Good ventilation stops damp, mould, cooking smells and stuffy rooms. In Lahore houses the main needs are kitchens, toilets and basements. In shops, restaurants and offices, exhaust and fresh air also affect comfort, safety and how hard the AC has to work.
What is included
| Item | What it covers |
|---|---|
| Toilet and bath exhaust | Wall or ceiling fans with ducts to outside, sometimes linked to the light switch |
| Kitchen hood and exhaust | Hood over the cooking range, duct to outside, grease filters |
| Basement ventilation | Supply and exhaust fans, ducting, sometimes linked to sensors |
| Fresh air supply | Filtered outside air into AC rooms or offices |
| Commercial kitchen exhaust | Large hoods, grease ducts, roof fans, make-up air |
| Duct work | Sizing, routing, supports, sealing, outlets with cowls or louvres |
When you need it
- Internal toilets or kitchens with little window area
- Basements, which have limited natural airflow
- Open kitchens where smells spread into lounges
- Restaurants, cafes and food outlets
- Offices and clinics with sealed glazing and AC
- Laundries, gyms and any space with moisture or heat
LDA rules you should know
The LDA Building and Zoning Regulations (LDA regulations) say:
- Toilets, water closets, urinal stalls and bathrooms must have daylight and ventilation through one or more openings in external walls, with at least 2 sq ft of opening per fixture.
- Kitchens, toilets and bathrooms may instead use internal air wells for light and ventilation, subject to minimum sizes linked to building height.
- Kitchens must have a minimum floor area of 50 sq ft and a minimum width of 6 ft.
- Habitable rooms need glazing of at least 8% of floor area unless mechanical ventilation is provided.
- In non-residential buildings, ducts must be non-inflammable and supported, penetrations sealed against flame and smoke, fire dampers fitted where ducts serve two or more floors or pass through walls, and air intakes placed away from inflammable vapours or dust.
Exhaust fans help a room perform well, but they are not a substitute for the openings or air wells your approved plan needs. Ask your architect how your design meets these rules.
Step-by-step process
- Survey. The contractor checks each space, existing openings and where ducts can exit.
- Sizing. Fan size and duct size chosen for the room volume and use.
- Route planning. Shortest practical duct path with few bends, ending outside away from windows and neighbours.
- Proposal. Itemised list of fans, hoods, duct lengths, outlets and electrical points.
- Civil work. Openings cut in walls or slabs, with structural advice for large openings.
- Installation. Fans and ducts fixed, joints sealed, outlets fitted with back-draft flaps or cowls.
- Electrical. Switches, timers or sensors wired.
- Testing. Airflow checked at each point, noise checked, back-draft tested.
What affects the cost
We do not list prices; get written quotes. Cost depends on:
- Number and size of fans or hoods
- Duct length, size and material
- Wall or slab openings and making good
- Height and access
- Grease filters and fire-rated parts for commercial kitchens
- Controls such as timers or humidity sensors
- Noise reduction (lined ducts, silencers)
Questions to ask the contractor
- What fan size do you recommend for this room, and why?
- Where will the duct end, and will it blow towards a neighbour or window?
- Will there be a back-draft flap to stop dust and insects?
- How noisy will it be?
- For a commercial kitchen: how is grease handled and cleaned, and is fire protection considered?
Red flags
- A fan fixed into a wall with no thought to where the air goes.
- Long flexible ducts with many bends, which choke airflow.
- Kitchen exhaust ducted into a ceiling void instead of outside.
- No access for cleaning grease ducts in a restaurant.
- Large slab openings cut without asking a structural engineer.
FAQs
Is an exhaust fan enough for an internal toilet? It improves ventilation, but your approved plan must still meet LDA ventilation requirements, such as openings or air wells. Ask your architect.
How do I ventilate a basement? Basements usually need mechanical supply and exhaust. A contractor will size fans for the volume and use, such as parking or living space.
Can kitchen exhaust share a duct with toilet exhaust? It is generally better to keep them separate to avoid smells and grease travelling. Ask your HVAC designer.
Why does my exhaust fan let in dust? It may lack a back-draft shutter or cowl. These can usually be added.