The Warmup Expansion Strip is designed for use around the perimeter of screeded floors, helping to accommodate natural movement as the screed expands and contracts. Suitable for both heated and unheated screed floors, the compressible strip creates a separation between the screed and surrounding walls or other fixed elements, helping to reduce the risk of structural damage caused by movement.
The expansion strip is particularly important when installing underfloor heating within a screed floor, where temperature changes can cause the floor structure to expand and contract during operation.
Screed naturally expands and contracts as it cures and subsequently responds to seasonal and temperature changes. When underfloor heating is installed, additional thermal movement can occur as the system heats and cools.
The Warmup Expansion Strip provides a compressible separation between the screed and surrounding walls, allowing the floor to move without being constrained by adjacent structures. Warmup recommends using a 10mm thick compressible perimeter strip around screeded rooms and around penetrations such as pipes passing through the screed.
The expansion strip forms part of the floor construction when installing Warmup hydronic underfloor heating systems within screed. It is particularly relevant to systems such as the Warmup Forte Grid System, where the pipework is incorporated within concrete or structural screed floors.
Warmup's Forte system details specifically show the perimeter expansion strip positioned between the screed and surrounding walls.
A heated screed can experience expansion and contraction during normal operation. Providing a compressible perimeter allows the floor to accommodate this movement rather than transferring stress directly into surrounding walls or fixed structures.
The expansion strip also provides a degree of thermal separation between the heated floor and the wall, helping to minimise thermal bridging at the perimeter.
Warmup's technical guidance specifies a 10mm thick compressible perimeter strip for separating screed from walls and accommodating floor movement.
The Warmup Expansion Strip should be installed continuously around the perimeter of the room before the screed is laid, creating a separation between the screed and surrounding walls.
It can also be used around suitable penetrations through the screed, such as pipes rising through the floor. The strip should remain in position during screeding to maintain the required movement allowance.
For underfloor heating installations, follow the installation requirements for the specific Warmup system and screed construction being used.
Perimeter expansion strip and expansion joints serve different purposes. The perimeter strip separates the screed from surrounding walls, while additional expansion joints may be required within larger heated screed areas.
Warmup's technical guidance states that, in accordance with BS EN 1264-4, expansion joints should be used for every 40m², with a maximum length of 8m and an aspect ratio of 2:1. Where underfloor heating pipe crosses an expansion joint, the pipe should be enclosed within conduit extending at least 300mm on either side of the joint.
The Warmup Expansion Strip is suitable for:
The expansion strip is a floor construction accessory and is not a heating element.
Correct provision for floor movement is an important part of screed construction. Always follow the relevant Warmup installation instructions, screed manufacturer's requirements and applicable British Standards when designing and installing an underfloor heating system.
Where internal expansion joints are required, these should be designed and installed separately from the perimeter expansion strip.
The Warmup Expansion Strip provides a straightforward solution for separating screed floors from surrounding walls and allowing for natural floor movement. Its compressible 10mm profile makes it suitable for both heated and unheated screed constructions, including Warmup underfloor heating systems.

Warmup Expansion Strip
25m