings need to be below frost line, 1.2 m / 4 feet, in Ottawa)
3. Ground floor wall framing (2x4 vs 2x6, stud spacing, header sizes)
4. Soil bearing capacity (sometimes a separate soil test is needed)
5. Existing first-floor joists (will they carry the new floor above, or are point loads coming down?)

The likely outcome on an Ottawa bungalow built 1948-1980: foundation is fine, but selective reinforcement is needed. Common interventions, each a separate line in the budget: underpinning sections of the foundation (priced per linear foot), adding a steel beam in the basement to carry new point loads, and replacing 2x4 first-floor walls with 2x6 where the load path requires it. How much of this your house needs is the single biggest swing in the early budget.

If the engineer's report says "this house is not a candidate for a second storey," they're saving you from a major cost overrun. Believe them.

Phase 2: BCIN Drawings and the Permit Set

For a second-storey addition you need a full set of permit drawings stamped by a BCIN-certified designer (House category, minimum) and a P.Eng for any structural elements. The drawing set typically includes:

• Site plan showing setbacks, lot coverage, height (Ottawa zoning permits 8.5-11 m height in most R1/R2 zones)
• Existing and proposed floor plans
• Elevations (all four sides, existing and proposed)
• Building section showing the new floor structure, insulation, vapour barrier
• Structural drawings showing beam sizes, post locations, foundation reinforcement
• Mechanical drawings for HVAC, plumbing, electrical changes
• Energy efficiency design summary (SB-12 compliance)

The design package is a meaningful line item on a typical 1,000-1,400 square foot addition, driven by the size of the addition and the complexity of the structural work. This is where homeowners try to save money by skipping the BCIN and using "a guy who draws plans." The City of Ottawa won't accept unstamped drawings for a structural addition. You'll just lose 6 weeks before resubmitting properly.

This is exactly the work our in-house BCIN-certified design team handles on every home addition project: drawings, permit submission, and the back-and-forth with the plans examiner.

Phase 3: Permit Submission and Review

Submission is online through the MyServiceOttawa portal. City of Ottawa permit fees for a second-storey addition are calculated on the declared construction value, so the larger the addition, the higher the fee. The City's minimum permit fee is $117, but you'll be well above that on a real addition.

Review timeline: 6-12 weeks for a residential addition in 2026. Plan examiners come back with comments, drawings get revised, resubmitted, and (usually) approved on the second pass. Building permit issued.

OBC compliance for a second-storey addition specifically requires:

• SB-12 energy efficiency package (one of 5 prescriptive packages or performance compliance)
• Egress windows in every bedroom (minimum 0.35 m² openable area, no dimension less than 380 mm)
• Fire separation if the addition creates a second dwelling unit (it usually doesn't, but if you're going for a basement legalization at the same time, this matters)
• Smoke and CO alarms hardwired with battery backup, interconnected, on every floor
• Stair geometry (rise 125-200 mm, run 255-355 mm, headroom 1950 mm minimum)

Phase 4: Removing the Roof

This is the day everyone remembers. Roof comes off in 1 day if the weather cooperates. The crew strips shingles, tears out the trusses or rafter system, and hauls everything to the dumpster.

The challenge: you now have an open house. Even with a tarp, a hard rain in the wrong week causes water damage to the existing first floor. The crew installs a temporary roof structure (engineered tarp system or temporary plywood deck with poly) the same day, but it's not perfect.

Critical sequencing:

1. Move out everything you care about from the upper rooms (electronics, clothes, photos) the week before.
2. Disconnect HVAC ductwork serving the existing attic.
3. Remove the old chimney if it was an unused brick stack (most Ottawa bungalows have one to deal with).
4. Strip shingles, tear out roof structure.
5. Install temporary weather protection same day.

Pick a weather window. Late May through early September is the lowest-risk period in Ottawa. Roof-off in November is asking for trouble.

Phase 5: Framing the New Floor

The new second floor framing typically uses engineered I-joists (TJI) at 16" or 19.2" on centre, sized by the engineer. Span tables don't apply here. The engineer specifies the joist depth and series based on the design loads and the rooms above.

Sequence on a typical Ottawa bungalow:

1. Sister or replace any existing top-of-wall plates that need it.
2. Set the new rim board around the perimeter.
3. Install I-joists across the span (typically 4-6 hours for a 1,200 square foot floor).
4. Sheet the new floor with 3/4" tongue-and-groove subfloor, glued and screwed.
5. Frame the new perimeter walls (2x6 standard for Ottawa to hit insulation requirements).
6. Frame interior partitions.
7. Set roof trusses or stick-frame the new roof (trusses are faster and cheaper, stick-frame allows for vaulted ceilings).
8. Sheath the roof, install ice and water shield, then dry-in with synthetic underlayment.

From roof-off to fully dried-in shell: typically 3-5 weeks if no weather delays.

