Good morning,
Interior installation of 3/4″ Thin Brick veneer over plywood and extruded metal lath using Modified Thin-set.
Should I use a Scratch Coat or just back-butter, press firmly and give a little wiggle?
Thanks
Listeners write in about removing masonry chimneys and ask about blocked ridge vents, deal-breakers with fixer-uppers, and flashing ledgers that are spaced from the wall.
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.
Start Free Trial NowGet instant access to the latest developments in green building, research, and reports from the field.
Start Free Trial Now
Replies
Expanded Metal Lath
2 Hours of sleep Tthhhpppp!!
Never done that, but in the days before cement board used expanded metal under tile. There I skimmed the wire with thinset first and let that set before spreading the coat for setting the tile. Didn't scratch it, though.
Why metal lathe instead of cement bd?
Not sure, but I think metal lath would dictate the scratch coat ... but I'm not a tiling expert.
Doesn't the lath make it hard to scratch?
A 'scratch' coat I think is simply a rough base coat ... not troweled smooth. Maybe w/ like stucco they used to intentionally 'rough it up' a bit. You don't really "scratch" it per se' I don't think.
The origin of the term "scratch coat" comes from the fact that, when plastering, the plasterer would actually scratch it with a sort of comb.
anything to give it tooth for the next coat.
Plaster on lathe is
Scratch
Brown
Finish veneer
Lathje dictates a fill coat that could be called scratch, but he is making his work harder by using scratch and lather instead of just using cement bd
Thin Brick Substrate
Whether interior or exterior, a substrate consisting of cement board, waterproof joints and thin set is typically quicker, less expensive and can provide a long term warranty. When consulting with architects and builders, we do not recommend metal lath/scratch coat systems for thin brick or stone.