Partial Perimeter RetrofitsRequire Attention to Detail
Anchor bolts & hold downs
May not need cripple wall
- PARTIAL PERIMETER RETROFITS REQUIRE MORE ATTENTION TO DETAIL
- Partial perimeter foundation system involves much more work
- Constructing a partial perimeter foundation system for a post and pier type house, involves much more work than installing new sheathing, foundation sill plate anchors, and miscellaneous framing anchors, which is typically all that is needed for houses with an existing continuous foundation and cripple walls.
- Before excavating
- Prior to beginning to excavate for the new concrete footings, a system of shoring must be installed to adequately support the house where some of the existing posts and piers must be removed.
- Proper shoring is not only a major safety concern but it also serves to prevent damage to existing interior and exterior finishes like plaster that are intolerant of even small changes in the level of the supporting floor.
- Preparing to pour the new concrete foundations involves accurately placing new anchor bolts and hold-downs as well as installing the needed reinforcing steel.
- The form work for the vertical stem wall must be strong enough to contain the concrete as its is poured and vibrated to form a solid mass without voids.
- If the optional masonry stem wall is used, proper knowledge of mixing and placing mortar are essential to its proper construction.
- Cripple Wall May Not Be Needed
- If the existing floor level is close enough to the ground, a cripple wall may not be needed on top of the new foundation wall
- In this case the top of the new foundation must be very carefully leveled before it is poured.
- Good carpentry skills
- All of the remaining work, including installing a new cripple wall if required, requires good carpentry skills to provide all of the additional nailed and bolted connections this system requires.
- BUILDING INSPECTION REQUIREMENTS
- The local building inspection authority will determine the exact number and types of inspections needed during the construction.
- Some jurisdictions may require a preconstruction inspection to determine if a prescriptive method is appropriate or if conditions exist that need the services of an architect or engineer.
- Typically inspections are performed prior to pouring any concrete or grouting of any masonry.
- In addition, a framing inspection will be needed during which the nailing of any cripple wall sheathing, the proper installation of plate washers on sill bolts and the installation of hold-downs and other connections will be verified.
- A final inspection may also be necessary to determine that exterior weather protective surfaces have been properly installed over the new cripple walls.
- SEISMIC RETROFITTING FLOOD-PRONE STRUCTURES
- Some elevated residential structures are located in both earthquake and flood hazard zones
- Seismic retrofit work must be compatible with standards for flood construction
- Part 59 of Title 44 of CFR
- FEMA’s National Flood Insurance Program
- Maps that show 100-year flood hazard areas
- Reviews maps before retrofitting