Problems of disposal
Plasterboard has been something of a problem for eventual disposal because of the high levels of sulphate and the plasterboard industry has generally been slow to implement a recycling strategy.
Indeed the plasterboard manufacturers can hardly be said to be transparent about their policies and in the past and the almost national monopolies of these companies have come into question. In 2002 the four main plasterboard manufacturers (BPB, Knauf, Lafarge and Gyproc) were given enormous fines by the EU for price fixing through a cartel extending throughout most of Europe. This gives an indication of how some of the largest materials suppliers work together and may be too entrenched in their manner of operation to want to see change.
In England and Wales, since the 1st of April 2009, high sulphate wastes sent to landfill must go to a ‘high sulphate monocell’ specifically designed for sulphate wastes,
There are, however, government initiatives afoot in the form of the Plasterboard Sustainability Action Plan to encourage industry to recycle more of the million tons a year of plasterboard waste, or alternately some suppliers have put in place their own recycling schemes, eg Siniat whose web site says “Scheme available to merchants, distributors and contractors” so it’s not clear whether small amounts would be collected.
The Plasterboard Sustainability Partnership page on recycling says:
but this does not make clear whether small batches of plasterboard would be collected from a self build site.
The other alternative is the local authority recycling centre but it is very difficult to get clear information about whether they send it to a high sulphate monocell or whether they send it for recycling. Best to check with them.
Other environmental issues
There are several ways in which internal walls impact on environmental issues –
- the sustainability of the materials – see Building materials and life cycle analysis / Plasterboard.
- risk of reducing air tightnessA measure of how leaky a building is to air. In other words, how draughty it might be. There are now standard fan pressure tests to check how air tight a house is and the Building Regulations have minimum standards for all new houses (L1A – Conservation of fuel and power in new dwellings (England)). A much higher degree of air tightness is covered by the Passivhaus standard
- the embodied energythe total amount of energy it takes to make a material (or a building). See more on embodied energy of the materials
- indoor pollution – see Avoiding pollution
- their permanence or adaptability – see Flexible design
- their thermal massthis is about how much heat something can absorb - so it involves its specific heat capacity and its volume. It can be useful for levelling out the peaks and troughs of temperature within a house. See the page on thermal mass
Other factors to consider are
- fire resistance[for the purposes of part B of the Approved Documents] - The ability of a component or construction of a building to satisfy, for a stated period of time, some or all of the appropriate criteria specified in the relevant part of BSBritish Standard 476. (if it is a separating wall[for the purposes of part E (sound) of the Approved Documents] - Wall that separates adjoining dwelling-houses, flats or rooms for residential purposes.) and spread of flame
- sound resistance
- running of services
Whether to use plasterboard
The main uses of plasterboard are:
- Providing fire resistance to walls and ceilings. The Building RegulationsThese are the mass of regulations that cover safety, health, welfare, convenience, energy efficiency etc. in the way buildings are constructed. Not to be confused with Planning consent (which is more to do with whether you can put up the building in the first place). See more on the regulations , Approved Document part BThe Approved documentsApproved documents (England) are detailed publications which come under the English Building Regulations. They are based on tried and tested methods of building and if you follow them you are assured of complying with the Regs. The equivalents for Scotland are the Technical HandbookUnder the Scottish Building Regulations, the Technical Handbook gives construction principles, which, if you follow them guarantee compliance with the Regulations, for Wales: the Approved documents (Wales), and for N.I. the Technical BookletsUnder the Northern Ireland Building Regulations, the Technical Booklets give construction principles, which, if you follow them guarantee compliance with the Regulations, (England) part B, deals with fire (sections B2 and B3) stipulates how much fire resistance different parts of a building require and what the Spread of Flame limitations are. It is very often possible to achieve the requirements by adding one or more layers of plasterboard.
- Creating a flat smooth surface which can be plastered or decorated directly. Plasterboard is paper faced with one side being of relatively good quality so that it can take paint directly. This is the method of finish being adopted by many of the SIPSStructural Insulated Panels - prefabricated (usually in a factory) timber panels often forming part of an integrated building system and aimed at fast site erection. see more on SIPs manufacturers and by Walter Seagal self builders. The more traditional method is to hand apply two coats of plaster (undercoat of browning, top coat of finish) and then decorate. If the former method is used then joints are normally feather edged and taped and filled (or simply covered with a timber cover strip); if the traditional method is used then they are simply taped.
