Expansion joint details and specification, for architects and consultants

Three things we do for specifiers, before anyone has bought anything

Movement joint details: the systems we make in India, in section

Product illustrations, not shop drawings — they show how each joint sits in the slab and where the movement is taken. Gap ranges and movement capacities are from the current Vexcolt Systems tables; the data sheet behind each drawing has the row-by-row figures. Every data sheet download is free and needs no sign-up.

MegAtec 300 — floor to floor

Gaps 25–250 mm · movement about a quarter of the gap · set on the structural slab

Male–female plate system for trafficked floors under tile, stone and screed finishes. The A02 corner variant turns the same joint up the wall.

Data sheet (PDF) →   Product page →

MegAtec 340 — floor, self-aligning

Gaps 25–300 mm · movement half the gap · centring bar keeps the plate centred

The floor system for wide gaps and heavy movement; its centring bar is what the “self-aligning” wording in the DSR floor-joint item describes.

Data sheet (PDF) →   Product page →

MegAtec 370 — floor, fitted from finish level

Gaps 25–150 mm · movement half the gap · 6 mm plate

For thin finishes and shallow rebates: the frame fixes from finished-floor level rather than the structural slab, so it suits fit-out and refurbishment.

Data sheet (PDF) →   Product page →

Wall system · A07 / A09

MegAtec 360 — wall, corner and ceiling

Gaps 25–200 mm · wall-to-wall movement half the gap; corner and ceiling a quarter

Flush wall and ceiling covers with no visible fixings. Size the corner and ceiling transitions from the A09 row, not the wall row — the same gap gives half the movement there.

Data sheet (PDF) →   Product page →

MegAtec 610 — roof and terrace

Gaps 25–300 mm · movement half the gap · external centre-plate system

The external joint for roofs, terraces and podium tops, where the daily thermal range is the widest in the building and the waterproofing lap has to be designed, not hoped for.

Data sheet (PDF) →   Product page →

SeismAtec 450 — seismic floor joint

Gaps 50–500 mm · thermal ±25 mm at every gap · seismic movement half the gap

Central pan system for the structural separation between independent blocks in Zones III, IV and V. Two movement columns on its table — read both.

Data sheet (PDF) →   Product page →

FlexAtec 1200 — seal joint

Gaps 25–75 mm · movement about three-tenths of the gap · ribbed surface

A compression seal for narrow gaps where a metal cover is not wanted — floors, walls and the wall-to-wall return. Made in India at 25 and 50 mm.

Data sheet (PDF) →   Product page →

Floor-to-wall corners — the A02 joints

Every floor system above has a corner variant from the same range

Where a floor joint meets a wall, the corner joint keeps the movement continuous instead of stopping at a sealant line. Schedule it as its own location; it has its own row in every table.

300 A02 data sheet →   370 A02 →

Also made in India: MegAtec 310 (metal floor and wall joint, gaps to 250 mm). A fire barrier is available on request, its rating confirmed per job; moisture barriers are supplied with the joint where the location needs them. Not sure which row you need? How to read a movement capacity table takes ten minutes.

Every section we make in India

All 15 drawings, A01 to A09, each with its data sheet and the CAD detail on request. Illustrations from the data sheets, not shop drawings.

A clause you can adapt

Writing to a CPWD tender? Items 5.44, 5.45 and 5.46 of the DSR cover floor, wall and roof joints. What each one asks for, and what the BOQ should add.

Worked for a trafficked internal floor joint at a 100 mm gap. Change the gap, the movement and the traffic to suit each location on the schedule; leave the structure alone. It names nine testable requirements and no manufacturer — which is exactly what stops it being substituted.

Supply and install a proprietary architectural movement joint system to the locations scheduled, for a nominal structural gap of 100 mm, accommodating a movement range of not less than ±25 mm together with vertical offset and lateral shear. The system shall be cyclically tested to ASTM E-1399 and the tested movement class shall be submitted. Cover to be flush with the adjacent finish, trafficable under wheeled point loads, and continuous through wall and ceiling returns using components from the same manufacturer’s range. A continuous waterproofing membrane shall be installed within the joint and bonded to the structural membrane both sides; the lap is within this subcontract. Manufacture shall be against a site survey of the built gap taken after the structure is complete. Technical data sheets and installation method statement to be submitted for approval before manufacture.

The nine things the clause has to name

• A location schedule, not a quantity
• The gap width, per location
• The movement — range and direction
• The movement class and the test standard behind it
• The load rating, matched to the actual traffic
• Waterproofing, and where it is required
• Fire, where the joint crosses a compartment line
• The finish and the sightline
• Who installs it, and against what survey

Each point is explained, with the three structural mistakes clauses usually make, in how to specify an expansion joint.

The numbers behind the schedule

For a joint schedule, we need five things

• GFC or tender plans with the movement-joint lines marked — PDF or DWG.
• The structural gap at each line, and whether it separates structurally independent blocks (the seismic case).
• Floor build-up and finish at each location — tile, stone, vinyl, carpet, screed depth.
• Traffic — pedestrian, trolley, pallet truck, forklift, vehicles.
• Exposure — internal, external, over occupied space, podium or basement, and any fire compartment lines the joint crosses.

Manufactured in India since 2012 under licence from Vexcolt Ltd, UK — hospitals, metro depots, railway stations, IT parks and malls across India. Supply and installation by our own teams, so the survey, the joint and the fixing are one responsibility.