Phase 6: Weatherproofing and the Building Envelope

The exterior weather barrier is what keeps the project from becoming a mould investigation in 2031. Real envelope work, properly sequenced:

• House wrap (Tyvek, Typar, or membrane equivalent) installed shingle-style, all seams taped
• Window flashing tape integrated with house wrap
• Windows installed with proper sill pan, side flashing, head flashing, and end-dam at jambs
• Continuous exterior insulation if the SB-12 package requires it (typically 1-1.5" of rigid foam)
• Strapping for rain screen detail (1 x 3 vertical strapping creates a drainage and ventilation gap behind cladding)
• Cladding (siding, brick veneer, or board-and-batten, matching the existing or doing a complete re-clad)

The envelope is not where you save money. A leaky envelope on a second-storey addition shows up as ice dams, condensation in the wall cavity, and stained drywall on the ceiling below within 3-5 years.

Phase 7: Mechanical Tie-Ins (Where Most People Underestimate)

Adding 1,200 square feet of conditioned space upstairs means your existing furnace and AC need to handle the new load. The HVAC contractor does a Manual J calculation and usually concludes:

• Furnace upgrade or zoned addition: The 60,000 BTU furnace from 2008 doesn't have capacity. Upgrade to 80,000-100,000 BTU, or add a zoned system.
• AC upsize: 2-ton becomes 3-ton, or two systems with a smaller upstairs unit.
• Ductwork extension: New supply and return runs to every upstairs room.
• Plumbing stack extension: The 3" main vent stack continues up through the new roof.
• Electrical service upgrade: Existing 100A panel often needs to go to 200A, plus an ESA permit.

The mechanical scope on a second-storey addition is half the surprise budget. If your contractor's quote shows a single token line for "HVAC adjustments," ask for the load calc. A full second-floor load is several times that.

Phase 8: Interior Finish

Once the shell is dried-in and rough-ins are inspected, the interior moves the same as any new construction:

• Insulation (mineral wool or fibreglass batts in walls, blown cellulose or batts in ceiling, vapour barrier on the warm side)
• Drywall (1/2" walls, 5/8" ceilings, taping and three coats of mud)
• Prime and paint
• Trim and doors
• Flooring (hardwood typically, occasionally LVP for kid bedrooms)
• Bathroom finishes: tile, vanity, fixtures (see our bathroom budget article)
• Lighting, switches, outlets
• Final inspection

What Drives the Cost of a Bungalow Pop-Up

A second-storey addition is one of the larger residential projects in Ottawa, and the budget moves with the size of the new floor, the finish level, and how much structural reinforcement the existing house needs. Rather than a single number, the right way to read a proposal is line by line. These are the scope blocks that make up the build, roughly in order of their share of the total:

• Design and permits (BCIN drawings, engineering, City permit)
• Foundation reinforcement (varies most with foundation condition)
• Demo and structural (roof removal, beams, load path)
• Framing and shell (the single largest block, scales with square footage)
• Mechanical (HVAC, plumbing, electrical)
• Insulation and drywall
• Interior finishes (flooring, paint, trim, set by finish level)
• Bathroom(s) (the biggest finish-level swing per room)
• Cladding/exterior re-clad
• Project management and contingency

Budget separately if you're also redoing the existing first floor (most clients do, since the kitchen and entry will look dated next to the new upstairs). We set every one of these as a written line item with material allowances, so you can see exactly where the money goes and adjust scope before signing.

Timeline: 16-20 Weeks Active Construction

From permit-in-hand to keys-in-hand:

• Foundation/structural prep: 2 weeks
• Roof off, frame floor and walls, dry-in: 5-6 weeks
• Mechanical rough-in and inspections: 3 weeks
• Insulation, drywall, taping: 3 weeks
• Finishes, flooring, fixtures: 4-5 weeks
• Punch list, final inspection: 1-2 weeks

Plus 4-7 months of design and permit before any of that. So from "we want to do this" to "we're sleeping in the new master": 11-15 months total.

Where to Live During

You cannot live in the house with the roof off. The first 6-8 weeks (roof off through dried-in shell) require you to be out. Options Ottawa families use:

• Furnished rental (3-month minimum lease): usually the most economical option for a multi-month build, and the figure to plan around for a 3-bedroom.
• Family member's house (free, but tests relationships)
• Extended stay hotel (Marriott Residence Inn, Element Ottawa): convenient but the nightly rate stops making sense past about four weeks.
• Airbnb monthly: 30-day stays are often discounted 30-40%, which can make them competitive with a short-term lease.

Some homeowners move back in once the upstairs is dried-in even though it's not finished. Your contractor will tell you when that's safe (usually after Phase 6, before Phase 7). Living through Phase 7-8 is doable if you have a working ground floor and the dust is contained upstairs.

A second-storey addition is a serious project. The ones that go well start with a real engineer's review, a stamped BCIN drawing set, a fixed-price contract, and a contractor who's done at least 5 of them in Ottawa. Skip any of those four and you're rolling the dice on a project worth more than most people's first house.