Door Articles

The Complete Guide To Steel Doors


What’s in the guide?

  1. Introduction
  2. What are Steel Doors?
  3. Components
  4. Typical layout diagram
  5. What are the benefits of installing Steel Door?s
  6. Specifications
  7. Maintenance
  8. Safety Standards for Steel Doors
  9. FAQs
  10. Why choose HAG Ltd Steel Doors?
  11. Services offered by HAG Ltd.
  12. HAG Steel Doors product ranges


1. Introduction

HAG Ltd. have been providing quality bespoke Steel Doors, manufactured to suit specific site requirements, to companies in the UK and across the world for over 30 years. We know it can be difficult to find all the information necessary to choose the right doors for your premises, so we’ve put together this Complete Guide to Steel Doors to help make the process easier.


2. What are Steel Doors?

The installation of a HAG Steel Door product provides the ultimate in protection. Intruders will not be able to breach the Steel Door or framework with the same ease as a traditional Timber Door.

Locking devices and hardware incorporated in the HAG Steel Door system are also designed specifically to withstand such attacks and, with the additional benefits of fire protection, acoustic & thermal insulation make it the product of choice for today’s specifiers.

There does not need to be a compromise between style, security and energy efficiency for your property. As well as maintaining a robust exterior appearance, the range of Steel Doors available from HAG can provide everything the modern building requires, such as sound and heat-loss reduction.


3. Components

There are many components that make up the design of Steel Doors and work together to provide the best possible security, and keep your property safe from damage or ingress.

Door frame

The door frame is composed of extruded Galvanised Steel of at least 1.5mm thickness.

Door leaf

The door leaf is pressed from Galvanised Steel of at least 0.9mm thickness.


The type of infill depends on the specification of the door – for instance, thermal loss prevention would require a dense mineral wool, whilst Heightened Security Doors may have a solid hardwood core or a lattice-work of steel plates. Entry-level door sets always have an infill of dense cardboard in a honeycomb formation, this provides a good level of insulation and sound attenuation.


The finishing consists of polyester powder, which is applied to the external surface of the door. It gives the door a strong yet aesthetically attractive finish, which is typically applied to home appliances and office furniture. However, for those doors that are subjected to the worst that weather can offer (transformer stations, seafront environments etc.) then Marine Grade coatings can be employed.

4. The benefits of installing Steel Doors


Steel based structure in a steel frame.


Cheaper than aluminium or timber for equal security or fire resistance.

Sound and heat containment

Use of mineral wools can limit heat loss and noise transfer.

Modern Styling

The range of additional features in the market allows designers to combine aesthetic appeal with practicality.


5. Specifications

All of our steel doors, steel security doors, external steel doors and steel door sets are made bespoke to your project using high quality galvanised steel.

There are a number of variations to the standard HAG Steel Door that will benefit site-specific conditions, including the type of locking, door hardware, colour, vision panels and louvred ventilation.

When specifying a steel door for a project it’s important to consider the following:


6. Maintenance

It is important to make sure your doors are regularly serviced. Here are some of the checks that should be made regularly to ensure the safe operation of your Steel Door and prolong the life of the product.


Check all hinges for loose attaching screws, hinge pin wear or other notable defects. The door should always swing freely and smoothly without obstruction from the opened to latched (when latching device is used) position.

Lock sets, panic devices, fire exit hardware

Check all lock sets for loose attaching screws, latch wear or other notable defects. The door should always latch freely and smoothly without obstruction.

Strike plate

The strike plate should be firmly attached to the frame or inactive leaf of a pair of doors.

Closing devices

Check all closing devices for loose attaching screws, linkage arm and pin wear, fluid leakage or other notable defects.

Flush bolts

Check all flush bolts for loose attaching screws, rod bolt adjustment and strike plate (on both door and frame if so equipped) attachment.

Glass lights

The glazing material should be checked for cracks and/or missing pieces of glazing.

Door and frame finish

A general visual inspection of the door and frame finish should be periodically conducted.

Unobstructed operation

Fire rated and/or smoke control assemblies are specified and installed to meet “safety to life code requirements.”


A visual and operational inspection is periodically necessary for gaskets & weather strips such as perimeter and threshold seals.


7. Safety Standards for Steel Doors

Security of the HAG Steel Door range is compliant with BS EN 1627:2011 (the standard for burglar resistance of pedestrian door sets, windows, curtain walling, grilles and shutters) and/or PAS 24 (the standard for enhanced security performance requirements for door assemblies)


8. FAQs 

Why choose Steel Doors over aluminium?

