Renovating floors in old buildings

Renovating floors in old buildings means stopping heat loss, reducing impact sound and protecting the structure – with durable, moisture-resistant and ecological insulation materials such as cellular glass.

Step-by-step: How to successfully renovate the floor of an old building

Step-by-step instructions for ecological floor renovation in old buildings with cellular glass gravel

Dismantling: Remove old floor covering and insulation if necessary.
Prepare the substrate: Excavate the ground, but not deeper than the strip foundation.
Choose insulation: Ecological material with thermal and moisture protection, e.g. cellular glass gravel.
Insert insulation: Lay out geotextile, compact cellular glass in layers at a ratio of 1.3:1.
Leveling: Apply leveling fill or screed for a level floor.
Substructure & floor covering: Lay parquet, laminate or tiles.

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Renovating floors in old buildings: a comparison of materials

Criterion	GLAPOR cellular glass gravel	EPS / XPS / PUR	Mineral fiber insulation	Wood fiber	Perlite / expanded clay	Cork
Raw material base	✓ 100 % recycled glass	Petroleum-based	Sand & lime (mined)	Wood	Volcanic rock / clay	Bark / natural material
Water absorption	✓ None	Possible through diffusion	Possible	Sensitive to moisture	Capillary active	Limited moisture resistance
Compressive strength	✓ Up to 800 kPa	Max. 700 kPa	Rather low	Low	Only load-bearing with compaction	Low
Fire protection class	✓ A1 (non-combustible)	B1-B2 (flammable)	A1	B2 (treated)	A1	B2-B3
Emissions / leaching	✓ None - emission-free	Waste is distributed during processing	Fiber dust possible during installation	Not specified	Not specified	Not specified
Waste disposal	✓ Reusable, urban mining ready	Construction waste or hazardous waste	Cumbersome, partly requiring landfill (with bitumen lamination)	Good, but high energy requirement	Not reusable	Limited recyclability
Service life	✓ Lifelong - across generations	Characteristics fluctuate with moistening	Properties change with moisture	Sensitive to moisture - limited duration	Permanent when used correctly	Naturally limited shelf life

Products for floor insulation in old buildings

GLAPOR cellular glass gravel

Lightweight, pressure-resistant and capillary-breaking. Quick to install, permanently insulating and rot-proof – ideal for traffic areas, building foundations and structural lightweight construction.

GLAPOR geotextile

Tear-resistant, reliable, durable. The robust geotextile from GLAPOR – perfect for cellular glass gravel applications in the perimeter area.

Floor insulation in old buildings: cellular glass as a safe solution

When renovating old buildings – whether half-timbered, listed or existing – durable, pollutant-free insulation materials are required. GLAPOR cellular glass meets all the important requirements:

✔ Non-combustible (A1)
✔ Water-resistant: no mold, no rot
✔ Dimensionally stable & pressure-resistant
✔ Rodent & insect-resistant
✔ Free from harmful substances & fully recyclable

Cellular glass gravel is suitable as a load-bearing, capillary-breaking insulation layer.

cellular glass boards enable structures with compression-free properties for the interior. Both systems can be installed quickly, cleanly and without special tools.

Produced from 100% recycled glass, GLAPOR insulating materials make a measurable contribution to CO₂ reduction – without any hazardous waste or microplastics.

More information and details on floor construction with GLAPOR and mineralized wood chips from Cemwood in our brochure.

Renovating old building floors with ecological cellular glass gravel

Soil restoration with cellular glass gravel

Fussboden Aufbau Bodensanierung im Altbau mit Schaumglas

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✔ Customized project consulting

cellular glass 100% made in Germany

✔ 1 00+ million m³ of cellular glass installed

✔ Customized project consulting

cellular glass 100% made in Germany

✔ 100,000,000+ m³ of cellular glass installed

Frequently asked questions (FAQ) about floor renovation in old buildings

FAQ

How can you insulate the floor retrospectively?

Retrofitting insulation to a floor is possible in almost all old buildings. First, the old floor covering is removed. Depending on the structure (e.g. wooden beam ceiling, solid ceiling or floor slab), a suitable insulation layer is then installed.

Loose fill with GLAPOR cellular glass gravel has proven its worth for wooden beam ceilings: It is pressure-resistant, insensitive to moisture, free-flowing and can fill the cavities in the intermediate floor without gaps – without the risk of mold.

Alternatively, cellular glass boards are also possible, for example for statically limited structures or in combination with dry screed systems. In solid construction, the insulation is applied directly to the bare ceiling – with impact sound decoupling boards, e.g. made of cellular glass or combined with soft insulation mats. Important: Always plan the installation height, load-bearing capacity and moisture protection.

How can I insulate my floor against noise from below?

Impact sound can be significantly reduced by using suitable insulating materials. The aim is to decouple vibrations between the load-bearing structure and the wear layer.

In old buildings, a combination of rigid thermal insulation (e.g. cellular glass) and a soft impact sound insulation mat or dry screed with integrated sound insulation is particularly effective.

Important: All layers must be laid over the entire surface and carefully decoupled – even small gaps lead to sound bridges. cellular glass has an additional sound-insulating effect due to its mass and can be ideally combined with lightweight structures.

How much does floor insulation cost?

The costs depend on the material, installation height and effort involved in laying. Assuming an insulation thickness of 25 cm, you can expect to pay €25-50 per m².

Note: XPS is petroleum-based, harmful to the environment and often hazardous waste with disposal costs. cellular glass gravel, on the other hand, consists of 100 % recycled glass, is reusable and does not incur any additional costs.

Subsidy programs from BAFA or KfW can significantly reduce the investment – provided they are applied for before the start.