- Adding acoustic insulation
- Adding thermal mass. This is a slightly controversial subject because it has been and still is somewhat difficult to quantify although upcoming software is getting better at it. Thermal mass is normally a very useful component in stabilizing temperatures in a building because excess heat goes into the walls and ceilings and is stored there until the temperature drops. What is difficult to calculate is how deep it goes into the surfaces before it starts coming out again. See Thermal Mass. Arguably the diurnal temperature cycle is the most important one in this context and although the layer of thermal mass provided by plasterboard (and plaster) is relatively thin, it is situated in the optimum location to have the maximum effect (on the surface). For instance the total mass of plasterboard used in a two storey[for the purposes of part B (fire) of the Approved Documents to the Building Regulations] this includes - (a) any gallery[for the purposes of part B of the Approved Documents] - A raised area or platform around the sides or at the back of a room which provides extra space. if its area is more than half that of the space into which it projects; and (b) a roof, unless it is accessible only for maintenance and repair. four bedroom timber frame house (as required for fire protection) may well be around 3 – 5 tonnes, which gives considerable thermal mass
One of the deciding factors with internal wall[for the purposes of part E of the Approved Documents] - Any wall that does not have a separating function. construction is whether, and to what extent the wall needs to be load bearing. The qualities of high thermal mass and acoustic insulation tend to work together with heavyweight materials. Of the traditional methods for internal wall building, both concrete block and brick rate quite poorly in terms of embodied energy, sustainability and adaptability though they both score well on fire, thermal mass and sound reduction.
Plasterboard walls are relatively easy to alter and remove, providing the floor level is consistent between rooms. Plasterboard is low in thermal mass (and not so good for sound insulation unless it is filled with acoustic mineral fibre). BASF has been developing gypsum based wall boards which incorporate microcapsules of phase changeswitching from liquid to solid at a certain temperature and thus releasing latent heat. In the case of certain building materials, this can be made to happen at, say, 20 deg. Celsius. The reverse also happens so these materials will effectively have a higher thermal mass than normal and can be used to store heat as they are warming up and release it as they cool down, This keeps them at a more stable temperature. (eutectic) wax substances (PCMs) which increase the effective thermal mass very considerably. See Knauf Comfortboard. Plasterboard can achieve high fire resistance if extra layers are added.
With stud walling there may sometimes be a risk of compromising air tightness, especially with timber frame construction (see Air Tightness). This can occur if the joints with the adjoining external walls, floor and ceiling[for the purposes of part B of the Approved Documents] - A part of a building which encloses and is exposed overhead in a room, protected shaft or circulation space. (The soffit of a rooflight is included as part of the surface of the ceiling, but not the frame. An upstand below a rooflight would be considered as a wall.) are not properly sealed and the joint also hides a break in the external construction thus allowing cold air to move straight into a ‘cooling fin’ within the house.
Alternatives to plasterboard
There have been several fairly recent developments in dry lining boards for internal walls. Traditional plasterboard is being challenged by other variations of gypsum based boards and also by clay based lining boards. Lining boards usually have to have a degree of fire resistance both structurally and with regard to the spread of flame (Building Regulations: Linings and Structure) and this limits the materials that can be used.
An added factor driving the change is that plasterboard has so little strength before it is fixed and damaged boards tend to litter many a building site so some of the newer boards tend to be less brittle and also tend to have a better finish. Most of the newer boards come from northern Europe and are still being imported which adds to the embodied energy and cost. Another factor is thermal mass; the newer boards help maintain thermal stability.
There are more eco-friendly alternatives to plasterboard such as:
Fermacell is a gypsum/cellulose lining board made in Germany to a high ecological standard using recycled materials.
Heraklith BM is a wood wool based building board which can be used as an all-in-one solution.
Breathaboard by Adaptavate. “All components are natural and sustainable. Breathaboard is completely biodegradable and non-toxic and the waste or off-cuts can even be used as a fertiliser!”
The Building Regulations part AThe Approved documents, (England) part A, deals with building structures covers the structure of a building. This Approved Document goes into a lot of detail for traditional masonry buildings but almost none for timber frame, steel frame, earth building SIPs etc. For these you will need to consult a structural engineer (while SIPs structures are usually handled by the manufacturer)
With most forms of construction there will be implications concerning fire safety. These are covered in the Building Regulations and you can see examples of how to conform with these in Part B (Fire Safety)
Resistance to the passage of sound
The degree of sound insulation required within and between houses and flats is covered in Part EThe Approved documents, (England) part E, deals with resistance to the passage of sound of the Approved Documents.