Help & knowledge
Frequently asked questions
Product-related answers on Hemplith® hemp building materials — fundamentals, selection & planning, fire, moisture and sound protection, the individual products, installation and ordering. Can't find your question? Get in touch.
This FAQ provides a product-related overview and does not replace specialist planning, structural or building-physics calculation, approval or system release. Technical values apply only to the product named in each case and to the stated test or calculation assembly.
Fundamentals of hemp building materials
＋ What are hemp building materials?
Hemp building materials use components of industrial hemp — above all fibres and hemp shives — as raw material. Depending on the product they are combined with mineral binders, binding fibres or functional additives. This produces insulation batts, rigid insulation boards, building and plaster-base boards, acoustic panels, loose fills and hemp-lime blocks.
＋ What is the difference between hemp fibres and hemp shives?
Hemp fibres are the long fibres from the outer part of the hemp stalk. They are used above all for flexible and rigid insulation boards. Hemp shives are the light, woody core of the stalk. Among other things they serve as aggregate for hemp-lime blocks, loose fills and building and acoustic boards.
＋ Which Hemplith® product groups are there?
The range includes in particular: Hemplith® Flex (flexible hemp-fibre insulation batt), Hemplith® Therm (more compression-resistant hemp-fibre insulation board), Hemplith® Fill (levelling and loose-fill insulation), Hemplith® Block (hemp-lime block), Hemplith® Drywall (lightweight drywall board), Hemplith® Mineralboard (mineral-bound plaster-base and refurbishment board), Hemplith® Aquaboard (interior board for wet rooms) and Silentlith® acoustic pro (exposed acoustic panel).
＋ Do all Hemplith® products have the same composition?
No. The products differ significantly in raw material, binder, density, strength, reaction to fire and application. A property or a verification for one product must not be transferred wholesale to the entire product family.
＋ Are hemp building materials always entirely plant-based?
No. According to the data sheet, Hemplith® Flex and Therm contain 85% hemp fibres and 15% PES bi-component support fibres. Hemplith® Block combines hemp shives with mineral constituents. Mineralboard, Aquaboard and Silentlith® also use mineral binders. The specific composition must therefore be considered product by product.
＋ Are hemp building materials vapour-open?
Many Hemplith® products have a low water-vapour diffusion resistance and can be used in vapour-open constructions. Whether the entire assembly works in building-physics terms, however, depends on all layers, junctions, climatic conditions and use.
＋ Do hemp building materials regulate indoor humidity?
Several products can absorb and release water vapour sorptively. This can buffer humidity peaks in a room. However, it replaces neither ventilation nor waterproofing and does not eliminate a persistent source of moisture.
＋ Do hemp building materials automatically prevent mould?
No. Certain Hemplith® products have tests or manufacturer's data on mould resistance. Mould can nevertheless occur if surfaces are permanently damp, thermal bridges exist, water penetrates or ventilation is insufficient. Cause and infestation must be assessed by a specialist.
＋ Are hemp building materials suitable for allergy sufferers?
Emission data or an A+ classification are available for individual products. A blanket medical suitability for all allergy sufferers cannot be derived from this. In the case of particular sensitivities, product composition, emission verification and individual requirements should be checked.
＋ Are Hemplith® products formaldehyde-free?
For Flex, Drywall, Mineralboard, Aquaboard and Silentlith®, formaldehyde-free binding or corresponding emission data are stated. The current product-specific verification is always decisive; adhesives, plasters, paints and other materials in the overall assembly must be assessed separately.
＋ Are hemp building materials automatically free of pollutants?
No building material should be described in blanket terms as “free of pollutants”. Declared ingredients and product-related VOC, formaldehyde or AgBB verifications are more meaningful. Auxiliary materials and coatings are also part of the assessment.
＋ Are Hemplith® products recyclable or compostable?