Steel doors are stronger than their aluminium counterpart, compatible with fire wall requirements and are traditionally more economical.

What is the industry requirement for water resistance for Steel Doors?

Conventionally, doors are not manufactured to be watertight. Installation of seals and thresholds are required to ensure water resistance in normal environments.

For extreme applications, specialized watertight/airtight Door systems are available.

*Additional information regarding water resistance may be found in SDI 127H.

How do I select the right type of steel for Steel Doors and frames?

Electro-Galvanised Steel, or Zintec, is the industry norm with Stainless Steel Grades 316 or 304 available for those conditions that require the extra weather resistance properties they provide.

Galvanized Steel is grade S275 Mild Steel Sheet that has been galvanised through a process called Electrolysis. This is applied at point of manufacture and is therefore part of the structural make-up of the material, as opposed to a post manufacturing additive, such as Hot-Dip Galvanising.

When external prime paint is applied, Galvanized Steel provides high quality resistance to corrosion and rusting. SDI (Steel Door Institute) recommends use of the A Series specification of A40 or A60 for primer adhesion. The A60 specification is considered better than the A40 specification with respect to rust protection. However, SDI does not advocate the use of G-series due to its lower quality primer adhesion attributes.

What is the industry requirement for clearance around a Steel Door in a steel frame?

Where doors have been fire-rated, such clearances are subject to regulation under NFPA 80, “Fire Doors & Other Opening Protectives”. The clearance between the door and frame must occupy a space of at most 1/8″. Clearances between the adjacent edges of two doors must be 3/16″. Clearance from the lowest point of the door to the lowest point of the frame must not exceed 3/4″. Clearance between the door face and the stop must be 1/16″. SDI 100 A250.8-2.1.8 details more information on clearance.

What affects the cost of the door?

Among the factors that make up the cost of the door is the location. This informs the material quality and finish and security level, which in turn drives the specification of Ironmongery and Hardware.


9. Why choose HAG Ltd Steel Doors?

With a wide range of doors available, businesses and homeowners are assured to find the appropriate door system for their premises. Our experience since 1983 in manufacturing, design, installation and maintenance helps us to produce Steel Doors suited to your exact needs and requirements.

Custom Manufacturing

HAG Ltd have been manufacturing roller shutter for over 30 years.

Quality Materials

Constructed from steel with quality finishes, HAG Ltd uses the best materials for optimum protection, sleek aesthetic and durable products.

Wide Range of Solutions

Select from a wide range of products including general purpose Steel Doors, Fire Exit Doors, Fire Rated Steel Doors, High Security Steel Doors, Louvred Steel Doors, Communal Entrance Doors, Blast Resistant Doors, Acoustic Steel Doors and Internal Steel Doors.


Available with a variety of features and operations and can be specified and designed subject to client’s requirements.


10. Services offered by HAG Ltd.


Benefit from experience and knowledge with our Door System Design service. HAG can help you meet your specification requirements by designing a door system tailored to your existing premises or building design.


HAG provide an unequaled quality service during the installation process, with in-house qualified engineers equipped with industry relevant training and experience. Full contractual compliances are adhered to, with all engineers trained in all aspects of site process and management.

Maintenance and Repair Service

HAG operate 24/7, 365 days a year. We provide a skilled service and repair engineers who are qualified to NVQ level 2 to provide responsive and effective solutions.

HAG offer 12-month warranty on all new products, which means your products are guaranteed to work with efficiency and ease. At the end of the 12 month, you will be given the option to extend your warranty service for your chosen time span.

Powder Coating

High quality powder coating creates a professional finish to HAG products. A durable, fade resistant, long lasting finish applied by an award winning company. HAG powder coating provides an unparalleled finish for aluminium and steel products.


11. HAG Steel Door product ranges

We focus on the manufacture, assembly and installation of the highest quality range of steel security doors to offer the best choice for our customers.

Armourdoor General Purpose Steel Door AD05 

Armourdoor Fire Exit Steel Door AD10 

Fireguard Steel Door FD01

Armourdoor High Security Steel Door AD20

Armourdoor Louvred Steel Door AD30

Armourdoor Steel Communal Entrance Door AD40

Armourdoor Blast Resistant Door AD50

Armourdoor Acoustic Soundproof Steel Door AD60

Armourdoor Internal Steel Door AD70


Click here to view our full range of Steel Doors.



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