Louver Doors and Shaft Doors in Bangladesh: When to Use SFD 504 and SFD 505

Two special doors, two different jobs

Most fire doors in a building are ordinary single or double leaf doors on corridors and stairs. Two other door types solve specific problems and are often confused with each other.

Both belong to the Safety Plus fire door range, which the catalogue describes with 1.2 mm steel skins and a 50 mm door thickness, in cold-rolled mild steel or galvanised steel. Their purpose and their fire performance questions are quite different, so they are treated separately below. For standard single and double leaf doors, see the fire door sizes guide.

Louver doors (SFD 504): when a room needs to breathe

Many plant rooms need a constant supply of air. A diesel generator needs combustion and cooling air. Transformers and switchboards shed heat. Battery rooms need ventilation. Pump rooms get damp without airflow. Store rooms holding cartons or yarn in Bangladesh's humid climate may need air movement to limit mould and condensation.

A louver door provides that airflow through angled blades set into the leaf, while still giving a lockable, robust steel door. Good louver door design considers:

• Free area: the open area of the louvre, which decides how much air can pass. Your mechanical engineer should set the required free area from the equipment's air demand.
• Blade profile: angled blades shed rain on external doors and block direct sight into the room.
• Insect and bird mesh behind the blades, especially for ground-floor and external doors.
• Position of louvres: low louvres admit cool air, high louvres release hot air; some rooms need both.
• Security: blades fixed so they cannot be removed from outside.

For larger airflows through walls rather than doors, separate industrial louvers are usually the better solution.

The trade-off: ventilation vs fire separation

This is the most important point in this guide. A louvre is an opening. An opening lets smoke and flame through. A generator room or electrical room is often exactly the kind of room that a fire safety plan requires to be separated from the rest of the building by fire-rated walls and doors. Putting an ordinary louvered door in that wall can undo the separation.

There are three ways to handle it:

If you need a louver door in a fire-rated wall, ask the supplier directly: what fire rating, if any, does this louvered configuration have, and which test report proves it? If the answer is unclear, choose the second approach. Your fire safety consultant should make this decision, not the door supplier alone.

Shaft doors (SFD 505): protecting vertical service routes

Service shafts, also called risers, run vertically through a building carrying electrical cables, bus ducts, plumbing, fire water pipes, telecom cables or ventilation ducts. Because they connect every floor, an unprotected shaft can carry smoke and fire from one storey to the next very quickly. For that reason shafts are normally enclosed by fire-rated walls, and the access doors on each floor are a weak point if they are not equally protected.

A shaft door gives maintenance staff access while keeping the enclosure closed. Points to consider:

• Rating should match the shaft enclosure as set by your consultant; a shaft wall and its door work as one system.
• Size depends on what must be installed or replaced through it: cable drums, bus duct sections, valves or pumps. Shaft doors can be smaller than corridor doors, or full height where equipment demands it.
• Locking: shaft doors are for authorised staff only, so they are usually kept closed and locked rather than used as through-doors.
• Fire-stopping at each floor slab inside the shaft is a separate but essential measure; a good door on a shaft with open slab penetrations offers little protection.
• Corrosion: plumbing shafts can be damp, so pretreatment and paint quality matter. See powder coated steel fabrication.

Choosing the right door by room

For factories and plant-heavy facilities, see the power and industrial plants page.

What to specify for louver and shaft doors

Add these lines to your tender or purchase request:

1. Door type and model: louver door (SFD 504) or shaft door (SFD 505).
2. Location and wall rating of each door.
3. Required fire rating, or a clear statement that no rating is required.
4. For louver doors: required free area, louvre position (high, low, both), mesh, external or internal use.
5. For shaft doors: clear opening needed for equipment, height above floor, locking arrangement.
6. Material and finish: cold-rolled mild steel or galvanised steel, or stainless steel for corrosive areas; RAL colour.
7. Test evidence that supports any claimed rating for the exact configuration.
8. Labels and signage, such as "Electrical shaft — authorised personnel only".

You can send these requirements to Safety Plus through the request a quote page, and see the complete door range on the fire rated doors page.

Maintenance notes

Louver doors need cleaning. In textile and garment factories, lint and dust collect on louvre blades and mesh, cutting airflow and adding fuel near hot equipment. Include louvre cleaning in the monthly maintenance round, and check blades are not bent, removed or blocked with cartons.

Shaft doors are opened rarely, which is a risk of its own: locks seize, hinges corrode and doors get left unlocked after maintenance. Check that each shaft door is closed and locked during routine rounds, and inspect hinges, frame and labels during the annual fire door inspection described in the fire door inspection checklist.

Frequently asked questions