If your balcony or balustrade is going onto a plot covered by a structural warranty, the warranty provider's engineer will want more than a brochure. On an NHBC site the balcony conditions sit under Chapter 7.1 of the NHBC Standards, and they are not discharged until an engineer has seen the design, the connection into the building, and evidence of how it was actually installed. The same pattern applies to LABC Warranty, Premier Guarantee and the other providers, even where the paperwork is named differently. This page sets out what gets asked for, which parts of it we can supply, and which parts sit with your engineer or your builder. It is written from conditions we have cleared on live warranty sites, not from a template.
What the engineer actually asks for
The request is usually a single condition covering the balcony as a whole, broken into parts. The parts that touch the metalwork tend to be these.
- Structural calculations and drawings showing the connection to the primary structure
- Anchor size and type, and the material specification of the steel
- Resin or fixing details, with the manufacturer's data for the product used
- Calculations covering both the anchors and the steel members
- Thermal isolation at the point where the steel meets the building
- Resistance to vibration and movement under load
- Evidence that the infill, glass or otherwise, is adequate for infill loading
- An installation report with photographs showing what was actually built
Two of those are worth understanding properly before you order anything, because they are where submissions stall.
Fixing into masonry is where it usually stops
A generic technical data sheet for a resin will not clear a condition. Engineers ask for a site specific fixing design: the bolt, the embedment depth, the edge distance, the spacing, and the same again for the parapet as for the wall, because they are different conditions.
The question that comes up most often is what happens when a fixing lands in a mortar joint rather than the middle of a brick. On a parapet with coursed brickwork you cannot always choose. The answer is that an injection resin anchor behaves differently from an expansion anchor. An expansion anchor works by pushing outwards, which is what cracks a brick edge or blows out a joint. An injection resin bonds chemically along the length of the stud and distributes tension and shear into the surrounding masonry and the jointing as one mass, with no expansion stress. Where the masonry is perforated or hollow, a mesh sleeve keeps the resin where it is meant to be instead of letting it disappear into the voids.
That is the explanation that satisfies an engineer. It is also the reason we will not publish a standard fixing schedule. On one recent warranty site the fixing specification changed between the first submission and the final one as the design was worked through. A number taken off a web page is not a design.
Cold bridging where the steel meets the building
A steel wall plate bolted to a masonry facade is a path for heat to escape, and warranty providers ask about it. Our answer on warranty work is to encapsulate the wall plates in a nylon base coating before the topcoat goes on. That gives a thermal break between the primary steelwork and the masonry rather than steel sitting hard against the wall.
It is worth saying that this is a coating decision taken at the point of manufacture. It cannot be added afterwards, so it needs to be on the order rather than raised once the steel is on site.
Vibration and stiffness
Guarding that moves under hand load is a serviceability problem as well as a comfort one, and it is a question that gets asked. A chemically anchored connection combined with a coated interface gives a stiff joint, which is what stops the rattle and the perceptible movement you get from a bolted plate that relies on friction alone.
What we can supply
For steelwork we have manufactured, the following can be supplied. Some of it comes with the job and some of it is a chargeable piece of work, so it is worth asking at enquiry stage rather than assuming.
Available at no charge:
- Our UKCA certificate to BS EN 1090-2 and a Declaration of Performance
- The material specification, including the galvanising standard and the coating build up
- The manufacturer's technical data for the anchor and resin system specified
- General guidance on what a warranty engineer is likely to ask for
Available as a chargeable item:
- Project specific structural calculations for your arrangement and your loadings
- A site specific fixing design, as opposed to generic product data
- Drawings prepared for submission rather than for fabrication
- On site pull testing of anchors, where a provider asks for it
- A site visit to assess what the balustrade is fixing to
Read our UKCA certification page for what the marking covers and, just as importantly, what it does not. Note in particular that it applies to steelwork we fabricate, not to proprietary components bought in as part of a frameless system.
What sits with you and your engineer
We are a fabricator. We are not a warranty provider, a building control body, or the engineer of record for your building, and we cannot discharge a condition on your behalf. The site specific design of a fixing into your particular wall depends on the substrate, and nobody can confirm that from a photograph.
What we will do is help. General advice costs nothing and we will give you as much of it as is useful, including talking to your engineer or your warranty inspector directly if that moves things along. It often does. Where the request becomes a piece of design work in its own right, calculations for your specific arrangement, a fixing design for your wall, or testing on site, that is chargeable and we will tell you so before we start it.
In practice the submissions that clear quickly are the ones where the information goes to the warranty engineer directly rather than through three parties, and where the fixing design is settled before installation rather than evidenced afterwards.
What to send us
If you are quoting a plot that carries a warranty, tell us at enquiry stage rather than after the order. Send the condition wording itself, the drawings, and a photograph of what the balustrade is fixing to. That lets us price the right coating specification from the start, and lets us tell you early what is included and what will be chargeable.
Send it to sales@diomet.co.uk or see how to get a price from us.
The technical bit
Our structural steelwork is UKCA marked to BS EN 1090-2 and manufactured under documented factory production control by coded welders. Guarding is designed to BS 6180 and Approved Document K, with barrier loadings taken at 0.74 kN/m for single family dwellings and higher where the use demands it. Steel for external warranty work is hot dip galvanised to BS EN ISO 1461 before coating. Stainless fixings are specified by grade for the exposure, with A4 used externally. Required glass thickness varies with size, support condition and use, and where there is doubt that is a question for a structural glass engineer. Meeting the requirements of your own warranty provider and building control remains your responsibility.