Category: Foundations

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This vicious thunderstorm has approximated damages in the billions and claimed 17 lives. In and about Punta Gorda, trailers lay toppled or blown aside. Shards of metal and wood lay scattered on lawns.

It could have been much worse if it weren’t for the residential building code changes which were instituted after Hurricane Andrew in 1992, as awful as this loss is. Andrew, the most harmful U.S. storm on report, blasted its way across south California, creating 24 departures and $26.5 million in damage -mainly thanks to high winds.

The magnitude of harm due to Storm Andrew was unprecedented in the United States. Prior to it, there had been a 25-year lull in essential storm activity over the Atlantic and Gulf coasts, and building codes are not sufficient to restrict the lack of life and property experienced in Hurricane Tim.

Today, rules therefore are being more rigorously applied and have already been reinforced.

“Due to Storm Tim and additional storms in this region, the home building codes are becoming considerably more specific in Fl,” stated Dennis Graber, expert engineer and director of technical publications at the National Concrete Masonry Association. “By conforming to these codes, houses were better able to defy the onslaught of Hurricane Charley.” The National Hurricane Center records that constructing codes reflect the lessons experts have learned from past disasters and indicate that homeowners in hurricane areas contact local building code authorities to find out which requirements are necessary for home improvement jobs.

Construction is encouraged by the Federal Emergency Management Agency with strong, influence-resistant materials, for example tangible brickwork, within homes and other structures located in hurricane-prone places.

Keeping it high and dry is the most important design goal for a foundation. Afterward, you’re prepared to address water and wind loads structure and soil.

Select the Foundation Sort

Foundations for Flood Zones:
Foundation Type: A Zones – Coastal A Zones – V Zones
Monolithic Slab on Grade: S4 – P – P
Stem wall/Crawlspace/Solid Foundation Walls: S1 – P – P
Pier: A – S3 – S3
Pile: A – A – A

Legend: A=Approved, P=Prohibited or not recommended, S=Satisfactory

Open foundations (pier or pile) should be used in V or Coastal A zones. Base wall, crawlspace, stem wall, and slab-on-grade are Normally prohibited in V zones.

Construct a Hurricane-Resistant Foundation

1. Stem walls should just be installed in A zones with limited wave actions or flooding-operable base ports near the bottom of the wall to let passage of flood waters. Stable base walls aren’t advocated in A zones with substantial hydrostatic or hydrodynamic forces.
2. In A zones with potential of erosion/ waves or scour, and in V zones with erodible soil, pier foundations aren’t advocated.
3. Slab-on-grade foundations shouldn’t be installed in any place subject to scouring.
While there are Many foundation types, not all are suited to coastal regions.

Elevate Habitable Spaces and Critical Services Above DFE

To realize greater disaster resistance of flood levels that may exceed the DFE, stipulate a 2-foot clearance, or “freeboard” between the site DFE (or BFE if no DFE is identified) and the bottom of the lowest horizontal framing member. Elevate service and utility apparatus above the DFE and, in coastal regions, situate them on the landward side of the, piers, or piles.
Situate as follows:
• Electric: Find find, and buried lines below anticipated scour degree. Run exterior lights off movement detectors in order to avoid electric components.
• Plumbing: When possible, and secure AC or heat pump equipment to resist winds and
• HVAC: Run pipes and drains between joists when possible. Locate ducts within conditioned space.
• Fuel storage: Elevate fuel tanks and anchor them satisfactorily

Withstand Flood Forces

Once the type of foundation has been selected and its altitude place above the DFE, some precautions in V flooding zones and Coastal A are crucial to address Forces due to moving water from storm surge or wave action on the basis:
• Leave licensed professionals footing and pile layouts
anticipated storm surge.
• Define corrosion-resistant hardware, (hot-dipped galvanized or stainless

Within all flood zones, open foundations with little or no impediments or enclosures below the BFE are recommended. When building enclosures, observe the following:
• “V” garage doors and zone enclosure walls must be of breakaway building.
• A breakaway wall should not be overlapped by siding.

If building a strong foundation wall or crawlspace base, establish the following:
• Comprise flooding openings for water pressure equalization on outside walls.
• Keep interior crawlspace level above the exterior level to eliminate ponding after a flood.

In flood-prone coastal areas, there exists consistently a statistical likelihood that thunderstorm surge or flood levels will climb above the BFE. To avert problems in any flood select materials which are resistant to mold and that dry readily such as Gypsum, and steel studs.

Wind Resistance

Unlike flooding loads any foundation system can be designed to withstand uplift and resist overturning due to wind forces. Where wind speeds are greater than 130 mph may be anticipated a licenced building services contractor will be required. At lower rates, foundations may be constructed according to the prescriptive standards.

In addition to the base, overturning and uplift functions plays a significant role in transferring wind loads from the rest of the home to the ground. It really is vital that you define exterior wall-to-foundation connections and floor-to-base connections. Strategies include using anchor bolts, strapping, tiedown hardware, wall support, and continuous sheathing. Code requirements change by building size, material, base kind, and design wind conditions (See SSTD 10 Section 303, WFCM Section 3.2, and COFS/PM Sections 5.2 and 6.2).