Insulation under screed: Which materials really protect and provide lasting support

Insulation under screed is about more than just thermal insulation: compressive strength, moisture resistance and ecology make all the difference.

Structure, function and variants of screed insulation

Screed insulation is used to protect against cold, moisture and mechanical stress. There are two basic systems to choose from:

Insulating gravel under screed: Mineral products such as glass cellular gravel are ideal for uneven substrates or under floor slabs in new builds. They are capillary-breaking, pressure-resistant and open to diffusion.
Insulation boards under screed: EPS and XPS are widely used, but are at a clear disadvantage in terms of environmental compatibility, moisture protection and fire safety: they are flammable, based on crude oil and react sensitively to moisture. GLAPOR cellular glass boards, on the other hand, are non-combustible (A1), water-resistant, pressure-resistant up to 1,600 kPa and consist of 100% recycled glass – permanently stable and ecologically superior.

Which insulation under screed: cellular glass, XPS & EPS in comparison

Criterion	GLAPOR cellular glass boards	XPS
Raw material	✓ 100 % recycled glass	Petroleum based
Water absorption	✓ None (vapor-tight)	Possible through diffusion
Compressive strength	✓ Up to 1,600 kPa - also suitable for parking decks	Max. 700 kPa
Fire protection class	✓ A1 (non-combustible)	B1-B2 (flammable)
Emissions / leaching	✓ None - emission-free	Waste disperses during processing
Waste disposal	✓ Reusable, urban mining ready	Construction waste or hazardous waste
Lifespan	✓ Lifelong - across generations	Characteristics fluctuate with moistening

Innovation: Insulating the floor slab has never been so easy!

GLAPOR RDS combination perimeter system

Plastic-free, waterproof, pressure-resistant. cellular glass boards as certified formwork. Cellular glass gravel as load-bearing thermal insulation. In combination, the healthy basis for every house.

UMB1: Urban mining base plate

The world’s first 100% circular floor slab without concrete. Quickly laid – up to 100 m² per day. Insulates reliably, supports up to 160 t/m² and saves up to 95 % CO₂.

Not sure which product

is the right one for you?

GLAPOR Technology Team

+49 (0) 9633-400769-0
technik@glapor.de

Guaranteed free of charge & non-binding

Why cellular glass is the best choice for insulation under screed

Whether residential construction, renovation of old buildings or industrial areas – insulation under screed must do more than just insulate. What is required is a building material that is permanently resilient, moisture-resistant and sustainable – without compromising on safety or ecology.

High-pressure resistant & dimensionally stable: no subsidence, no deformation – even with point loads
Moisture-resistant & rot-proof: zero water absorption, no loss of insulation value
Non-combustible (A1): Highest fire safety in the floor structure
Free from plastics: Ideal for sustainable building according to EU taxonomy & DGNB

Whether as load-bearing cellular glass gravel under the floor slab or as a cellular glass slab under the screed – GLAPOR cellular glass meets all the requirements of modern floor structures. A solution with a system – and a future.