Safety, certificates and compliance, 29 October 2026
Wind uplift and fixings for roofing and cladding
Wind uplift is the suction that tries to lift a roof covering off. BS 5534 requires every single-lap tile and every ridge and hip tile to be mechanically fixed, with fixings set by a calculation based on BS EN 1991-1-4 and the site. You rarely do the sums yourself: tile and fastener manufacturers produce a free fixing specification from your site details.
What is wind uplift on a roof?
When wind passes over a roof it creates suction on parts of the surface. Marley's technical guidance says the leeward slope is always under suction, there's an area near the ridge where suction develops, and on roofs pitched below 30° the windward slope can see severe suction too. Above 35° the windward face generally sees positive pressure.
The problem is that suction can be greater than the weight of the tile. Marley puts it plainly: the uplift pressure caused by suction may be more than the dead weight of the tiles or slates, which is why they must be mechanically fixed.
What suction pressure means in lift per square metre
Wind pressure is given in pascals (Pa), newtons per square metre. Divide by 9.81 to see the mass it would lift off each square metre.
| 500 Pa of suction500 ÷ 9.81 | 51 kg per m² |
| 1,000 Pa (1 kPa) of suction1,000 ÷ 9.81 | 102 kg per m² |
| 1,500 Pa of suction1,500 ÷ 9.81 | 153 kg per m² |
| 2,000 Pa of suction2,000 ÷ 9.81 | 204 kg per m² |
What does BS 5534 require for fixings?
BS 5534 is the code of practice for slating and tiling. The current version is BS 5534:2014+A2:2018. Its 2015 changes, still in force, did three things that matter on every job:
- Assumed higher wind loads, which means more fixings generally.
- Required all single-lap tiles to be mechanically fixed, with perimeter tiles fixed at least twice.
- Stopped mortar being relied on as the only fixing. Ridge and hip tiles must be mechanically fixed regardless of mortar.
For double-lap plain tiles, Marley's guidance gives the minimum under BS 5534 as every tile in every fifth course twice mechanically fixed. Higher exposure needs more. Dry-fix ridge, hip and verge systems should meet BS 8612. LABC Warranty's summary notes one exception: small ridge and hip tiles on low details, no higher than 3 m, may be mortar-bedded if their own weight resists the wind load.
The 2018 amendment added a test-based wind uplift classification for underlays and limited underlay drape to about 15 mm, so the underlay doesn't balloon and pass wind load to the tiles. LABC says the UK is split into five underlay wind uplift zones, with the south east of England in zones 1 to 2. Check the underlay's label against your zone and batten gauge.
How is the wind uplift calculation done?
BS 5534 includes wind uplift formulas and a method for calculating fixing specifications. The site's basic wind speed comes from BS EN 1991-1-4 (Eurocode 1) and its UK National Annex. Factors for terrain, topography, building height and length are applied to that speed to get an effective wind speed and a dynamic pressure on the roof. Pressure coefficients for each part of the roof then give the suction, and the fixing needed to resist it.
Marley's own list of what a fixing specification weighs up: average wind speeds and loads, how exposed the roof is, the pitch, the height of the roof, and the weight and leading edge of the product. Marley's plain tile instructions say a full calculation is needed for its zone 3 and for sites above 300 m altitude.
Who should do the calculation?
For tiles and slates, the manufacturer. Most UK tile makers offer free tools or a technical service. BMI's FixMaster service, for example, asks for site details, roof dimensions, construction and features, and says the detailed specification is free, with a materials list expected within three working days. Marley offers online tools and a technical advisory service.
For profiled metal roofing and cladding, the calculation also follows BS EN 1991-1-4 with the UK National Annex. It sets the sheet capacity, the fastener pull-out and pull-over strengths, and how many fasteners go where. The Metal Cladding and Roofing Manufacturers Association's guidance document GD41 sets out the protocol, and fastener makers such as SFS run wind load calculation services. On commercial work the designer or the system supplier normally owns this calculation; your job is to get it in writing and install to it.
