One of the most important and successful methods of preventing the flooding of a structure is to raise the elevation, higher than the possible flooding waters. This is the most obvious technique for preventing flooding of any structure. If the structure is raised higher than the water will rise, then the possibility of flooding is removed.
Although the raising of your home is a method that most individuals would consider a last resort, the insurance companies as well as building codes are starting to insist on this method of flood control and protection. There have been thousands of homes, throughout the country, that have been raised to accommodate the new building codes, and to allow the issuance of a reasonable rate, for the insurance of the structure.
The height of the structure is determined by the distance the structure is located from the flood plain. Each area has different restrictions as well as elevations. FEMA, the Federal Emergency Management Agency will determine the elevation as well as the specifics required to comply with the local regulations. In some areas that are prone to flood waters as well as the surf pounding beneath the structure, special requirements are specified to allow the water to flow under the structure without structural deterioration of the foundation. Again, FEMA is the agency that will determine the specific requirements for this type of construction.
What is involved with the raising of a structure?
1.) Evaluation of the structural integrity of the structure. It is imperative that the structural components of the structure are reviewed and evaluated by a structural engineer. This evaluation must include an inspection of the existing structure of the building, as well as additional structural supports that will be required to properly raise the structure. All buildings are different in their specific requirements for structural support. An engineer that is experienced with raising structures to the proper elevations must be involved in determining the details of the supports required to lift the building without damaging the structure.
2.) Dependent upon the type of structure involved, the design of the structural members necessary to properly and safely raise the structure must be determined by a combination of the structural engineer involved as well as the company contracted to raise the structure. As I have indicated in several different discussions within this website, research on the internet must be accomplished to determine the best local contractor for the actual raising of the structure. The experience and reputation of the contractor involved with the raising of the structure is an important decision. In many instances the recommendation of the local structural engineer that has evaluated the structure should be used to make the choice for the lifting contractor. In the Northeast area, there are only a handful of reputable contractors capable of properly lifting the structures along the shoreline in the Northeast.
3.) Once the contractor that will perform the lifting is selected, the type of structure and the environment around the structure is evaluated. In all instances, the perimeter of the structure must be accessible for easy access by the lifting contractor. Foundation walls must be exposed to allow openings to be cut into the perimeter foundation walls for all lifting assemblies. The lifting contractor, once the foundations around the structure are exposed, will open the foundation as required to accommodate their equipment necessary to perform the lifting.
4.) In most cases, long sections of wide flange beams are inserted through the foundation walls in structurally dimensioned and designed places. These beams are positioned according to the structural assembly of the structure that is being lifted. Again, the interaction of the structural engineer and the lifting contractor is a necessary to ensure that the structure is properly supported during the lifting operation.
5.) The lifting contractor has now placed the long beams that will be used to accommodate the lifting of the structure. Once these beams are in place, the proper supports for the lifting jacks and internal supports for the structure will be evaluated. There must be proper concrete footings or mats installed to allow the support of the lifting jacks, as well as the temporary supports, that will hold the structure at the elevated height while the final foundations are constructed. These bearing pads are usually poured in place concrete mats that have been designed to properly support the individual point loads of the jacks as well as the temporary supports.
6.) Once the lifting apparatus is in place, as well as the placement of the supportive foundations, the jacks are assembled as designed by the structural engineer in conjunction with the lifting contractor. These jacks, are normally hydraulic jacks, that are connected by hydraulic hoses to a common manifold to allow the coordination of the lift to be properly managed by the lifting contractor. In some smaller lifting projects, these jacks are manually operated by individuals that monitor the lifting of the structure.
7.) There will be no lifting of the structure until all existing components of the structure are evaluated and freed from any existing foundations, supports, columns or beams. The structure must be totally free from all existing foundation elements to allow a clear and unobstructed lift.
8.) In addition to the assurance that all existing connections have been severed from the existing structure, all utilities that provided service to the structure, must also be removed from the existing structure. In many cases, the electrical power is disconnected or lengthened to allow the power to remain intact as the structure is raised. However, all rigid piping such as water, sanitary and gas lines must be disconnected from the structure prior to lifting. Although this sounds like common sense, there are several instances where a pipe or a line was either forgotten or not identified and caused difficulties as the structure was lifted.
