Building Homes or Extensions/Roof slab


Sir....I am about to build a roof slab for a residential type building. The maximum room size is around 12' X 16'. It has been planned to go for 8mm dia Fe500 reinforcement @ 150mm spacing both ways. In addition the extra top at supports also shall be 150mm spacing with 8mm dia reinforcement.

Please advise whether the reinforcement would be sufficient



Hi Geoffrey, based on your information and depending on the slab thickness it sounds like you  should be fine..the 8 mm seemed a little small but when you factor in the tight spacing and the added top steel over the supports I can't see anything wrong with this design.  Plus you are using the higher tensile strength grade fe500.. I am not an engineer however, my response is based on my 40 + years in the industry.  Sincerely Bruce Johnson  

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Bruce E. Johnson


I can answer any construction related question in regards to carpentry, concrete, drywall, masonry, structural elements of any type of building, residential or commercial. Interior or exterior.


Custom Commercial and residential buildings. Churches, theaters, schools and auditoriums. Most recently I am working with the Catholic Church on several design build committees. I have a website related to scheduling and project supervision. Although my expertise is more related to multimillion dollar commercial, educational and theatrical projects my generous credentials in residential and remodelling construction make me a viable source of information regarding all forms of building questions.

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