Several data sheets describe the products as recyclable. Whether a specific take-back, material recovery or composting is possible depends on binders, coatings, contamination, dismantling and regional disposal routes. “Compostable” should therefore only be used with robust, product-specific disposal evidence.
＋ Are hemp building materials CO₂-negative?
Hemp binds biogenic carbon as it grows. Whether a finished building product is “CO₂-negative” on balance depends on the system boundary, raw materials, production, transport, service life and end-of-life scenario. This statement should only be made on the basis of a current EPD or a verifiable, product-specific life-cycle assessment.
＋ Do hemp building materials store heat?
Yes, their mass and specific heat capacity can contribute to the thermal storage capacity of a component. Summer heat protection, however, is determined by the complete roof, wall or ceiling assembly, the insulation thickness, window areas, shading and ventilation.
＋ Do hemp building materials also insulate against sound?
Hemp products can absorb sound or support the sound insulation of a component. Sound absorption within a room and airborne or impact sound insulation between rooms are different tasks. Binding values apply only to the respective tested overall assembly.
＋ Are hemp building materials load-bearing?
The Hemplith® boards, insulation materials and hemp-lime blocks described here are not to be treated as load-bearing components without separate verification. According to the data sheet, Hemplith® Block must be mechanically connected to the load-bearing structure. Structure and fixing must be designed structurally.
＋ Can hemp building materials replace conventional building materials?
Often yes, but not across the board and not on the basis of a single characteristic value alone. Application, fire protection, moisture protection, structural design, sound insulation, surface, fixing, approval and cost-effectiveness must suit the project.
＋ New build or refurbishment — where are hemp building materials suitable?
Both are possible. Typical fields are timber-frame and solid construction, roof fit-out, internal insulation, drywall, independent linings, floor and ceiling levelling, acoustics and energy retrofits.
Selection and planning
＋ Which product is suitable for infill panels and between rafters?
Hemplith® Flex is intended as a flexible friction-fit batt for infill panels, cavities and between rafters. It is friction-fitted seamlessly with about 1 cm oversize.
＋ Which product is suitable as a rigid external insulation board?
Hemplith® Therm is described for various internal and external applications, including wall insulation, façade systems, ceilings and mechanically fixed roof applications. For external components, a fully approved system with adhesive, dowels, reinforcement, render and junction details is required.
＋ Which product is suitable for levelling out floor heights?
Hemplith® Fill is intended as a dry levelling and loose-fill insulation beneath dry screed, timber floors or drywall boards. Load-bearing capacity, compaction, layer thickness and load-distributing covering must suit the floor assembly.
＋ Which product combines masonry and insulating effect?
Hemplith® Block is a hemp-lime block for monolithic wall and insulation applications which are not load-bearing across the board. It can be used in solid, frame and timber-frame constructions as well as in refurbishment.
＋ Which board is suitable for lightweight ecological drywall?
Hemplith® Drywall is described for non-load-bearing internal walls, wall and ceiling linings, roof fit-out and as a plaster base for clay or lime plaster. Wet rooms are expressly excluded in the data sheet.
＋ Which board is suitable as a mineral-bound plaster base?
Hemplith® Mineralboard is described for internal walls, ceilings, sloping surfaces, timber joist ceilings, renovations, lime and clay plaster as well as moisture-active internal insulation.
＋ Which board is suitable for bathrooms?
Hemplith® Aquaboard is intended for interior fit-out in wet rooms such as bathrooms. This does not automatically mean that it may be used in areas subject to direct and permanent water exposure without a standard-compliant bonded waterproofing.
＋ Which product visibly improves room acoustics?
Silentlith® acoustic pro is an exposed acoustic panel for walls and ceilings in interiors. It is suitable, for example, for offices, schools, hospitality, hotels, living spaces and studios.
＋ May products be selected on the basis of the λ-value alone?
No. Thermal conductivity is only one selection criterion. Equally relevant are the installation situation, thickness, density, moisture behaviour, compressive and tensile strength, reaction to fire, fixing, sound insulation and the system approval.
