I want to know the thickness (slab) of roofs, which can be considered safe.
What if there is a roof 7 inch thick, on non pillared walls with no iron supports beams on walls, being reinforces with 7 inch more slab (cement, sand and very fine concrete).
So that total thickness comes to 14 inch, will it be risky?
14 inch…the weight itself would be way too much…one more thing never heard of 14 inch slab unless its a bunker
But what if its once done and is intact and dry now?
so will it be safe after months , i mean no more wt issues , as wt will be distributed in all sides,
if you can understand ,what i mean
If the wt is evenly distributed than it should b ok
14 inches are too much its a wastage of money and if not properly reinforced slab will deflect due to own weight. For smaller spans 5 inch of RCC and 3 inch of floor finish is enough.
RCC slab of roof should be 9 inch…with 4 inch floor, plaster on ceiling side, etc total finished roof may be 13.5 inch…
Thickness of roof slab depends on alot of factors but mainly span....
In residential construction it is generally kept from 4 to 5 inches...
I think 14 inch roof is good for construction and safety measures.
Well i will wish an answer from civil or structure engineer,
or
any reputable construction company ,if they have the clues, and predictable out comes of the slab,,
It definitely depends upon the span of the slab... Normally 5-6 inch thick slab (without any finishes) should be alright for 12 ft to 16 ft span. But if the span increases, the slab depth also increases.
(A civil engineer)
But FS sb , isn’t it so that steel rebar quantity should also increase along with thickness?
@FS
sir,it means if finish wt[marble 2 inch(stone plus cement and sand)is added=7-8 inch slab so it should be OK?
my question remains ,what if there is no initial deflection ,so what are the effect after dried slab 10=14 thick,
will the dried wt equally distributed be a concern ??if so whats the solution ??the span is supposed 12 into 16 feet,and there are no pillars in the building,
@ B R Malik...
Yes the quantity of steel will change as the depth changes.
@ Dk
I could'nt understand 10=14 inch thick.
However initially the slab depth is suggested based on defection criteria. Later a PROPER REINFORCEMENT design is made which include all the WEIGHTS supposed to be on the slab during its service life (including any dead and live loads).
If the loads on the slab are too much, we may even have to increase the slab depth.
I mean between 10 to 14 inch,
my queries are for roof slab,
please slab depth is technical word, simplify it ,
@ Dk
By "depth" I mean "thickness".
Normally during design stage, we put some safety factors to include any accidental loads on the slab. However such an increase in the loads should properly be Re-designed.
If it is an existing building, previous design details and probably a visit to the site will be needed.
So does it(increased slab depth) increase the dead weight of structure ,and possibly damage to structure in stressful events[earth quake]?
Normally with a wider span without pillars more steel is added so it can hold and bear the pressure…by making it 10 or 14 inch thick you would most likely need 1 inch steel to just bear the weight… Plus more the weight the more accuracy will be required to distribute the weight on the walls…
@H-T good points
More thickness of slab means more dead weight of slab (BTW the concrete self weight is quite a lot). More steel will be needed in that case. Our approach is to use minimum thickness of slab, as it is more economical.
Why you want to put extra weight on the slab than needed?