Chapter 3. Roof, Windows and Site Utilities. Attic or full second storey: which to choose for a house in 2026.

A key question when designing a two-storey home: attic floor or full second storey? Each has its strengths, and the right choice depends on budget, layout, climate and personal taste. Let's analyse both with calculations for the Leningrad Region.

Definitions

Attic floor (mansard) — living space under the pitched roof where walls are partly formed by the roof. Sloped ceilings, knee walls 0.8–1.5 m, roof windows. Per SNiP, the room counts as habitable if ceiling height ≥ 2.5 m covers at least 50% of the area.

Full second storey — full-height walls (2.5–3.0 m) with horizontal ceiling, cold attic above. All walls vertical, all corners square.

Cost comparison (60 m² upper level)

Attic seems cheaper at first glance. Detailed numbers:

Difference is about 35 000 ₽ — under 4%. The attic-savings idea is a myth: cheaper walls are offset by expensive insulated roof and roof windows.

Usable area: attic loses 15–30%

In an attic significant area has ceiling height under 1.5 m — not usable for full living.

• Attic: 42–50 m² of 60 built = 15–30% loss

• Full storey: 60 of 60 m² = no loss

Real cost per usable m²:

• Attic: 1 085 000 / 46 = 23 600 ₽/m²

• Full storey: 1 120 000 / 60 = 18 700 ₽/m²

Full storey is 20–25% cheaper per usable m².

Insulation

Attic — entire roof insulated: slopes, gables, junctions. 200–250 mm between and below rafters, perfectly sealed vapour barrier, 40–50 mm vent gap. Insulated area 150–180 m².

Full storey — only the attic floor (horizontal). 200–300 mm rolled out flat, simple vapour barrier, ridge and eave vents. Area 60–70 m². 2–3× simpler and cheaper. Cold attic is the most reliable and proven solution.

Aesthetics

Here the attic wins. Sloped ceilings create cosy intimacy. Roof windows pour overhead light no standard room can deliver. A full storey is standard rectangular rooms — comfortable but without that special atmosphere.

Resale value

Full storey is almost always valued higher than an attic — buyers count m² by floor (60 vs 46), perceive attics as 'lofts', and associate condensation/leak/overheat risks with attics.

In the Leningrad Region climate

For attic: steep 35–45° slopes (needed for snow) yield high ceilings; lower building height reduces wind load (relevant near the Gulf of Finland).

For full storey: cold attic eliminates condensate risk (dangerous in our damp climate); simpler ventilation; heat loss through attic roofs causes snow melt and icicle formation on eaves.

Recommendations

In most cases for the Leningrad Region we recommend a full second storey with cold attic as the more practical and reliable solution. Attic remains a great choice for those valuing the special atmosphere and ready to invest in top-quality insulation.

StroyInvest24 designs and builds houses with both attic and full second storey — we'll help you decide, cost both options and build a home that will please for decades.

See also

• One-storey vs two-storey house

• Roof and mansard insulation

• Roof design for a private house

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