Frequently Asked Questions

No, Strongdor are a supply only manufacturer and therefore unfortunately don't offer site surveys or installation. However we can recommend local installers in your area from our Doorfit Network, who will be happy to help.

Complete our quotation request form, mention you are looking for installation and we will put you in touch!

The clear opening width is the size of the gap any persons/objects can pass through freely when the door is opened to its full potential. View our full document on Clear Opening Width's.

Strongdor Ltd are specialists in the manufacture and supply of quality steel doors for commercial clients throughout the UK.

Strongdor Ltd are committed to promoting sustainability and continually working to reduce the environmental impacts of all aspects of our business.

You can read our full sustainability policy here.

In simple words, yes . All our doors are individually constructed using the same process, however the Firedor range does come with additional features that set them apart from our standard Steeldor sets.

No, these dimensions are not the same. The structural opening size refers to the internal measurements of your aperture. When requesting a quotation from us, it is crucial to specify only the structural opening size. For more information on how to accurately measure the structural opening, you can view our easy online guide within the Knowledge Library on our website.

The clear opening width is the size of the gap any persons objects can pass through freely when the door is opened to its full potential. Be aware that any hardware that protrudes into the door opening will be deducted from the clear opening width. You must ensure your door complies with building regulations by consulting your Building Regulations officer. While Strongdor does not carry qualifications to advise on building specifications – we can give guidance on whether our doors comply with a specified standard.

Stainless steel grade 13-8 is an age-hardened steel with excellent resistance to stress and general corrosion cracking, achieved through a single low-temperature heat treatment.

Different thresholds are required for both inward and outward opening doors. As standard, if not stated, the steel door experts will quote for a 96mm steel door threshold for outward opening external doors.

As standard all our door-sets come with a fixing kit. These are tailored to the aperture material you will be installing into and include steel, concrete, brick, and timber.

You can view all fixing kits in our image library here. 

Our frames are manufactured from 1.5 mm thick ‘Rustec’ steel with a minimum of six fully adjustable fixing points provided to each jamb. The unique ‘Adjust2-fit’ side channels allow 12mm expansion on each side of the frame to ensure the fit is seamless.

The interlocking seams, commonly referred to as Dutch folds, involve connecting the two skins through a folded crimp on each side, followed by stitch welding on both sides.

The gap between the threshold and the underside of the door leaf.

An astragal is a section on the leading edge of the door leaf that is used on a single and a pair of doors to cover and help seal the gap between the doors/ frame when they are closed.

Monarch EN1935 Grade 13 Butt Hinge Stainless Steel 102 x 75mm.

Locking bolts for the inactive door leaf on a double door set.

Our insulated core will take your door-sets down to a U-value as low as 1.5 for double doors and 1.6 for singles*. *Subject to size and options selected on the door.

This would be dependent on the location of your installation; however, our most popular accessories include letter boxes, door viewers, vision panels, louvres, rain drips & deflectors, trolley guards and rebound panels.

Yes, this is primarily for safety reasons. Our standard single-door sets typically weigh approximately 60kg for both the leaf and frame. Meanwhile, our SR2 single-door range boasts a weight of around 100kg for both the leaf and frame.

In the simplest terms, a test standard that is used to assess the security performance of windows and doors. PAS 24 certification confirms that a UKAS (United Kingdom Accreditation Service) accredited certification body has monitored the security performance of products under set test conditions. 

To manufacture the best fitting door, Strongdor will require the structural opening (brick to brick).

We will make the necessary fitting allowances on the size of the door frame. If the opening is wider at the top than the bottom or vice versa, please give us the width at the narrowest point.

View our knowledge library document - Accurately Measuring For Your Steel Door for further guidance.

It is the customer’s responsibility to ensure all details within the sales quotation / sales order meet the exact specification and / or original enquiry and are compliant with current building regulations including location and method of installation.

We are here to help and advise only and cannot accept responsibility for discrepancies after the order is confirmed.

Strongdor Terms and Conditions

For any door that is installed within 5km of the coast, we recommend that you talk to one of our sales team members about specialist door coatings.

Please ensure you advise our sales team when making your initial enquiry and they will quote accordingly.

Our aim is deliver all orders on time in full, but there will sometimes be delays for reasons outside of our control.

It is your responsibility to check the products on delivery before signing for the goods. Any claims for damaged goods after they have been delivered and signed for, are not covered.

Strongdor cannot accept liability for failed or delayed delivery and will always try and redeliver within a reasonable amount of time.

Refer to Strongdor Terms and Conditions and the Despatch Important Information Document. 

Previously in a single door-set your keys were cable tied to the door frame and in a double door-set your keys were in the fixing kit located in the door frame.

Strongdor has recently changed this, meaning that in both single and double door-sets your key will always be located in your fixing kit within a small plastic bag. 

We recommend using the services of a professional installer – or if you intend to install the doors yourself, we have helpful online Fitting Videos.

An Installation and Maintenance Instruction booklet will be included in your fixing kit and all additional Installation Guides are available on our website. 

If you have any questions we have a dedicated customer service team on hand to provide assistance – please call and ask to speak to the Customer Service Team.

Unfortunately there is no simple answer to this question as all security rated door-sets have protection enhancement. The level of security required for your door-set will be dependent on the location and specification of your installation.

Check out our documents LPS 1175 vs PAS 24:2016 and LPS 1175 Explained to see which security rating may be best for you!

This is quite a common issue and is due to the way we pack our doors. Expander side channels are packed down the side of the doors before we wrap the, making them appear too wide.

When you unpack your doors it will be clear that the channels are separate and need to be fitted to the door during installation.