＋ What is the difference between λD and the U-value?
λD describes the declared thermal conductivity of a material. The U-value describes the heat transfer through a complete component. A U-value must therefore not be transferred from a single product figure to every construction across the board.
＋ Do I need a vapour control layer with hemp insulation?
That can only be decided for the complete assembly. For use in the thermal envelope, the Flex data sheet requires a windtight, water-repellent layer on the outside and a properly executed vapour-retarding layer — described there as vapour-tight — on the inside. Type and sd-value are to be planned on a project-specific basis.
＋ Is a vapour-open construction automatically safe against moisture?
No. Vapour openness can support the drying reserve, but it does not replace airtightness, driving-rain protection, waterproofing or hygrothermal planning.
＋ When is a WUFI or comparable moisture simulation advisable?
With internal insulation, flat roofs, heavily shaded façades or those exposed to driving rain, unusual layer sequences, high indoor humidity or sensitive timber constructions, a dynamic hygrothermal simulation may be necessary.
＋ How is the material requirement calculated?
Required are the net area or volume, product format, installation thickness, infill dimension, waste, compaction as well as packaging and pallet units. Openings, junctions and reserve must be taken into account separately.
＋ How much waste should be allowed for?
That depends on geometry, laying pattern and product. Rectangular areas often require less reserve than sloping roofs, numerous openings or small-scale infill panels. A blanket percentage should only be set after measurement and laying planning.
＋ Can Hemplith® products be combined with one another?
Yes, for example Flex in the infill panel with a Hemplith® interior board, or Fill in a floor or ceiling assembly. The combination must nevertheless be examined as an overall system; product kinship does not replace a system approval.
Fire, sound and moisture protection
＋ Are hemp building materials combustible?
Reaction to fire differs from product to product. Flex and Therm are stated as C-s2,d0; Mineralboard, Aquaboard, Silentlith® and Block as B-s1,d0. Drywall is stated provisionally as E in the available data sheet. The current declaration of performance or the current test report always applies.
＋ What do B-s1,d0 and C-s2,d0 mean?
The Euroclass describes the reaction to fire of a construction product: the letter assesses the contribution to fire, “s” the smoke development and “d” flaming droplets or particles. This does not yet imply any fire resistance of a wall or ceiling.
＋ Is the reaction-to-fire class the same as F30, F60 or EI60?
No. The reaction-to-fire class assesses the product. F or EI classes assess the fire resistance of a fully tested component assembly including sub-frame, insulation, sheathing, joints and fixing.
＋ Can a single fire certificate be transferred to other thicknesses?
Only if the verification or its classification expressly covers that range. Transfer to other products, thicknesses, fixings or assemblies is not automatically permissible.
＋ Does hemp insulation improve the sound insulation of every wall?
It can damp cavity resonances and support the assembly. The achievable Rw or impact-sound value, however, depends on mass, leaf spacing, decoupling, joints, flanking paths and the execution of the entire component.
＋ What is sound absorption?
Sound absorption reduces reflections and reverberation within a room. It is not the same as sound insulation between two rooms.
＋ What sound absorption values does Silentlith® have?
The value depends strongly on the mounting assembly. For 30 mm panels mounted directly on a surface, the data sheet states αw 0.45. With an air gap or backing, up to αw 0.65 is achieved in the documented test assembly; with 20 mm panels and backing, up to αw 0.70. For planning purposes, the appropriate test assembly must be taken as the basis.
＋ What sound absorption does Hemplith® Flex have?
The data sheet states a weighted sound absorption coefficient αw of 0.70 and class C. Transferability depends on thickness and test assembly.
＋ Can hemp building materials be used in wet rooms?
Product and exposure must match. Aquaboard is intended for wet rooms in interior fit-out. Drywall is not designated for wet rooms. Silentlith® is not suitable for permanently wet areas. Zones subject to direct water exposure require planned waterproofing and suitable surfaces.
