How to read positive and negative movement values
Read movement values using the catalogue's stated reference position and units. Opening capacity and closing capacity are separate checks, not a single number to compare by appearance.

Selection considerations
If movement is expressed as a percentage, establish which nominal dimension the percentage refers to. If values are listed in millimetres, keep those units in the comparison sheet. Do not combine percentage and millimetre entries without a documented conversion basis.
The engineer's required range should be checked against the system's published range and installation condition. Ask how temperature or the measured site gap affects setting-out. Record any lateral or vertical movement requirement as another line rather than assuming it is included. This approach avoids selecting two similar sections that serve different movement envelopes.
Before you specify or order
- Confirm units and reference gap
- Compare opening and closing separately
- Record other movement directions
Relevant BULDX catalogue examples
These records illustrate the product types discussed. Compare the full specifications before selecting; listing here does not establish project suitability or make the items interchangeable.

BDX-EJ-FL-RF-100-45-310-P30-N60-AL · Product geometry from the catalogue; a family illustration may be shared by variants. Consult the selected technical documents for dimensions and the approved fixing detail.| Product and code | Selected catalogue fields |
|---|---|
BDX-EJ-FL-RF-100-45-310-P30-N60-ALRecessed Seismic Floor Joint · 100 mm opening · 45 mm heightSeismic Floor Joints |
|
BDX-EJ-UF-1-100100 mm Under-Floor Expansion Joint - Type 1Under-Floor Joints |
|
BDX-EJ-UF-2-100100 mm Under-Floor Expansion Joint - Type 2Under-Floor Joints |
|
Common question
Does a total movement figure describe every direction?
No. Confirm the directions and reference condition covered by the published figure.
References and scope
Product fields are from the BULDX catalogue. Confirm the current selected drawing, supporting performance documents and approved project detail before ordering. External references, where listed, provide background guidance and do not certify these products.