The Bible does not give a specific number of windows and doors for Noah’s Ark, but it states there was one door and one window (or opening) near the top. The Book of Genesis (6:16) says: “You shall make a window for the ark, and finish it to a cubit from the top; and set the door of the ark in its side.” This is the only reference in the original text. However, modern UK building regulations for homes require far more specific glazing and entry points. For example, Part B of the Building Regulations mandates at least one door for escape and a minimum window area for emergency egress in habitable rooms (GOV.UK, 2026).
The decision on how many windows and doors a home needs depends on room use, floor area, and escape requirements. For a typical three-bedroom house, you might have 8–12 windows and 2–3 external doors. But the Ark’s single door and single window were designed for a completely different purpose, flood safety, not daily living. In modern UK homes, the number is driven by energy performance and fire safety, not theology.
One door was specified in the original text
Genesis 6:16 explicitly mentions a single door set in the side of the Ark. This was the only entrance and exit for all animals and people. In contrast, a standard UK home under Building Regulations Part M must have at least one accessible entrance door with a minimum clear opening width of 775mm (GOV.UK, 2026). Many homes have a front door, back door, and sometimes a side door or patio doors. The Ark’s single door would fail modern accessibility standards for a dwelling of its size.
One window or opening near the top
The same verse describes a window “finished to a cubit from the top,” likely a single opening running around the top of the structure. This provided light and ventilation. Modern UK glazing standards are far more demanding. Approved Document L requires windows to have a minimum U-value of 1.4 W/m²K for replacement units (GOV.UK, 2026). A single open top would lose heat rapidly. Energy Saving Trust notes that double glazing can save around £195 per year on heating bills (Energy Saving Trust, 2026). The Ark’s design prioritised flood survival, not thermal efficiency.
Modern homes require many more openings
Building Regulations Part F demands adequate ventilation, often requiring trickle vents or openable windows in every habitable room (GOV.UK, 2026). A typical three-bedroom house has 8–12 windows plus 2–3 external doors. The Ark, with just one door and one window, would not meet these standards. For comparison, a modern home must also have at least one window per bedroom for emergency escape under Part B. The Ark’s single window near the top would be impossible to reach in a fire.
A worked example
Glazing is standard-rated for VAT at 20%. The zero rate for energy-saving materials covers insulation, heat pumps and solar panels; HMRC names secondary and double glazing as excluded (VAT Notice 708/6). The Energy Saving Trust estimates this saves roughly £195 per year on heating bills for a gas-heated property. The payback period on the glazing alone is therefore around 44 years, but the real value comes from added comfort, reduced condensation, and a potential increase in the home’s EPC rating. A full set of 10 windows plus a back door and front door transforms a draughty property. For the door specifically, Part B of the Building Regulations requires it to open outward for fire escape, a detail many homeowners overlook when choosing a style.
| Item | Figure |
|---|---|
| Upfront cost after grants | £8,500 |
| Yearly savings | £195 |
| Payback period | 44 years |
| 25-year lifetime savings | £4,875 |
What homeowners often get wrong
The most common mistake is assuming more windows always improve a home’s energy rating. This overlooks the balance between natural light and heat loss in a typical UK property.
- Believing double glazing alone solves condensation The misconception is that new windows stop all moisture. The right answer is that trickle vents and adequate ventilation are essential, without them, mould can form and void your warranty, costing hundreds in repairs.
- Thinking a single door is enough for fire safety Many assume one front door meets regulations. In fact, Part B of the Building Regulations often requires a second means of escape, such as a back door or French doors, especially in open-plan layouts, a missed requirement can delay a sale.
- Assuming all windows must be replaced at once Homeowners often feel pressured to do the whole house. The right approach is to prioritise north-facing or draughty rooms first, a phased replacement over two years can save £1,500 in upfront costs while still improving the EPC rating.
Quick reference
- A typical UK three-bedroom semi-detached home has 8 to 12 windows and 2 to 3 external doors.
- Part B of the Building Regulations requires at least one accessible entrance door and a minimum window area for emergency escape in every habitable room.
- Energy Saving Trust data shows that replacing single glazing with A-rated double glazing saves around £195 per year for a gas-heated semi-detached home.
- Glazing is standard-rated for VAT at 20%. The zero rate for energy-saving materials covers insulation, heat pumps and solar panels; HMRC names secondary and double glazing as excluded (VAT Notice 708/6).
- A single door on the Ark was designed for flood safety, not daily living, modern homes need multiple access points for fire escape and ventilation.
Frequently Asked Questions
The Bible states one window and one door. Genesis 6:16 mentions 'a window for the ark' and 'set the door of the ark in its side.'
Genesis 6:16 says to make a window near the top and set a single door in the side. This is the only reference in the original text.
A typical UK three-bedroom house has 2–3 external doors, while the Ark had just one. Building Regulations Part M requires at least one accessible entrance door.
