Just today I was exposed to a client that had some H2O issues on the interior of their structure. Further investigation revealed that this is a lathe & plaster installation (appx 1926). The puzzling part is the backing behind the lathe strips. It appears to be some sort of fibrous material, possibly ‘horse hair’ as an insulating material.
Client would like these materials removed/replaced. Interior shows many damaged areas, especially around windows, and would like to restore
Any thoughts or suggestions are appreciated.
Job located in south FLA, near Lake Okeechobee. Read high humidity most of the year.
Replies
I assume you aren't merely referring to the hair in the scratch coat. The scratch coat in the plaster - that forms the keys that lock into the lathe - often has fibres (horse hair) added to the mix to improve its structure. If it's not that, you might want to include a picture.
Are you reparing the plaster in just the damaged areas, or replacing all of it? Walls and ceiling? I live in central FL and there are plenty of lathe and plaster homes around (I live in one), but I don't think I ever saw the material you speak of behind the lathe.
I've worked on jobs like this, although I'm not sure exactly what you're going to do. I'm pretty sure you'll find black mold and rotted framing along the way.
If you're replacing sections of the plaster, I've found 1/2 Hardibacker works very well (shimmed flush with the existing wall, of course). I fill the joint ( <1/4" ) between the hardibacker and plaster with construction adhesive, prime, then finish off the joints with mesh and mud. I've had no problems with stress cracks using this method. If you have any problems matching the texture you could just give the whole place a nice knockdown and be done with it.
Edited 3/17/2005 9:47 pm ET by bbqjason
Traditionally the first, scratch, coat of plaster in a plaster-lath job had horse hair stirred into the sand plaster mix as reinforcement. Given it is still working almost eighty years later is testimony enough as to the wisdom in its use. Not sure 'modern' alternatives would hold up any better.
If the fibrous material is actually filling the stud bays you may be seeing Spanish moss stuffed in as low cost insulation. I have never seen it in this situation, mostly old Florida homes were built without any real insulation but I have read that it was done. I guess if the builder had access to large quantities of horse or hog hair they might have used it as insulation. Once saw newspapers, crumpled but not shredded like modern cellulose, laid in the attic for insulation.
I think its a fire hazard as both Spanish moss, once it dries out, and hair will burn fiercely but back in the 30s people used whatever was cheap and handy. Spanish moss was sometimes dipped in rubber to create an early version of foam rubber. Mattresses and cushions were manufactured in Florida for years using this method. It made a nice cushion. Firemen sometimes call modern foam rubber solid gasoline but it is tame, safe and fire resistant compared to rubber coated Spanish moss. This stuff was outlawed when it was found that a lit cigarette that fell on it would easily ignite it.