＋ Are hemp building materials waterproof?
Moisture-regulating or moisture-resistant does not mean permanently waterproof. Building materials must be protected from standing water, leaks, driving rain and construction moisture unless the approved system assembly reliably handles these actions.
＋ How important is airtightness?
Very important. Air flow can carry considerably more moisture into components than pure vapour diffusion. Airtight junctions, penetrations and transitions must therefore be carefully planned and executed.
＋ Can hemp products be used in mould remediation?
According to the data sheet, Mineralboard is described for mould remediation on mineral substrates. Beforehand, cause, extent and substrate must be clarified, the infestation removed professionally and the source of moisture permanently eliminated.
＋ Do Hemplith® products neutralise pollutants or odours?
Some data sheets state such effects as a product property. For specific statements on individual pollutants, concentrations and long-term effects, however, an appropriate test report is required. Without this, the statement should not be given as a blanket assurance.
Hemplith® Flex
＋ What is Hemplith® Flex?
Hemplith® Flex is a flexible insulation batt of 85% hemp fibres and 15% PES bi-component support fibres for infill panels, roof, wall, drywall and acoustic applications.
＋ What thermal conductivity does Flex have?
The technical data sheet states λD = 0.040 W/(m·K). For calculations, the current declaration of performance, the design value in the relevant jurisdiction and the complete assembly are decisive.
＋ What density does Flex have?
The data sheet states 30 to 40 kg/m³.
＋ How is Flex cut to size?
An insulation saw or an electric handsaw / alligator saw with a serrated blade is suitable. Clean, dimensionally accurate cuts prevent joints and voids.
＋ How is Flex fixed in the infill panel?
According to the data sheet the batt is friction-fitted seamlessly with approximately 1 cm oversize. If required, it can additionally be fixed to rafters with a hand stapler.
＋ May Flex be installed compressed?
Only the intended friction-fit allowance makes sense. Heavy compression, folds, voids or an undersized cut can impair the insulating effect and dimensional stability.
＋ Is Flex suitable for façades?
The data sheet names external façades as an application. However, the batt must not be exposed there unprotected to the weather; wind sealing, water-repellent outer layer, fixing, rear ventilation or render system must be planned as a complete façade assembly.
＋ What fire class does Flex have?
C-s2,d0 according to EN 13501-1:2018 is stated.
＋ How is Flex stored?
Dry and protected from moisture.
Hemplith® Therm
＋ What is Hemplith® Therm?
Therm is a more dimensionally stable hemp-fibre insulation board for thermal and sound insulation. According to the data sheet it consists of 85% hemp fibres and 15% binding fibres; the hemp fibres are described there as treated with soda.
＋ What basic technical values does Therm have?
The data sheet states λD = 0.040 W/(m·K), a density of 85 to 115 kg/m³, compressive stress at 10% deformation of at least 25 kPa and tensile strength parallel to the faces of at least 100 kPa.
＋ Which dimensions and thicknesses are available?
The standard format is 1,100 × 600 mm. Thicknesses of 30 to 160 mm are stated; from 100 mm the boards are supplied as bonded composite boards according to the data sheet.
＋ Can Therm be used in an ETICS?
The data sheet describes an ETICS application. A legally compliant execution, however, requires an approved or released overall system with defined adhesive, dowels, reinforcement, top coat, plinth and junction details.
＋ How are Therm boards laid?
The boards are butted tightly from bottom to top, laid offset, aligned and plumb. According to the data sheet, joints under 5 mm should be filled with loose hemp wool; larger joints are to be avoided.
＋ Do Therm boards have to be dowelled?
For the rendered external assembly described in the data sheet, dowelling is required irrespective of the substrate. Dowel type, number and setting pattern must suit the system and the substrate.
＋ What fire class does Therm have?
C-s2,d0 according to EN 13501-1:2018 is stated.
＋ Can Therm be used on flat roofs?
