Good PM PHMers... i want to help out a friend who has an issue with their current flooring. (ill attach pictures soon, but im sure you'll get the idea). THey'll be moving in to a lowcost residential unit with the second floor having steel rectangular tubes i suppose for support and covered with plywood as the top floor. second floor is approximately just 20sq meters. Now they prefer to have a concrete floor slab instead of this. Can we somehow fill the hollow spaces in between the steel supports with concrete and maybe 10mm rebars(welded to steel)? I am not sure if the structural integrity of the floor would be comprised or be strengthened by this approach. your opinion is highly appreciated. thank you 🙂
, as other PHM members has recommended, for any changes to the structure of an existing bldg/house, it would be best to advice your friend (bring along the house plan) to consult a structural engineer of your design proposal. it is the most responsible way of doing things to ensure that the safety issues of the structure will be looked at ... even if we have a PHM member here that is a structural engineer, it would be difficult for him/her to provide a comment on a critical aspect without reviewing the house plan in detail ... the cost for the consultation is worth it - peace of mind knowing that the plan is safe for the persons using the house ... cheers
Boo!
In a residential low cost housing the structure is not designed to carry a 2nd floor concrete slab. Kaya ang ginagamit nila ay rectangular tubes and plywood flooring. A 20 sq.m concrete slab with thickness of 0.1m (4") will weigh around 4,400kg. Imagining a 4,400kg concrete without a proper support. To be safe the 20 sq.m. concrete slab need to have a columns and footings. It's the job of the structural/civil engr to specified what's the sizes of columns/footing, beams and reinforcement bars ang gagamitin.
My engineer charges me P2000 for a 1-2 hrs site visit/consultation. Pag kailangan ng technical details ng drawing I just ask him to draw "on the spot" sa bond paper and let him sign it.
andthank you very much for your input. Now i know why some low cost residential housing project settle for steel framed floors.. the existing columns and beams might not be able to support a conventional slab. On another note - do you have any rough estimate for the cost of a 4", 2nd floor slab (not a slab on grade.fill) per square meter? Im certain boo and the rest of the PHMers have already provided data for CHB wall costing, cant seem to find for concrete slab 🙂 thank you very much!
Prepare a budget at least 100K.
The scope of works are the ff:
1. Excavation/Backfilling
2. Concreting of footing & columns
3. Steel Works (reinforment bars)
4. Formworks
5. Concreting of 2nd Floor Slab
6. CHB Laying
7. Plastering/finishing
8. Electrical Works
9. Painting works
below was my estimate for a concrete slab with an area of 10m (length) x 4.5m (width) x 150mm (depth) for our house construction. actual usage when i was monitoring the concrete pouring of one slab, it consumed 33 bags of cement to complete the slab ... you can easily get the ratio for a 20 sqm area from this 45 sqm area ... hope this info helps ... cheers
6.7500 = total volume in cubic meters
0.9643 = cement in cubic meters
1.9286 = sand in cubic meters
3.8571 = gravel in cubic meters
34.0489 = cement in bags
Boo!
thanksfor the detailed breakdown.. i can just assume for a 20sqm slab (for example) is 50% cheaper using your estimate for your 45sqm slab. How bout for the steel reinforcements? I know 2nd floor slabs have more members and reinforcements vs. ground slabs... do they cost as much (or more) as the cement+sand+ gravel materials also? thanks!
check out the concrete estimate i posted under building materials, i used 20 sqm slab as an example for the concrete computation.
as for the the 2/F slab reinforcements, your correct, there is more rebars on a 2/F slab compared to a ground slab. the breakdown i provided above is for a mezzanine slab which is why the thickness of the slab is 150mm. it's the same thickness for the 2/F and the roof slabs of our house ... cheers
Boo!
