[[image:IMAG1842-2 Lath ceiling.jpg|right|250px|Laths before plastering]]
'''Lath & plaster''' walls & ceilings are often found in old houses. They c onsist of 2 parts: # Laths, thin [[wood]] strips [[nail]]ed to the joists or uprights, with ga ps between them # [[Plaster]], pressed on so it squeezes through the gaps and grips the lat hs
Historic L&P ceilings use wood laths & lime plaster. Modern L&P is seen occ asionally, typically with galvanised metal EML and gypsum plaster.
==Properties=Old L&P ceilings contain much more plaster than plasterboard, giving much b etter [[noise]] blocking. The thicker plaster also improves [[fire]] resist ance some.
Historic L&P is often in poor condition. If a lump drops down it can cause cuts requiring hospital cleanup and [[Adhesive|gluing]] or stitching.
==Repair=Where its wished to retain an L&P ceiling that's beginning to break, [[scre ws]] & penny washers can be placed into joists to hold pieces up. Don't att empt to screw into lath, its a futile exercise. Pouring diluted [[PVA]] or fresh plaster onto the topside of the ceiling is done sometimes to stabilis e old ceilings. Missing patches are fairly straightforward to [[Fill|patch] ] with plaster. Once stabilised, a damaged ceiling can be skimmed, or in so me cases patch filled.
==Removal=When L&P begins to collapse its usually removed. Though simple to do (whack it), the normal result is filth so severe that it ruins the finish on ever ything it touches. Once gone, either the numerous nails are removed & new p lasterboard is applied, or loose laths are refixed and the whole wet plaste red.
Replacing L&P with plasterboard significantly increases sound transmission from room to room.
==Overboarding=Putting plasterboard over (or technically under) old L&P is another repair option. The sound retaining property of L&P is retained, and the filth from hell is avoided. But locating joists for the new screws can be rather hit & miss. If you can lift a few floorboards above, drilling some tiny marker holes next to joists can be a real help; joist positions can then be pencil led onto the ceiling or the top of the [[wall]]s.
[[Category:Basics]] [[Category:Noise]] [[Category:Period Property]] [[Category:Plastering]] [[Category:Repair]] [[Category:Walls]]