Subject: Fixing specification request: site address / job ref Hello, Please could you provide a BS 5534 fixing specification for the roof below. Site postcode: postcode Site altitude: metres above sea level Terrain: town / country / coastal Topography: flat / hill crest / escarpment / valley Building: house / bungalow / other, height to ridge m, length m Roof: pitch degrees, max rafter length m, rafter centres mm Covering: make, model, colour Underlay: product Well-sealed ceiling: yes / no Battens: size Counter-battens: size or none Details: ridge type, hips, verges, valleys, abutments, roof windows, solar Please include the nail and clip requirements by roof zone, and the ridge, hip and verge fixing method. Thanks, name company phone
Keep the specification with the job file and hand a copy over with the guarantee paperwork.
How does this affect your price?
More fixings cost more time and more clips. If you price from a rule of thumb and the specification comes back with every tile clipped at the perimeter and extra fixings near the ridge, the difference comes out of your margin. Get the specification before you quote, not after you win. Our guide to how to price a job covers the other costs that get missed.
Checking the specification against what's being ordered matters as much as getting it. A roofing and cladding firm in Ireland with eight workers told us a check during their Nexley trial flagged a non-compliant adhesive on XPS board and corrected the board coverage figure from 0.75 to 1.44 m² per board. The same kind of slip on clip counts means a roof that doesn't match its specification.
Fixings also belong in your safety paperwork. Your method statement should say how clips and fixings are handled at height, and HSE's roof work guidance on edge protection and fragile roofs applies to every job. The RAMS master template guide shows how to keep the roofing sections reusable, and health and safety for small firms covers the legal minimum.
Building regulations for structure differ between England, Wales, Scotland and Northern Ireland, but BS 5534 and the Eurocode wind method are used across the UK. For an unusual building, an exposed site or any doubt, get a structural engineer or the manufacturer's technical team to sign the specification off.
Where Nexley fits
Nexley is the AI back office for UK trade firms: five AI assistants run your tenders, quotes, buying, scheduling and invoicing. It connects to the tools you already work in, you run it all from WhatsApp, and you approve everything. £799 a month.
For roofing jobs, Nexley drafts the fixing specification request from your survey notes, chases the manufacturer for it, and checks the clip and nail counts on your materials order against it. You send the survey details as a voice note on WhatsApp and approve the request and the order before anything goes out.
Common questions
Do all roof tiles need to be clipped?
All single-lap tiles must be mechanically fixed under BS 5534, which means a nail, a clip, or both, as the fixing specification says. Plain tiles need at least every tile in every fifth course twice fixed, and more at the perimeter and in exposed areas.
Can I still bed ridge tiles in mortar?
You can use mortar, but it can't be the only fixing. Ridge and hip tiles must be mechanically fixed to resist the calculated uplift. Small ridge and hip tiles on low details up to 3 m may be an exception if their weight resists the wind load.
Is a fixing specification free?
From most tile manufacturers, yes. BMI says its FixMaster specification is free of charge. Check your manufacturer's own technical service.
Does wind uplift apply to underlays?
Yes. Since the 2018 amendment, underlays are classified for wind uplift resistance by test, and labelled for where and with which batten gauges they can be used. Drape should be limited to about 15 mm.
Sources
- Marley: Weather resistance, wind
- Marley: What are the fixing requirements of BS 5534?
- Marley: Changes to BS 5534
- Marley: How can I fix my tiles?
- Marley: Plain tile fitting instructions
- LABC Warranty: Roof tiling and underlays, the new BS 5534 standards
- LABC: Changes to underlay requirements in BS 5534
- BMI: Pitched roof fixing specification
- RCI: Understanding wind loadings and getting the calculations right
- SFS: Wind load calculations
- HSE: Roof work
Every rule, rate and date above was checked against these sources on the date shown at the top.
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