New build inspection · Attic and insulation
Attic and insulation defects in a new build
The attic is the easiest place in a new house to find real defects, because almost nothing up there is hidden and almost nobody looks.
What goes wrong with attic and insulation in a new build?
Reviewed · 2026-09-03The attic is the easiest place in a new house to find real defects, because almost nothing up there is hidden and almost nobody looks.
Why it matters
Attic and insulation in a new home
Insulation is sold by depth and installed by a crew with a blower hose. Getting the right average depth across a large attic is genuinely difficult, and the corners, the edges above exterior walls and the areas behind obstructions are consistently thin.
The attic is also where several other trades finish their work badly. Bathroom and kitchen exhaust ducts are supposed to run to the outside; when they are left dumping into the attic, they deposit warm wet air into the coldest part of the house all winter. That is how a two-year-old home grows mould on its sheathing.
In Calgary the consequences arrive fast. Heat escaping into the attic melts snow on the roof, the melt refreezes at the cold eave, and ice damming pushes water back under the shingles. Chinooks make the melt-freeze cycle happen repeatedly rather than once a season.
Best moment to look
Pre-possession walkthrough
Open the attic hatch at the walkthrough with a flashlight, then look again after the first heavy snow for the melting patterns that reveal heat loss.
In Alberta
Alberta energy code requirements have pushed new home insulation levels well above what older Calgary housing stock carries, which is one of the genuine advantages of buying new. That only holds if the insulation was actually installed to the specified depth everywhere. Ask for the insulation certificate or the depth specification for your home and compare it with what you can see in the attic. Insulation and exhaust venting defects fall under the workmanship coverage of the Alberta New Home Warranty, so the first winter is the time to act.
How it should be built
What correct looks like
A correctly built attic edge
Insulation holds full depth over the exterior wall, a baffle keeps the soffit air path open, and the bathroom fan ducts through the roof rather than into the attic.
The flags
What to look for
Each item lists what the defect is, how to spot it without tools, and the stage of construction when it is still visible. None of this replaces a licensed inspector. It makes you a useful witness on your own site.
01Insulation shallower than specified, especially at the edges
Comfort and costWhat it is. Blown insulation is specified to an average depth, and the perimeter above exterior walls is the hardest place to reach. Thin edges cause cold ceilings, ice damming and the highest heating bills in the house.
How to spot it. Look for the depth markers the installer is required to leave on the trusses. Check the reading near the middle and then near the eaves; a large difference is the finding.
Visible at: Pre-possession walkthrough
02Missing or crushed ventilation baffles
Water and envelopeWhat it is. Baffles hold insulation back from the soffit vents so outside air can wash the underside of the roof. Without them the insulation blocks the vents, the attic stops venting, and moisture accumulates.
How to spot it. Shine a light toward the eaves. You should see cardboard or foam channels keeping a clear air path from the soffit into the attic at every rafter bay.
Visible at: Pre-possession walkthrough
03Bathroom or kitchen fan venting into the attic
Water and envelopeWhat it is. An exhaust duct that terminates in the attic instead of through the roof or wall pumps moist air into the cold space every time the fan runs. It is one of the most damaging defects found in new homes and one of the easiest to see.
How to spot it. Trace every flexible duct in the attic. Each must connect to a vent through the roof or the gable, with a clamped joint. A duct lying loose, or one that has slipped off its collar, is the finding.
Visible at: Pre-possession walkthrough
04Attic hatch not insulated or weather stripped
Comfort and costWhat it is. The hatch is a hole in the insulated ceiling. Uninsulated and unsealed, it leaks warm moist air continuously and frosts over on the attic side.
How to spot it. Look at the top of the hatch cover. It should carry insulation matching the attic and sit on a compressible seal, with something holding it down.
Visible at: Pre-possession walkthrough
05Air sealing gaps at penetrations
Water and envelopeWhat it is. Every plumbing stack, wire, light fixture and duct through the ceiling is an air leak. Warm indoor air escaping through them carries moisture into the attic and shows as frost on the nails.
How to spot it. Look where pipes and wires come through the attic floor. You want sealant or foam around them. In winter, frost on nail points or on the sheathing above a specific spot marks the leak.
Visible at: First winter
06Ice damming and uneven snow melt
Water and envelopeWhat it is. A well-insulated roof keeps snow on it. Bare patches, icicles and ice ridges at the eaves show that heat is escaping into the attic and melting snow from below.
How to spot it. After a snowfall, photograph the roof from the street. Look for melted stripes, bare areas over rooms and heavy icicles along one section of eave.
Visible at: First winter
Put it in writing
Questions for the builder
Ask these by email rather than on site. A written answer is a record, and a builder who answers clearly in writing is telling you something useful about how the rest of the build will go.
- What insulation value is specified for the attic, and can I see the certificate?
- Are all bathroom and kitchen exhausts ducted to the exterior, and where do they terminate?
- Are baffles installed at every rafter bay?
- Is the attic hatch insulated and weather stripped as standard?
FAQ
Questions about attic and insulation
Installers are generally required to leave depth markers on the trusses showing the target. Open the hatch, look at several markers across the attic, and compare the middle with the area above the exterior walls. Uniform depth matching the marker is what you want. A deep centre and thin edges is a common and consequential finding.
Every shower sends warm, moisture-laden air into the coldest part of the house, where it condenses on the underside of the roof sheathing. Over a Calgary winter that produces frost, then water, then mould and eventually damaged sheathing. It is inexpensive to fix and expensive to ignore, and it is visible with a flashlight from the attic hatch.
Icicles form when heat escaping through the roof melts snow that then refreezes at the cold eave. A little is normal in a chinook climate where melting happens anyway. Consistent heavy ice at one section of eave, bare melted patches over specific rooms, or water backing up under the shingles all point to insulation or air sealing problems in the attic below that spot.
Source note
- Sources
- Alberta New Home Warranty program information
- National Building Code, Alberta Edition, as adopted for the permit in force
- City of Calgary building inspection and lot grading information
- Health Canada radon guidance for homeowners
- Jurisdiction
- Alberta, with Calgary-specific notes
- Applies to
- New residential construction purchased from a builder.
- Last reviewed
- 2026-09-03
- Limitations
- General guidance written for buyers, not a code interpretation and not a substitute for a licensed home inspector or a professional engineer. Code requirements depend on the edition in force when the permit was issued. Warranty periods and coverage depend on your own warranty certificate.
- What you should verify
- The requirements that applied to your permit, the coverage periods on your warranty certificate, and any defect with a licensed inspector before you rely on it in a claim.
Work with REP YYC
Bring your own representative to the walkthrough.
The builder's sales staff are paid to sell the builder's lots. REP YYC agents are paid by the builder too, but they work for you: lot choice, contract terms, incentives and the possession timeline. No cost to the buyer.