residental building on foundation slab - 0,80 m above terrain? 1

[greznik91]

Residental building (masonry walls and RC slabs with timber roof), has to be 0,80 m above terrain - due to the possibility of floods.

This is what I have had in mind:

This is what the contractor suggested:

I know what the contractor suggested is cheaper but I feel this is completely wrong. What would you suggest/do in this situation?

 

[phamENG]

If flooding is the concern the contractor's idea has the potential for catastrophic consequences. It's gravel, so it won't be as susceptible to erosion/scour, but I think the risk is still there - especially if your flood velocities are fairly high. Your idea is the way it's done in my area - though we have spread footings under our foundation walls.

 

[SlideRuleEra]

What would you suggest/do in this situation?

1) Reject the Contractor's proposal.

2) Design the foundation in accordance with FEMA P-550 "Recommended Residential Construction For Coastal Areas".
The project may not be in a coastal area, but a flood-resistant coastal solution may be appropriate.

http://www.SlideRuleEra.net

 

[n3jc]

I agree with both replies. But would you still construct the stem walls in case the foundation slab in 'only' 300 mm above terrain?
Would you do this in case flooding is not an issue?
As I know, you have to make stem walls everytime foundation slab is above ground level?

 

[phamENG]

Yes, I would still extend the stem wall down. Without it, the building's lateral resistance is limited by slab-to-backfill friction. Wind would be bad enough, but if there's any chance of seismic activity I'd say the no foundation wall wouldn't be acceptable at all. It wouldn't be any stronger than a typical backyard shed. Not my idea of a safe and secure house. Then there's frost heave (level of concern varies by locality).