Basement Apartment Self-Survey

For a permit, the building department needs a heat loss calculation for the new unit and proof that your furnace can carry both units. If you have no drawings, this survey replaces the site visit for most houses. It takes about 25 minutes with a tape measure and your phone. As you go, the bar at the bottom tells you whether what you have given us is enough, or whether we will need to come out.

1. The project

Two minutes. Tells us which calculation applies.

What are you building? *

A basement apartment shares the house’s foundation; a garage or garden suite has its own walls and roof. The calculation is different.

Basement apartmentGarage conversionGarden suite / laneway houseAddition to the house

Municipality *

Sets the outdoor design temperature from the Building Code (SB-1). Tell us the town, not the region.

Property address *

Goes on the permit documents.

Bedrooms in the suite *

The Code sets the suite’s ventilation rate by bedroom count (OBC 9.32.3.3).

Bachelor / 0123

Is this space heated by the house furnace today? *

A basement the furnace already heats adds much less load than a cold garage.

Yes, it has registers / is warm in winterPartlyNo, unheated

2. Measure the suite

A tape measure. Inside dimensions, wall to wall.

Suite length (feet) *

Measure inside, wall to wall, the long way.

Suite width (feet) *

Inside, wall to wall, the short way. If the suite is L-shaped, give us the two rectangles in the notes.

Ceiling height (feet) *

Floor to underside of joists or finished ceiling.

Foundation wall showing above ground outside (feet)

Basement apartments only. Measure outside from the ground to the top of the concrete at two corners and give us the average. Below-ground wall loses heat differently from wall in the air.

How many sides of the suite are exterior walls? *

A garage conversion sharing one wall with the house has three exterior sides.

4321

3. Walls, windows, ceiling

Most of the heat loss is here. Photos beat guesses.

What is in the exterior walls? *

Take the cover off an outlet on an exterior wall and photograph what you see, or photograph any open section. We will read the R-value from it.

Nothing / bare concreteFibreglass batts in a stud wallRigid foam boardSpray foamDon’t know

Wall R-value if you know it

Only if you have it from a renovation receipt or an insulation label.

What is above the suite? *

A heated house above means the ceiling loses nothing. An attic or open air means it loses a lot.

The heated houseAtticFlat roofGarage or unheated space

Ceiling R-value if you know it

Only where there is an attic or roof above.

Total window area (square feet) *

Width x height of each window glass-plus-frame, added up. A typical basement hopper window is about 2 x 1.5 ft = 3 ft2.

ft2

Window type *

Glass is 25-45% of the load. Single pane roughly doubles it.

Single paneDouble paneDouble pane low-E (newer, often a faint tint)Triple paneDon’t know

Exterior door area (square feet) *

A standard door is 20 ft2. Glass patio door: measure it.

ft2

Floor *

Slab on grade and a basement floor are both ground contact; a garden suite on piers is a floor over outdoor air.

Concrete basement floorConcrete slab on gradeWood floor over crawlspace or piers

4. The house it is attached to

From your MPAC assessment or the listing when you bought it.

Above-grade floor area of the house (square feet) *

From your tax assessment (MPAC) notice or listing. It is used to estimate the house’s own heating load.

ft2

When was the house built? *

The estimate of the house’s load depends mostly on era of construction.

Before 19601960-19791980-19992000-20112012 or later

Bedrooms in the main house *

The main dwelling keeps its own ventilation requirement.

12345+

5. The furnace

One photo of the nameplate answers the question most people are asking.

What heats the house now? *

Gas furnacePropane furnaceOil furnaceBoiler (hot water radiators or in-floor)Electric baseboardsHeat pump

Photo of the furnace / boiler nameplate *

The label on the side of the unit gives the input Btuh and the AFUE or output. This single photo decides whether your furnace can carry the suite.

Phone photos are fine. Several at once is fine.

Input (Btuh) from the nameplate

Type it if you can read it; we will check it against the photo.

Btuh

AFUE % from the nameplate

Often on the yellow EnerGuide label.

Output (Btuh) if the nameplate gives it

Some labels say ‘output’ or ‘bonnet capacity’ directly.

Btuh

Approximate age (years)

A unit near end of life changes the advice even if it carries the load.

years

Are there supply registers in the suite now? *

Tells us whether the existing ducts already reach the space.

Yes, severalOne or twoNone

6. Photos

Every photo lowers the chance we need to visit.

Photo of each exterior side of the suite from outside *

Shows the exposed foundation height, windows and doors.

Phone photos are fine. Several at once is fine.

Photo of each room inside *

Shows ceiling type, windows, and finish.

Phone photos are fine. Several at once is fine.

Photo inside an exterior-wall outlet box, or any opening in the wall

Shows the insulation. The single most useful photo after the nameplate.

Phone photos are fine. Several at once is fine.

Anything else

L-shaped rooms, a walk-out, a cold room, a plan you have on paper.

Confidence: 0 / 100Fill in the form to see whether a visit is needed.

Basement Apartment Self-Survey

1. The project

2. Measure the suite

3. Walls, windows, ceiling

4. The house it is attached to

5. The furnace

6. Photos

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