Lath and Plaster
Riven oak, chestnut or larch laths nailed with a gap, then three coats of lime plaster gauged with animal hair. The plaster squeezes through the gaps and forms keys that hold the ceiling up.
Carbon and evidence
How This Is Made
An Environmental Product Declaration is issued by a manufacturer against a declared unit. This record has neither, so it states sourced facts about process and provenance instead of a carbon figure.
The standard British internal ceiling and partition finish until plasterboard displaced it
Process
Feedstock
Mineral
Lime and sand gauged with animal hair, on riven oak, chestnut or larch lath
Process heat
Calcined
The lime is calcined at roughly 900 C and recarbonates as it cures and afterwards. Both are stated; neither is netted against the other, and no figure is held.
Binder
Lime
Fabrication
Site-formed
Sourcing: national; lath is supplied by specialist merchants
Who Builds It
Specialist trade
Limited UK availability
Three coats with curing time between each — weeks, not days. Sequencing against other finishes is the practical difficulty
End Of Life
Separable
Plaster and lath separate cleanly; the lath is compostable and the plaster is inert rubble
Maintenance: Patched in lime by the same trade; failed keys are re-secured from above rather than replaced wholesale
Specification Risk
What a specifier has to resolve before this can be built.
- Certification
- No Agrement for the buildup; the bagged lime and the lath carry their own supplier data
- Fire
- The plaster is non-combustible; the lath is not, and no fire rating is held for the assembly
- Warranty
- Plasterer workmanship warranty; material suppliers warrant their own materials only
- Insurance
- Not normally an issue
- Supply
- Riven lath is available from specialist merchants; plasterers who work in lime are the constraint
Read This Honestly
- •Lime is calcined at high temperature. Being a traditional finish carries no carbon advantage, and none is claimed.
- •The bagged lime may itself hold an EPD. That would cover the manufactured material, never the applied ceiling, which is what is specified.
- •Not a like-for-like substitute for plasterboard on programme or cost — it is materially slower.
Design & Specification Notes
Riven oak, chestnut or larch laths nailed with a gap, then three coats of lime plaster gauged with animal hair.
Material Note
The ceiling is the buildup, not the bag. Lath spacing, hair content and the timing between coats decide whether the keys form, and the keys are the entire structural principle.
Typical Uses
- •Interior ceilings
- •Acoustic control
- •Service zones
Key Performance
Confirm acoustic, fire, humidity and demountability performance for the selected ceiling system.
Specification Actions
- •Confirm the lath species and whether it is riven or sawn — riven laths key better and are what conservation work normally requires.
- •Confirm the hair content and coat sequence, and allow each coat to cure before the next; rushing the sequence is what cracks it.
- •Record it as separable — the plaster is broken off and the lath composts, with no bonded composite to landfill.
Indicative Health & Indoor Air
Lime, sand, animal hair and timber. Vapour-open. Wet lime is caustic during application — a control for the plasterer, not the occupant.
Products in this category
6 products from 5 manufacturers · 12 in this category. Ordered by the evidence each record holds, never by commercial standing.
Specification
- Finish
- Haired lime plaster on riven lath
- Service life
- 100 years