Clayworks Clay Panels

1. OVERVIEW

Overview

Clayworks Clay Panels are vapour diffusion, open clay plaster dry-lining boards. They are the only clay panel systems with a sandwich construction, consisting of a soft fibreboard (DIN EN 18986), clay plaster and glass fibre reinforcing tape. All four edges are tapered.

The panels are designed to be finished with Clayworks Clay Plaster Colours and Textures of choice and have all of the Health, Sustainability and Performance benefits of clay when used as an internal building material: breathability, no VOCs, no toxins, no off-gassing, humidity control, thermal and acoustic properties.

The composition enables consistent and reliable products with an extremely small deviation in the boards’ thickness compared to other systems.

2. DIMENSIONS & KEY DATA

•  Dimensions: 115 x 62.5 x 3.1 cm

•  Surface area: 0.72 m²

•  Weight: 15 kg/plate

•  Density: 6.7 · 10² kg / m³ (average)

•  Vapour diffusion: μges <7

3. BENEFITS

Easy to work with:

•  The panels are as easy to work with as plasterboard &  thereby suitable for experienced handymen and all good tradespeople.
•  Fibre Board panel is lighter and easier to man handle. Both system types require skimming and potential need for scrim tape and so on.
•  Boards join together smoothly so that (unlike with many other systems) full-face clay plastering is not necessary to hide joints between boards, contributing to up to 40% time savings compared to other systems.
•  Additional time savings if boards are glued to the wall (rather than screwed or stapled). Can be glued to cement walls and gypsum boards.
•  No plugging necessary.
•  They can be easily cut to size with a circular saw.
•  They can be directly screwed or stapled to wooden studs under
construction or stuck to a brick wall or concrete with a mineral lime
adhesive.
•  Reinforcing tape is stapled to the joints and filled with jointing material.
•  Once dried, a clay plaster finish is applied, which can be a colour and texture of choice.

Performance

•  Acoustics: excellent sound insulation.
•  Thermal insulation: (see below) the core of the Panel is a 17 mm wood fibreboard which provides good basic insulation.
•  A good solution for embrasures with cracks: the system avoids contact with the construction wall and hence cracks in the surface
•  High inherent stability – excellent for stud constructions without support.
•  Humidity Regulation: the boards + clay plaster help to keep a room at about 50%, optimum for helping to prevent asthma as this helps to keep the mucous membrane from drying out.
•  Absorbs and stores indoor air pollution.
•  Absorbs and stores odours and smells and ionises the air, contributing to a feeling of fresh air.
•  Energy-efficient: the panels store warmth during the day and release it slowly in the night.
•  Extremely low levels of primary operational energy are used in
manufacturing.
•  Sustainable materials primarily used in construction – wood and clay.

4. THERMAL CONDUCTIVITY OF CLAYWORKS CLAY BOARDS

The calculations are based on the following;

The fibre board thickness is 17mm within the clay sandwich see below;

λ = 0.073 W. m-1 .m-1
Overall panel thickness is 31mm.
Makeup is fibre board (17 mm) & clay plaster sandwich 31 mm o/a.

Where λ is the ‘thermal conductivity’

•  R values go up as insulation gets better whilst U values go down. The U VALUE is in essence the reciprocal of the RVALUE . The lower the UVALUE the better.
•  Thermal conductivity has been stated as λ = 0.073 W. m -1 .m -1 (or W/m.K) which in turn implies that the U value (thermal transmittance) is implied by ;
•  R = l/λ where l is the material (see below) thickness of
⇒  R = 0.031/0.073 = 0.42 K.m 2 /W

Where R is thermal resistance

•   The UVALUE is simply the inverse of the R VALUE plus the internal and external convection and radiation heat losses inter alia …
•  I.e. UVALUE = 1/[R VALUE + R si + R 1 + R 2 … + R so ] where the common value of R si is 0.12 K.m2 /W &amp; R so is 0.06 K.m2 /W.
∴ UVALUE = 1/[0.42 + 0.12 + 0.06] = 1.667 W/m 2 .K min
•  The UVALUE would decrease (a good thing!) when you include whatever wall type the panel is added to
•  For example if the Clayworks clay/fibre-board panel was added to a solid 9” brick
wall (where R9”- BRICK = 1.8 K.m2/W)
∴ UVALUE = 1/[0.42 + 0.12 + 1.8 + 0.06] = 0.416 W/m2.K

