Limecrete

The use of limecrete is desirable in a historic building as it allows naturally occurring moisture to escape through the floor. The use of modern cement floors has caused some problems as moisture is unable to escape through the floor and is pushed towards the walls and can cause damp patches to occur in or around the base of the wall.

Limecrete floors offer an alternative to impervious, non flexible cement concrete floors.These floors are also chosen for ecological new builds using natural materials such as straw and wood because it uses less energy in production, avoids the use of cement and is recyclable at the end of its useful life.

‍Glapor recycled foam glass insulation may be used in conjunction with a limecrete slab for insulating values. Glapor Foam Glass Aggregate is an insulation material for underground use. Recycled foam glass aggregate saves energy and also contributes to a comfortable indoor environment.

Glapor is a high quality foamed glass gravel made from 100% recycled glass. It is a versatile material; lightweight, load bearing and thermally insulating, making it an excellent material for a variety of ground based applications.

Glapor comes as an aggregate which allows it to be installed incredibly quickly. It is permanently stable, has a strong resistance to insects and rodents and has excellent compressive strength.

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A base of clean hardcore (minimum depth 150mm) may be used. It should be well compacted down by use of a vibrating plate. A limecrete floor requires no D.P.M. (damp proof membrane) as the lime method is to allow moisture to breathe through a structure.

Limecrete can be laid in layers of 100mm.. Greater thicknesses are achieved by adding subsequent layers to build up the desired thickness.

Limecrete should be mixed to the consistency of a floor screed i.e., a semi-dry state, which will hold together when squeezed by hand, wet traditional concrete type mixes will result in excessive shrinkage. If possible a screed mixer or roller pan mill should be used and drum cement mixers tend to result in the mix balling.

Fibres are added to provide greater strength, sooner, without compromising the breath-ability or life of the limecrete.

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The limecrete can be finished by tamping with a wooden or steel tamper and the surface can be rubbed up using either a timber or polyurethane float.

Limecrete floors are fully compatible with under floor heating. When covering the water pipes then a 75mm layer of limecrete is necessary. It is essential that when the under floor heating is commissioned the amount of heat directed to the pipes within the limecrete is very gradually increased to minimise shrinkage.

Once laid limecrete should be kept damp for 96 hours (minimum). This may call for spraying with water during warm and hot periods. Limecrete must always be protected from freezing conditions for the first 10 days after laying. Traffic should be avoided for 10 days, and thereafter protective boards should cover the work for 3 weeks before exposure to general traffic.

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When selecting a floor covering it is important to select a material that continues the ability of the floor to breath such as natural stone or terracotta tiles. Timber floors are also an option but it is best to lay the wooden boards on treated timber battens to allow a air gap and to incorporate vents to allow a degree of air exchange.

A point to keep in mind when installing a limecrete floor is that it should not be used to support masonry walls or chimneys. Suitable foundations need to be planned and put in place before the limecrete floor is laid. Lighter timber stud walls may be acceptable.

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Installation Instructions:

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1: Base Substrate Preparation.‍

When the existing floor has been removed, excavate ground to required depth. It is important to level and compact the surface as variations in levels can increase material consumption. A laser level may be used to ensure ground is level.

2: Geotextile Membrane‍

Once level and clean lay the geotextile membrane on top on the substrate. Make sure the joints of the membrane overlap. Leave enough membrane on the edges to be able to fold onto the top of the Glapor (SG600P) base.

The Glapor is your hardcore, insulation and main construction layer.
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‍3. Markers‍

It is advisable to install marker posts to indicate the finished level after compaction. A compaction factor of 30% is required. (i.e 300mm compacted to 230mm)

4. Glapor Recycled Foam Glass

Introduce the Glapor gravel into the prepared area. Glapor bulk bags should be emptied manually, or with mechanical assistance. Glapor bulk bags have a release at the base of the bags.

The max depth of Glapor to install at a time is 300mm compacted to 230mm. If more depth is required it should be laid in layers.

Remember the minimum recommended depth of Glapor is 120mm after compaction.

‍5. Distribution‍

Use a rake or shovel to spread the Glapor evenly across the whole area.

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‍6. Compaction‍

Using a vibrating whacker plate (circa 80 to 120kg whacker plate) compact the Glapor base down to your finish level.

Once Glapor is compacted and level fold over the rest of the bottom layer of membrane then lay your next geotextile membrane on top, taking care to overlap joints.

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‍7. Underfloor Heating‍

If installing underfloor heating, now is the time to fit your underfloor heating system on top of membrane taking care not to puncture the membrane.
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‍8. Perimeter Board

Fit the cork perimeter board around the edge of your floor area making sure that the cork board finishes at your final floor level height.

Cork boards are supplied in 1000mm X 500mm sheets and will need to be cut to size on site.
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‍9. Limecrete

Mix limecrete at 2 parts limecrete aggregate to 1 part Roundtower NHL 5 by volume, adding sufficient water to make a stiff but workable mix. Reinforcement fibres are recommended. (1 bag per tonne of aggregate). Ideally mix for 20 minutes after adding sufficient water.

(Perimeter edging can be used to screed or insert shuttering to thickness of slab)

When laying the limecrete finish, tamp with a wooden or steel tamper. Float with a timber or polyurethane float.

The final surface should be screeded and tamped in a float screeding manor, then scoured with the float and trowelled.

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10. Aftercare‍

Limecrete should always be kept damp for a minimum of 96 hours and protected from freezing conditions for the first 10 days after laying.
If you have installed underfloor heating this should not be used for a minimum of 4 weeks. Follow suppliers guidelines.

Explore the Roundtower limecrete floor system.