10-6cm outer wall panel; 20-8cm insulation layer;
30- Double skin wall cast-in-place layer; 40-6cm inner wall laminated board;
50- FRP connectors (accessories) for exterior walls; 60- Pull bolt (accessory).
The Direct Cost Increase of Using Double Skin Wall Sandwich for Exterior Walls
The cost for a 6cm outer wall is ¥2,750/m³; the 8cm insulation layer, including accessories, costs ¥2,250/m³; and the 6cm inner wall laminated board processing fee is ¥1,950/m³. These prices include shipping and installation fees of ¥250/m³, as well as reasonable profits accounted for by the Shenyang Component Factory.
The processing fee for the 6cm inner wall composite panels is comparable to traditional cast-in-place aluminum formwork, priced at ¥117/㎡. This is ¥67/㎡ more expensive than traditional aluminum formwork. However, since the inner wall composite panels cover roughly 65% of the outer wall panel area, the resulting cost increase is approximately ¥44/㎡ based on the outer wall panel area.
The shear wall section of the double skin wall sandwich exterior wall causes an increase in steel reinforcement by no more than 5%, adding an extra ¥9/㎡ to the cost.
In total, the costs break down as follows: outer wall ¥165/㎡, insulation layer ¥180/㎡, plus ¥44/㎡ for inner wall composite panels and ¥9/㎡ for additional reinforcement. This sums up to a total cost increase of ¥398/㎡.
Cost Reduction Analysis for Prefabricated Housing Using Double Skin Wall Sandwich Exterior Walls
By adopting this system, savings are realized in external wall formwork costs at ¥50/㎡ and external scaffolding costs at ¥40/㎡. When calculated based on 75% of the external enclosure wall area, this equates to ¥53/㎡, resulting in a total cost reduction of ¥103/㎡.
Ultimately, utilizing the sandwich exterior wall system results in a net increase of ¥295/㎡ in exterior wall system costs. However, since the double skin wall sandwich exterior wall includes built-in insulation, it eliminates the need for half-hour fire-resistant windows.
The cost of half-hour fire-resistant windows adds ¥300/㎡. Calculated over 75% of the external enclosure wall area, this translates to an additional ¥100/㎡. By omitting these windows, the exterior wall cost effectively decreases by ¥100/㎡.
Therefore, after accounting for this saving, the net cost increase is ¥195/㎡ (295 – 100 = 195). This figure differs from the traditional EPS thin plastering system, where the price difference for fire barriers defines the final cost increase of the double skin wall sandwich exterior wall.
The lowest market price for the thin plastering system is ¥85/㎡, meaning that using the double skin wall sandwich exterior wall costs only ¥110/㎡ more than the traditional cast-in-place and thin plastering exterior wall insulation system. This difference is roughly equivalent to an additional building area cost of just ¥55/㎡.
Considering that the service life of double skin sandwich exterior walls is more than twice that of thin plaster exterior wall insulation systems, the two options are now comparable in value.
Must log in before commenting!
Sign Up