Is my floor strong enough for 12x12 ceramic
Schluter says Ditra XL will work over 3/4" ply on joists that are up to 24" o.c. I have to take their word for it since they have tested it and I trust what they say. Just remember though, those are minimum recommendations and the span between the joists should still meet the L360 maximum deflection criteria.
Then you have the trusses' deflection rating. Have you contacted the manufacturer to see what their rating is at 50/20 live load/dead load? Minimum code is L360 at 40/10 for regular flooring, so I would like to surpass that when switching to ceramic or porcelain tile.
Tile 4 You LLC Troy, MI
KERDI Shower Specialist ... DITRA Installs ... Product-Method suitability consultation. I have NEVER made a mistake, I thought I did once...........but I was wrong! - PRODUCTS ADVERTISED WITHIN MY POST ARE NOT ENDORSED BY ME!