Laths & Lime Plasters
Laths are used on timber framed, studwork and on structures of uneven surfaces to bring them into a oneness ready for the application of lime plaster. Laths are either riven (split) or sawn. Riven laths are stronger than sawn but because they are split by hand, they are a lot more expensive, therefore people tend to use sawn. Laths tend to be between 25-32mm in width and 6-8mm thick. You can purchase laths in soft and hardwood. When applying the plaster to the laths it has to be moist enough so that you can push the plaster through the gaps, to create the perfect key.
Laths are fixed parallel to each other, but need to be staggered every 8-10 laths so there is no shearing point, laths should be fixed between 6-8mm apart. Fixings can be stainless steel ring shank nails, coated screws or galvanised staples. However you should always take into account that the fixings are not only holding up the lath, but also the plaster that is applied to the lath. Caution must be taken when hammering nails in because this can cause a shockwave which could do potential damage elsewhere in the building. When covering beams or a flat surface with laths you will need to counter lath to leave a gap for the plaster to wrap around the lath to give a mechanical key.