9.) Interior walls, roof, or other structures within the building should be structurally evaluated for additional support. In some instances, there might be supporting walls that will require additional bracing to ensure their structural integrity, while the structure is being lifted to the elevated heights. These supports must be in-place prior to the actual lifting of the building.
10.) Now that all the supports are in place and the utilities have been disconnected, the actual lifting of the structure will begin. The lifting jacks must be coordinated and properly managed to guarantee that the structure is raised evenly, and the lift is made with the minimum of damage, twisting, or shock to the existing structure. Slow and deliberate is the method for proper lifting, and once again the importance of making the proper selection of a lifting sub is obvious.
11.) The lift occurs slowly and is monitored as the structure is raised. Any structural issues resulting from the slow lift will be identified and corrected as the lift occurs. Again, this is the reason why, you should only select a contractor that is experienced in this type of structural lifting. I emphasize that the lift is completed very slowly to minimize any damage as a result of the forces exerted on the existing structure during the lift.
12.) Once the structure is at the required design elevation, the lift is stopped. In many cases, the actual elevations achieved will be slightly higher than the required elevations, to assure compliance with all the regulations. Upon achievement of the required elevation, the long beams are temporarily supported with timbers, blocking, masonry block, or whatever structural, temporary element that the individual lifting contractor may decide to use. The installation of several temporary supports will reduce the overall pressure exerted on each individual support structure. The more temporary supports the less each one has to withstand. The placement of these individual temporary supports must be coordinated with the overall final foundation plan of the structure. The temporary supports should be placed in locations that do not interfere with the permanent supports. In many instances of structural lifting, the permanent supports consist of individual columns that are constructed of poured in place concrete, masonry blocks, structural steel, or even heavy wood columns. The permanent supports will be constructed under the elevated structure. Obviously care is taken when any work is performed under an elevated structure, all safety precautions such as secondary supports must be in place.
13.) After the structure has been lifted to the proper elevation and the new supports completed, the dropping of the structure down on the new supports will be done. This is all performed by the lifting contractor that has been contracted to provide the lifting of the structure. Once the structure is dropped down onto the permanent supports, all temporary supports are removed from under the lifted structure. A structural evaluation of the structure being supported by the permanent, new foundations, is performed at this time to once again ensure that the structure is behaving as engineered.
14.) After the setting of the structure down on the permanent supports has been completed, the structure is attached to the permanent supports with either clamps, straps, inserts, anchor bolts or other means of permanently and structurally attaching the structure to the permanent support foundation. This is required by code, to provide uplift resistance caused by wind. In most cases the lifting contractor will provide the proper attachments to ensure that the structure has been properly tied down.
15.) The re-establishment of all utilities as well as the re-grading of the perimeter of the structure will be necessary to complete the lifting operation. In most cases, additional work is performed on the home to further the renovation aside from the lifting. Many times, the expenditure of money to lift the home is only a portion of the money being spent to totally renovate the existing home in terms of siding, roofing, etc. If the owner of the home feels that the lifting expense is a justifiable expense, then a renovation of the lifted structure normally follows.
These ( 15 ) steps, summarize in a very simple fashion, the steps that will be involved with the lifting of a structure. Again, the proper research to find an experienced and reputable contractor to perform the lifting is strongly advised. In many instances, the hiring of a separate general contractor to perform the entire operation of lifting the home, reinstalling all the utilities and probably renovating the lifted home is also an option. In this case the selection of the proper lifting contractor can be assigned to the general contractor.
In real estate , the most important characteristic of any structure is, location, location , location. If the structure is in a location that is meaningful, exceptionally beautiful, immediately on the waterfront, or uniquely located within any type of possible flooding situation, then the lifting of the structure might be easily justifiable. The lifting of structures is occurring more and more, the techniques are evolving and have become more efficient and professional.
Don’t be intimidated by the thought of lifting your structure out of harm’s way! Research the internet, and select the proper contractor, with the proper experience, that will result in a structure that is both resistant to flood waters and safely elevated to the proper elevations.