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Frequently asked questions

Whatever questions you might have about our range of products and services, we’re here to help. Here’s some of our most frequently asked questions.

How can we help you?

If you can’t find the answer you are looking for here, please do get in touch.

Why is PVC edge protection better than aluminium? Aluminium edge protectors are renowned for leaving sharp edges or even protruding metal fragments in the event of an impact. PVC edge protectors do not do this, yet they offer an equal resistance to impact. PVC edge protectors are also available in any of our defend colour range, meaning that if a contrasting colour is required for building regs, this can be easily achieved. Further benefits include the ease of machining for locks and keeps compared to aluminium.
Who can install a fire door? Technically, anyone can install a fire door! Whilst there are many guidelines regarding fire door installation such as Building Regulations, the BM TRADA Q-Mark Fire Door Installation scheme, the British Standard Code of practice for fire door assemblies, and the BWF- CERTIFIRE Scheme, there is not actually a legal requirement for a fire door installer to be part of one of these schemes. However, it is a legal requirement for every public building to be suitably protected against the spread of fire, and many building control officers will ask for a certain level of competency to be demonstrated by a fire door installer before they accept the fire door installation. It is worth noting that an incorrectly installed fire door may provide very little, or even no protection against fire!
What are the maximum gaps allowed around a fire door? The maximum permitted tolerance between the door leaf and the door frame is 3-4mm around the sides and the head of a fire door assembly. The maximum tolerance between the bottom of the door leaf and the finished floor level is 10mm. However, if the doorset is required to provide protection against cold smoke, then the tolerance at the bottom of the leaf should be reduced to 3mm in accordance with BS EN 9999-2017, unless a dropseal is fitted to the bottom of the door.
What is anti-microbial ironmongery and how does it work? The SDS range of Define Ironmongery is treated with a coating containing silver ions, which actively destroys the cell membranes of any germs on the surface of the ironmongery, causing them to breakdown and die!
Explain LRV values?

LRV stands for Light Reflectance Value, which is a measure of how much visible light is reflected from a surface when illuminated by a light source. Further details and an LRV calculator can be found here.

Can you colour match any colour with your PVC?

SDS are able to colour match our defend PVC to any RAL or Pantone colour reference – subject to minimum lead times and order quantities.

Do you do a range of compatible ironmongery?

SDS offer a complete range of compatible ironmongery.  Further details as to this can be found here.

Do your doors have a manufacturer’s warranty? SDS is pleased to offer a 5 year warranty subject to standard terms of usage.
What is a Part M compliant vision panel? There is a minimum zone of visibility required for all glazed doors to ensure user safety. This is set out in the Building Regulations Approved Document Part M (BS8300) and the Equality Act (EA) 2010. SDS offer a number of standard vision panel designs which are part M compliant. Further details of these designs can be found here.
What is Effective Clear Width? The Building Regulations Approved Document Part M (BS 8300-2:2018), sets out minimum widths for doorways to ensure that all users (particularly wheelchair users) are able to gain unrestricted access. These minimum widths can be are known as ‘Effective Clear Widths’.  Further details, and an Effective Clear Widths calculator can be found here.
What is the impact that the door has on air quality in the hospital? We have no evidence to suggest that the doors have any impact on the air quality in a hospital.
Do we offer a Carbon Neutral Door? While we don’t offer a carbon neutral door, as a company, we are a Carbon Neutral, supporting various schemes such as community reforestation in Ghana.
Do we offer more colours than we show on our swatch?

Our full colour range can be found online by clicking here.

While we do offer a colour matching service, we typically don’t recommend this as there is a minimum order quantity which can makes smaller orders or maintenance a challenge.

What is the maximum width of door frame that our split frames can handle?


How does the Copper Nickel kill bacteria? The copper-nickel alloy features antibacterial properties which work 24/7, never washing out or wearing away, making it the ideal choice where infection control is paramount. Our Copper Nickel range of ironmongery is manufactured using a 70-30 copper-nickel alloy, which makes the range
tarnish-resistant and will not oxidize and patinate like pure copper.
What is the cost difference? As a comparison Dfendoor is typically 30% more expensive than a laminate door, Lamdoor is priced to be more competitive with the laminate prices.
What areas are suitable for Lamdoor and Dfendoor? Dfendoor is meant for high traffic hospital environments. Lamdoor can be used in busy, high wear education, retail, and hospitality environments.
How long does that data remain on the NFC chip? We have doors that have been there for 50 years The data on the NFC chips is designed to be ongoing, the data is kept on the NFC chips for ongoing compliance.


We are very proud of our 40-year track record of successful collaboration with architects, contractors, NHS Trusts and private hospitals, partnerships which are based on our core tenets: Specialisation, Dedication and Sincerity.


If you have any questions about any of our products or services, our friendly team of experts will be glad to help you.