If the clay panel is looked at in isolation i.e. without the additional thermal resistances;

UVALUE = 1/[0.42] = 2.38 W/m2.K

Clayworks Clay Board + 10mm of Clayworks clay plaster
With the additional layer of 10mm Clayworks clay plaster applied to the 31mm fibre board note the following;

10mm Clay (λ) = 0.76 W. m-1 .m-1
R 10mm CLAY-PLASTER = 0.010/0.76 = 0.0132 K.m2/W
Σ UVALUE of 10mm Clayworks plaster + 31 mm fibre board = 1/[0.0132 + 0.42] = 2.37 W/m2.K

Conclusions
For comparison an unfilled 10” brickwork cavity wall (built prior to 1900) will have a U-value of around 2.0 W/m2.K

As a comparison, the calculations give us the U value of a simple cavity wall from the 1800s – it has a U value of 2 so not much better than the clay panel. Sitting in a house made just from clay panels you wouldn’t feel much colder than in your average Victorian building.

5. RANGE OF USE

Anywhere within a building except for areas where there is running water. The panels are especially suitable for bathrooms as the clay system absorbs the humidity.

In a kitchen, the clay plaster significantly decreases the build-up of grease, which tends to occur over time in all kitchens.

6. INSTALLATION

•  Fixed with staggered joints on OSB clad walls or timber/metal framed (w = 6 cm) studs at 62.5 cm centres.
•  On ceilings or to the underside of rafters 31,25 cm centres apart. Can also be fixed to a solid substrate using an adhesive.
•  Fixing materials: drywall screws (3,9 x 45 mm) or galvanized staples (length 50 mm or longer, width 10 mm or more, wire gauge 1,4 mm or more).
•  Fixing distance: approx. 15 cm apart on all tapered edges. On ceilings or the underside of rafters, an additional row through the middle of the length of the board is required.

Installation instructions

1. Cut the clay board with a standard circular hand saw.
2. Mount the board to the wall: The boards are either screwed or stapled to the sub-construction or they are glued to brick walls or gypsum boards.
3. Staple the mach on the joints to avoid later on cracks between the joints of the boards, a 10 cm mach is stapled over the joints.
4. Wet the joints: It is easier to fill up the joints with clay plaster when the joints are wet.
5. Fill up the joints: If there is material left over when dry, it will be shaped off.
6. Apply thin layer of clay finish plaster 0.5mm.
7. Apply the preferred clay plaster finish.

7. SUB-CONSTRUCTION PREPARATION

Stud Walls
The panels are screwed to studs with a spacing of 62.5 cm.

Ceilings
The spacing for ceiling or roof slopes is 31.25 cm.

Wood walls
The panels can be screwed to the wall.

Brick walls or gypsum boards
The panels can be glued without plugging.

8. SERVICES

Wiring within the panels is not possible, but drilling through them for lights, sockets and so on is. We recommend running any services behind the panels and marking out locations of any fittings prior to applying the finish plaster.

Backing boards
Wood fibre board can be placed behind the panels for stability and added acoustic and thermal performance. The Clayworks Clay Panels can be glued to any flat solid surface such as concrete walls and ceilings but for masonry we would recommend a soft wood subframe which allows for even spacing of screws to fix the boards. The subframe also creates a space to run services.

Fixings (for example picture frames)
In the same way you would for any plastered wall, you can put nails and screws in the wall. For heavier items such as built in floating cabinets or shelves, we recommend plywood backing, but we can look at the project in detail and advise.

9. FIRE RATING

Clayworks Clay Panels are not yet fire rated. The clay plaster itself is BRE Class 1 fire rated (also fulfilling the requirements for Class 0 as outlined in the Building Regulations).