If you manage a sealant package or sign off product submittals, you will see BS EN 15651 on data sheets and in specifications. It is the European standard for sealants used in non-structural joints in buildings and pedestrian walkways. It sounds technical, but the basic idea is simple. Each part covers a different end use, and a product is tested and classified for the uses it suits. This guide explains the structure in plain English.
The four parts
- Part 1: facade elements. Sealants for joints in external walls and facades, including movement joints between panels and around openings.
- Part 2: glazing. Sealants for glazing joints, where the sealant is in contact with glass.
- Part 3: sanitary joints. Sealants for washrooms, kitchens and other wet areas, where resistance to mould matters.
- Part 4: pedestrian walkways. Sealants for joints in floors and walkways that people walk on.
The standard covers non-structural joints. It is not about structural glazing, where the sealant holds glass in place.
Why the part matters
A sealant classified for one part has not necessarily been assessed for another. A facade sealant is not automatically suitable for a shower tray, and a sanitary silicone is not designed for a floor joint that takes trolleys. When you review a product, check that the data sheet or declaration of performance names the part that matches the joint. Some products are classified under more than one part.
Reading a product’s classification
Data sheets usually show which part a product meets, the type of use within that part (for example internal or external), and a movement class. Movement capability is the amount a sealant can stretch and compress as a proportion of the joint width while still performing. BS EN ISO 11600 also classifies building sealants by movement capability, and you may see both referenced. If the codes on a data sheet are unclear, ask the manufacturer or your sealant contractor to explain them in writing. Don’t guess.
Need the work done? Mastic Doctor covers South East England, London and all of Scotland, with a 12-month guarantee on our workmanship. Send details for a fixed quote.
How it fits with BS 6213
BS EN 15651 tells you how a product has been classified. BS 6213 is a guide to selecting construction sealants. It helps designers think about joint movement, exposure, substrates and service life before choosing a product. Many specifications cite both. Our sealant specification guide covers selection, and our joint design article covers the shape of the joint itself.
What it does not tell you
A good classification does not make a good joint on its own. The standard says nothing about whether the joint on your site is the right width, whether the faces were clean and dry, or whether a backing rod was used. It also does not cover fire performance. Fire-rated sealants are tested to separate fire standards, such as BS EN 1366-4 for linear joints, and classified under BS EN 13501-2 (see fire-rated vs intumescent sealant).
Practical checks for submittals
- Match each joint type on the drawings to a product and its BS EN 15651 part.
- Check the movement class suits the joint design.
- Check substrate compatibility and primer needs on the data sheet.
- Confirm colour options for the specified product.
- Keep data sheets with the O&M information for future maintenance.
Quick answers
Is BS EN 15651 a legal requirement?
It is a product standard, not a law in itself. Specifications often call for it, and manufacturers use it to declare performance. Follow what the project specification requires.
Does Part 3 mean a sealant won’t go mouldy?
No. Part 3 covers sealants for sanitary joints, including resistance to mould growth under test. In use, cleaning, ventilation and workmanship still decide how a joint looks over time.
Which part covers floor joints in a warehouse?
Part 4 covers pedestrian walkways. Joints that take forklifts and pallet trucks are a different case, and a semi-rigid filler or a trafficable sealant is chosen for the traffic and movement.
Where do I find a product’s classification?
On the manufacturer’s data sheet and declaration of performance. If either is missing or unclear, ask for it before the product is approved, and keep a copy with the project records.
Related services
- Construction and new-build mastic
- Commercial sealant contractors
- Commercial washroom and wet-area sealing
More advice
- Sealant Specification Guide for Contractors
- Silicone, Polyurethane or MS Polymer Sealant?
- Sealant Joint Design: Width, Depth and Backing
- Sealant Snagging Before Handover
- All advice
This guide is general information about sealant work. It isn’t legal, fire-safety or structural advice; for those, speak to a qualified professional.