The data sheet names mechanically fixed flat-roof and loft applications. Because of the high moisture and safety requirements, a fully verified roof assembly is necessary for this; naming the product alone is not an approval for every flat roof.
Hemplith® Fill
＋ What is Hemplith® Fill?
Fill is a levelling and loose-fill insulation of cleaned, mineral-treated hemp shives.
＋ Where is Fill used?
Named are floor-levelling fills beneath dry screed, timber floors or drywall boards, tapered insulation on ceilings or flat roofs, and cavity fills in joist floors, timber frames or half-timbering.
＋ What density and thermal conductivity does Fill have?
The technical data sheet states approximately 175 to 200 kg/m³ and λ = 0.060 W/(m·K). The product catalogue states differing values. Until this is clarified, the characteristic values must be confirmed in writing on the basis of the current product version before tendering or calculation.
＋ Which layer thicknesses are possible?
The data sheet states typical layer thicknesses of 20 to 200 mm. Whether this thickness works without inadmissible settlement or deformation depends on the assembly, the compaction and the load distribution.
＋ How is Fill installed?
Pour in dry, level off and, depending on the assembly, compact or build over with a suitable board. For bonded layers, the data sheet mentions the possible addition of a hemp-lime binder or mineral lightweight binder; mixing ratio and approval must be defined.
＋ Can Fill be walked on or loaded directly?
Not as a finished wearing layer. Loads must be transferred via a dry screed, timber floor or another suitable load-distributing layer planned for that purpose.
＋ Is Fill non-combustible?
The data sheet contains a contradictory wording on this (“non-combustible” and at the same time B-s1,d0). B-s1,d0 is not the same as “non-combustible”. Until an unambiguous, current verification is available, only the documented classification with its precise scope should be used.
＋ Is Fill settlement-proof?
A blanket freedom from settlement is not substantiated. Installed density, compaction, cavity height, moisture and covering must be defined and checked on site.
Hemplith® Block
＋ What is Hemplith® Block?
Hemplith® Block is a hemp-lime block that combines insulating and masonry functions in one element. The data sheet names hemp shives, lime, clay and water as constituents.
＋ Is Hemplith® Block load-bearing masonry?
Not without project-specific structural and building-authority verification. The data sheet requires a mechanical connection to the load-bearing structure and typically names 4 to 5 anchors per square metre.
＋ Which applications does the data sheet name?
Monolithic external walls, internal insulation, acoustically effective partition walls and sub-floor insulation as well as applications in solid, frame and timber-frame constructions.
＋ What thermal conductivity does the Block have?
For the dry state, the data sheet states λ = 0.069 W/(m·K). The design value for a specific component must take into account moisture, mortar joints, plasters and the applicable design approach.
＋ What density does the Block have?
A dry bulk density of 318 ± 10 kg/m³ is stated.
＋ Which formats are available?
The data sheet lists thicknesses of 70, 110, 150, 200, 250, 285 and 320 mm. The standard base size is stated as 590 × 285 mm; for the 285 mm variant a special base size of 590 × 320 mm is named. The delivery dimensions should be clearly confirmed in the quotation.
＋ What U-values does a Block wall achieve?
Depending on thickness, the data sheet states calculated values of 0.91 to 0.21 W/(m²·K). These values must not be used unchecked as the U-value of the finished component, because mortar, plasters, junctions, moisture and calculation method must be taken into account.
＋ What fire class does Hemplith® Block have?
The data sheet states B-s1,d0 according to EN 13501-1. This is a product classification and not a fire-resistance verification for a wall.
＋ How are the blocks laid?
The data sheet describes a bond with an overlap of at least one block thickness and a joint width of about 3 mm. The first course is levelled horizontally in a 1 to 2 cm thick bed of levelling mortar. Before installation, the blocks should be briefly moistened.
＋ Which mortar is used?
Hemp-lime masonry mortar for internal walls and lime insulating masonry mortar for external walls are named. The approved system for the specific project is decisive.
