The Slab Decision: Difference between revisions
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We are excited about [[Helical Pier Foundations]]. However, for the purpose of [[Seed Home 2]] - the slab has a distinct labor advantage in rollout - Phase 1. Here's why: | We are excited about [[Helical Pier Foundations]]. However, for the purpose of [[Seed Home 2]] - the slab has a distinct labor advantage in rollout - Phase 1. Here's why: | ||
#Overall house cost is comparable. | #'''Overall house cost is comparable.''' A slab appears to be more expensive by itelf(estimated $10/sf based on $8k avarege + $1k gravel + $1k excavation) see [[Concrete Slab]]. | ||
#'''Owner-builder labor is reduced significantly.''' In our model, a foundation is outsourced (beyond the scope of a novice owner-builder) - whether helical pier or concrete slab. In the slab case - the labor savings is the floor. In the helical pier case - a framed floor module with 3/4" plywood is no longer needed! That is 1-2 days of work saved. | |||
#Our Seed Home 2 budget has $1611 for floor, and $1500 for foundation (per 256 sf). This is a total budget of $12444 for 1000 sf for the floor + foundation. We are likely to get a concrete slab foundation for $10k, and the other $2k can go for floor finish (polished concrete, vinyl, carpet). | |||
#Unknown - for expandability upwards, we require 8000 lb per pier. This indicates higher pier foundation costs, as a 3-helix 10' [[P2 Pier]] cannot hold 8000 lb - it needs an extension with additional 2-3 helices - in 1500 psi clay soil. This would be fine in stronger soils, but we're trying for a more robust solution. | |||
Latest revision as of 17:40, 21 September 2020
We are excited about Helical Pier Foundations. However, for the purpose of Seed Home 2 - the slab has a distinct labor advantage in rollout - Phase 1. Here's why:
- Overall house cost is comparable. A slab appears to be more expensive by itelf(estimated $10/sf based on $8k avarege + $1k gravel + $1k excavation) see Concrete Slab.
- Owner-builder labor is reduced significantly. In our model, a foundation is outsourced (beyond the scope of a novice owner-builder) - whether helical pier or concrete slab. In the slab case - the labor savings is the floor. In the helical pier case - a framed floor module with 3/4" plywood is no longer needed! That is 1-2 days of work saved.
- Our Seed Home 2 budget has $1611 for floor, and $1500 for foundation (per 256 sf). This is a total budget of $12444 for 1000 sf for the floor + foundation. We are likely to get a concrete slab foundation for $10k, and the other $2k can go for floor finish (polished concrete, vinyl, carpet).
- Unknown - for expandability upwards, we require 8000 lb per pier. This indicates higher pier foundation costs, as a 3-helix 10' P2 Pier cannot hold 8000 lb - it needs an extension with additional 2-3 helices - in 1500 psi clay soil. This would be fine in stronger soils, but we're trying for a more robust solution.