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A sealed, concrete vault roof should cost less than 20% of the total sq. ft. price -- low income and high end. If a low income unit in Mexico can be built for $30 sq ft (living area) the roof should cost less than $6. For a $125 sq ft construction in the USA the fancy, insulated roof should cost less than $25.These numbers are only a starting point. In the tropics, for example, the roof can cost almost half the total.
The biggest variable in roof cost is, of course, labor. A small pump rig in the USA at $400/day can do the work of 4 or 5 guys-- $400 translates to 12+ laborers at $30 / day (Mexican wages). So it is cheaper to build roofs in Mexico. If in Mexico, labor is aprox. half the cost of the roof, in the first world, it is about 2/3.
Approximate Vaulted Roof Costs(2005)
Cost (of roof only) per sq ft floor space * min max |
| BV, small (under 15 ft / 4.5M) |
$5 - $8 |
| Flat roof/floor system (not recommended) |
$6 - $10 |
| Small dome vault |
$7 - $10 |
| Large (6M, 20 ft) BV |
$7.50 - $10 |
| Sea shell shaped or other free form shape |
$8 - $12 |
| Large domes |
$10 - $15 |
| BV, Underground |
$15 - $25 |
| BV, high cieling (over 12 ft) |
$10 - $30 |
Assuming the walls are in place with vertical reinforced concrete columns, 10 ft on center. These prices include end and side beams (bond beams)
If you can do the vaults in sieres (units) you should be able to save 20%
TYPICAL ROOF COSTS (2005)
6" (15cm) thick 4X5m vaulted roof in Mexico (to cover 20 sq M / 216 sq ft of floor space) |
| USD |
| formwork--( reuse 4 times) |
$50.00 |
| 33 sq. M #66WW mesh |
30.00 |
| 33 sq M 26ga plaster lath-- thin, ungalvinized |
40.00 |
| 5.2 cubic m aggregate@$18/m--6" / 15cm, thick |
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| cement--(5/1 mix) 25 each 50kg bags X $8.50 |
215.00 |
| materials for polish |
40.00 |
| labor-- form work, pouring,and polishing, 4 guys X 4 days |
350.00 |
Total for Roof ( in Mexico) |
$875.00 |
Note: Cost per square meter, not finished on the inside is about $44/M or $4.05/sq ft
Note: These are all ball park prices and will vary greatly according to the site, labor cost and experience of the crew. These prices do not include horizontal bond beans.
Note: I'm assuming a power mixer and lifting buckets up to the roof with humans.The second roof in a series should be 20% faster. Second floor roofs can cost 30% more per sq ft
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