＋ Which plasters are suitable?
The data sheet requires vapour-open lime or clay plaster systems. Plinths, splash-water areas and external surfaces require separate, moisture-safe details.
＋ How is the base of the wall executed?
For external walls and damp substrates, a damp-proof course is provided beneath the first course of blocks. In addition, plinth height, splash water, connection to the ground, waterproofing and thermal bridges must be planned on a project-specific basis.
＋ How are openings spanned?
For lintels the data sheet states a bearing of at least 20 cm per side, and at least 30 cm for spans over 2 m. Lintel, bearing and load-bearing structure must be structurally designed.
＋ Are the stated maximum wall heights binding?
No, not without clarification of the structural system and the valid verification. The table is a manufacturer's statement; wind load, bracing, anchors, openings and building regulations must be taken into account.
＋ How are Hemplith® blocks stored?
Dry, protected from rain and ventilated. The data sheet states up to six months of outdoor storage with rain protection and up to two years of indoor storage. Pallets should not be wrapped airtight.
＋ What must be observed for the PL block and FR block?
The available German data sheets contain largely identical product values, but at the same time individual table and designation errors. Before publication, tendering or structural use, product identity, differences between variants, compressive strength and primary verifications must be clearly clarified.
Drywall, plaster-base and wet-room boards
＋ What distinguishes Drywall, Mineralboard and Aquaboard?
Drywall is a lightweight interior board with about 320 kg/m³ and a provisional fire class E. Mineralboard is mineral-bound, denser and stated as B-s1,d0; it is described in particular as a plaster base and refurbishment board. At about 620 kg/m³, Aquaboard is the densest of the three and is intended for interior fit-out in wet rooms.
＋ Which formats does Drywall have?
The data sheet states 800 × 1,200 mm in 18 and 30 mm thickness.
＋ How is Drywall fixed?
On timber or metal studs with coarse-threaded drywall or wood screws; centre spacings of 30 to 60 cm and screw spacings of 20 to 25 cm are stated. The specific sub-frame must be determined according to loading and surface.
＋ Can Drywall be wallpapered?
The Drywall data sheet names paint, wallpaper as well as clay and lime plaster as possible surfaces. Beforehand, joint treatment, priming and the compatibility of the complete coating system must be clarified.
＋ Which formats does Mineralboard have?
The data sheet states 1,200 × 600 mm in 20 and 30 mm thickness; other formats are possible on request.
＋ How close must the sub-frame be for Mineralboard?
The data sheet states a maximum stud spacing of 40 cm on walls and a maximum of 30 cm on ceilings or slopes. Per board, 9 fixing points on walls and 12 on ceilings or roof slopes are stated.
＋ Which coatings are suitable for Mineralboard?
Vapour-open lime or clay plasters and vapour-open paints are intended. For the plaster assembly described, the data sheet excludes dispersion and latex paints, wallpaper and dense coatings.
＋ How is Mineralboard bonded in internal insulation?
The data sheet describes full-surface bonding with vapour-open reinforcing or adhesive mortar, tightly butted bonded laying and a board offset of at least 30 cm. Substrate and moisture safety of the overall assembly must be checked beforehand.
＋ What dimensions does Aquaboard have?
The data sheet states 1,200 × 800 mm at 19 mm thickness; other formats are possible on request.
＋ How is Aquaboard fixed?
On a drywall sub-frame with a maximum stud spacing of 60 cm on walls and 40 cm on ceilings or roof slopes. Stated are 9 fixing points per board on walls and 12 with washers on ceilings or slopes.
＋ May Aquaboard be installed wet?
No. The data sheet expressly requires that the boards not be installed in a damp condition. Substrate and boards must be dry.
＋ Does Aquaboard require waterproofing in the shower area?
Yes — if the surface is directly exposed to splash or service water, a standard-compliant bonded waterproofing with approved system components is required. The board's suitability for wet rooms does not replace the waterproofing.
＋ Can heavy loads be fixed directly to the boards?
Heavy sanitary fittings, cabinets or brackets should be anchored in the load-bearing sub-frame or in planned reinforcements. The boards alone are not approved across the board as a load-bearing fixing base.
＋ How are board joints executed?
Boards are laid in a bond; cross joints are to be avoided. Free joints require backing. Joint treatment and, where applicable, reinforcement depend on the board type and surface system.
＋ How are the boards cut to size?
Depending on the product, hand saws, jigsaws, circular saws or band saws and standard drywall tools are suitable. Dust extraction and personal protective equipment must be chosen according to tool, dust generation and site situation.
＋ How are Hemplith® boards stored and transported?
Dry, flat and lying down, on a firm base and protected from ground moisture, soiling and weather. Damaged or damp boards must not be installed without checking.
Silentlith® acoustic pro
＋ What is Silentlith® acoustic pro?
An exposed acoustic panel of hemp shives and a cement-free mineral binder for interior wall and ceiling surfaces.
＋ Which formats are available?
The data sheet states 600 × 600 mm, 625 × 625 mm and 1,200 × 600 mm in 20 and 30 mm thickness.
＋ What fire class does Silentlith® have?
B-s1,d0 according to EN 13501-1 is stated.
＋ Can Silentlith® be used outdoors?
Not in unprotected external areas, under direct weathering or in permanently wet areas. An application in protected special areas would have to be approved separately.
＋ How is Silentlith® mounted?
With screws and washers or a concealed mounting system on a timber or metal sub-frame. The data sheet recommends a maximum centre spacing of 40 cm on wall and ceiling; direct mounting is possible on load-bearing, level substrates.
＋ When may Silentlith® be mounted?
Only after moisture-intensive construction work has been completed and under controlled temperature and humidity. The panels must be stored dry, clean, well ventilated and lying flat.
＋ Can the acoustic effect be improved by an air gap?
Yes. The test data show that spacing and absorbent backing can significantly change the frequency-dependent effect. The desired reverberation time should therefore be planned in room-acoustic terms.
＋ How much acoustic area is needed?
That depends on room volume, existing surfaces, use, occupancy and target reverberation time. A blanket square-metre figure without a room-acoustic calculation is not credible.
Installation, site and quality assurance
＋ Must natural building materials be installed dry?
Yes. Products and substrates must be checked for moisture, cleanliness and suitability before installation. Trapped construction moisture can cause damage even with vapour-open materials.
＋ Which substrates are suitable?
Substrates must be load-bearing, level, clean and sufficiently dry. Loose, chalking or dense old coatings may have to be removed depending on the system. Highly absorbent substrates may require a compatible, vapour-open pre-treatment.
＋ Can work be built up on old dispersion or latex paint?
For Mineralboard, the data sheet requires the complete removal of loose old coatings as well as dispersion, oil and latex paints. The existing substrate must be checked on site.
＋ Why are vapour-open plasters and paints important?
Very dense coatings can restrict the moisture buffering and drying of the construction. Lime and clay surfaces are often suitable, but must be matched to the respective board system in terms of adhesion, strength and use.
＋ How are services routed in block walls?
The Block data sheet describes chases cut with a wall chaser and subsequently filled with crushed block material and binder. Chase depth, cable/pipe routing and structural effects must be planned.
＋ Which site checks are advisable?
Advisable are, among others: checking product, batch and delivery documents; ensuring dry and level storage; documenting substrate moisture and load-bearing capacity; checking centre, screw and dowel spacings; photographically documenting joints, junctions, air and wind sealing; checking plaster and adhesive systems for approval and compatibility; with loose fills, checking installation height, compaction and evenness.
＋ Can damaged boards or blocks be used?
Small offcuts can be used depending on the application. Cracked, soaked, deformed or structurally damaged products must not be installed in safety- or function-relevant areas without expert assessment.
＋ Which personal protective measures are required?
The usual occupational safety rules apply even to natural building materials that are pleasant to work with. When sawing or sanding, dust extraction, safety goggles and — depending on dust exposure — respiratory protection are advisable; manufacturer's instructions and the risk assessment take precedence.
＋ What must be observed on winter sites?
Adhesives, mortars and plasters require permissible substrate and air temperatures as well as adequate drying conditions. Frost, condensation and excessive construction moisture can impair adhesion and durability.
＋ How are complaints avoided?
Through unambiguous product and batch designation, system components confirmed in writing, documented substrate testing, a sample area, agreed details and photographic documentation of the concealed work.
Verifications, tendering and advice
＋ Which documents should be available before execution?
Depending on product and application: current technical data sheet, declaration of performance, ETA or national approval, fire and emission verifications, installation guideline, system approval, safety information as well as, where applicable, an EPD and project-specific structural or building-physics documentation.
＋ What is an ETA?
A European Technical Assessment describes the assessed essential characteristics of a construction product on the basis of a European Assessment Document. It is not a blanket verification for every conceivable component assembly.
＋ Does Hemplith® Flex have an ETA?
The data sheet names ETA 24/0170; the ETA dated 13 May 2024 is available in the project folder. For tendering and CE documentation, product identity, the current version and the associated declaration of performance must be reconciled.
＋ May a data sheet be used as an approval?
No. A data sheet provides information about the product. Usability under building regulations and the applicable verifications arise from the documents intended for that purpose and from the applicable jurisdiction.
＋ How should technical values be specified in tenders?
Always with product designation, standard or test method, unit, thickness or variant, document version and, where applicable, test assembly. Vague marketing terms should be replaced by measurable or testable requirements.
＋ What must be observed regarding environmental claims in quotations?
Terms such as “climate-neutral”, “CO₂-negative”, “compostable”, “free of pollutants” or “suitable for allergy sufferers” require a clear definition and robust evidence. Safer are specific statements on the biogenic raw-material share, emissions, EPD results and the dismantling route.
＋ Why can technical values in the catalogue and the data sheet differ?
Documents can use different versions, variants or calculation bases. In the event of contradictions, the more favourable value does not automatically take precedence. Product identity and the current primary source must be clarified.
＋ Who decides on suitability in the specific building project?
Manufacturers and distributors supply product and system information. Project-specific selection and verification lie — depending on the task and the legal situation — with the specialist designers, structural engineers, building physicists, fire-safety planners, the executing specialist contractor and the site management.
Ordering, delivery and advice
＋ Which information is needed for a product recommendation?
Helpful are: component and location in the building; new build or refurbishment; the existing complete layer assembly; dimensions, area, thickness and stud spacings; substrate and load-bearing structure; indoor and outdoor climate or use; requirements for heat, moisture, fire and sound; desired surface; building location and applicable jurisdiction; schedule, delivery route and site logistics.
＋ Can quantities be ordered directly from the area?
Only after conversion into boards, batts, volume, containers or pallets and after taking waste, openings, compaction and reserve into account. For block masonry, mortar and supplementary products are added.
＋ What must be observed regarding pallets and storage space?
Access, unloading equipment, permissible floor load, a dry level standing area, rain protection and the construction schedule must be clarified before delivery. Natural-fibre products must not be left permanently unprotected outdoors.
＋ Are special formats available?
Several data sheets mention special formats on request. Availability, minimum quantity, delivery time, price and the technical validity of the verifications must be confirmed in writing before ordering.
＋ Where is technical advice available?
von Hanf Handels GmbH & Co. KG, Fraunhoferstrasse 3, 25524 Itzehoe, Germany, phone +49 (0)4893 2540483, e-mail info@vonhanf.de, web www.vonhanf.de. For sound advice, component sketches, dimensions, photos and any existing verifications should be sent along.
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We advise you personally on material, wall assembly and logistics.