We're raising our house - anyone here with experience?

mary_in_scMarch 2, 2014

Three years ago we bought a 1200 sq. ft. ranch style house, built in 1968, on a barrier island. Our house is three blocks from the beach, and it's on a great lot and on a great street.

We currently rent it out as a vacation rental and visit it 5 or 6 times a year, but we're going to retire there next year.

From the time we bought it we planned on adding to it once we lived there full time, with the plan being to do most of the work ourselves.

But now we realize that we need to raise the house before we add onto it. First there is the cost of the flood insurance, which will be going up if the house isn't raised, and there is also the max flood insurance, which is $250k.

So -we're going to have it raised. I need to get survey to get an elevation certificate to determine how high it needs to be raised, but based on our next door neighbors house, which was built to the required height, it will probably need to be 8 feet off the ground.

Has anyone here had any experience with building a raised house, or with having one raised?

I've got so many questions that I'd like to get answered before beginning to try to find companies that do this.

I also have a lot of questions about building on piers. I'm used to houses on foundations, either with crawlspaces or basements. Designing and building those are pretty straight forward. But if you're building on piers, how do you figure out where you need the piers, and is the framing of the floor done differently?

So if anyone has any info at all I would really appreciate hearing about it.

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You need to search for reputable house mover/raisers. There ain't a whole lot of 'em, so you're not going to get much selection and you can bet they all know each other so I wouldn't expect too much vigorous competition either.

I would imagine you're going to have piles driven right next to the house then the house elevated, moved, and secured to the piles.

I am a licensed contractor in 2 states, have over 30 years construction experience, as does my wife, and we wouldn't dream of doing this ourselves. Don't even think about it.

    Bookmark   March 2, 2014 at 9:48PM
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Hi Trebruchet - Trust me - as crazy and often over confident in myself as I am, I know we can't raise the house ourselves. I feel really nervous about finding the right company to do it, and if there aren't many companies doing it then it may cost more than I was thinking it would. I guess researching and finding a reputable company is the first step to take after getting the elevation certificate so we know what height we'll need to be at.

We don't need pilings because we're not in a velocity zone so we cant stay with cinder block piers. I think we get the house raised (with jacks and I-beams) then have temporary cribbing placed under the house in various locations to support it, then probably have the existing piers dismantled (I think they're probably not up to snuff), then have new piers built to support the house and then the temporary cribbing removed.

The things that I don't know are:
are the mover/raisers also take on the work of putting in the temporary cribbing and/or the permanent piers or do I find masons myself to do that work. Or even if the raisers are willing to find/sub the pier work, should I find my own masons. And I even right that it is masons who do that work

Since we want to add on, I think the piers for the new additions should be done at the same time. So that means having plans complete, building permits issued, etc. We'll come up with the design ourselves - it's very straight forward) but we'll need an architect or draftsman to do the drawings. The drawings will have to show that wind-sheer building codes are met and I'm not confident we could get that right. But the main reason I don't think we can do that ourselves is that we know nothing about pier supported houses. Do architects design the pier support? Or is that done by a structural engineer?

And once the piers are in place and presumably inspected (I'm not sure what all has to be permitted/inspected where the house is, but I assume most things do) we'll need framers to begin so we'll need them lined up. And all the framing materials will have to be on hand. I assume we order all the materials, and I also assume that the architect's plans document all the building materials needed, or does the lumber yard take the plans and calculate that, or do we do that and then make the order?

We've done virtually every part of the work that is required to do additions, but never on a large scale where we need to hire people to help (though we've had family members help). And we're not as young, nor as fit, as we were when we did a lot of the different projects.

    Bookmark   March 2, 2014 at 11:04PM
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Sounds like you know quite a bit already. I learned a lot on This Old House's rebuilding the Jersey shore episodes for what it's worth.

Here is a link that might be useful: TOH Drastic Measures

    Bookmark   March 2, 2014 at 11:34PM
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Sophie Wheeler

Look at the permitting differences and cost differences of a teardown vs. an all new build. A new build will be easier to do if you've got to bring the old house up to all new codes anyway. Easier to do is lower costs. It's why so many teardowns appen. Retrofitting isn't very cost effective in the large scale project.

    Bookmark   March 2, 2014 at 11:51PM
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Good points, hollysprings.

Check if your locality has a "50% rule". If your renovation costs more than 50% of what it's worth at completion, you have to bring everything up to code. If anything's going to do it, raising a house will.

    Bookmark   March 3, 2014 at 8:09AM
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I'm surprised that you're on a SC barrier island and not in a velocity zone. The ones I know of around here (Folly / Sullivan's / IOP) are for the most part as far as I know, except maybe for some high spots. Base flood elevation may be 8 feet for your area, but IMO you'd do yourself a favor by talking to your insurance company and seeing if there was some kind of additional discount for being another say, 3 feet above. I doubt the incremental cost would be that much and you could even come out ahead after a certain number of years.

Piers, footings, fasteners and connections are something that will be taken care of by the engineer. There are a couple of approaches you could take... one of them being to have an engineer come up with the structure and design and then taking that to someone who will handle all of the permits, subs and whatnot or you could go straight to a builder who already has a working relationship with the engineer and then they basically handle it. Trying to sub this out piece by piece would be quite a challenge.

    Bookmark   March 3, 2014 at 12:07PM
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Barrier island in SC will be in a hurricane zone as the entire east coast has adopted that building code.

    Bookmark   March 3, 2014 at 7:30PM
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I think you could drive around the island and speak with people who have done this. Find out what the process was for them and how they liked their subs. A sit down with the Building Dept would be helpful as well

    Bookmark   March 4, 2014 at 10:22AM
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I have raised about 9 homes through out my career, and there are many different solutions and many different methods, however, unless the current structure is in horrible condition it is always more cost effective to raise the structure. Once you have you BFE certificate (Base Flood Elevation) and you have a soil bore test you can then determine the depth that the pilings need to reach. If you can acquire these two pieces of information you will have enough to go and solicit bids on your own. I would start by getting bids from companies that specialize in raising the structure only, then get bids from some framing companies to install the new beam system underneath the structure, then get estimates from companies to install the new pilings, these are the three major components to the project. Depending on the companies in your area you may be able to save some money by acting as your own GC. When it comes to the pilings you should consider the best type for your home. Helical piles are very popular when it comes to house raising because you dont have to move the home out of the way to install them, however the problem with conventional helical pilings is that they have weak points where the sections connect together, and due to this fact they do not have a strong lateral load capacity, so to make up for this fact engineers will spec. a grade beam poured over the tops of the pilings and then require poured concrete pilings be installed from the grade beam up to the new beam system. A new, and far more stable piling is what is called a High Pressure Grouted Pile. This new piling is installed like a helical, however it has a special grout that is ejected from the tip of drill at 3000 psi and mixes as it penetrates the ground. This piling has so much shear strength that you do not have to waist all the time and effort of building a grade beam. With this new piling you end up with a solid concrete piling 16" to 24" thick and even thicker if needed, the grout conforms to the shape of the soil and is wedged into place, and the steel in the center of the concrete can have 1/2' or even 3/4" thick walled pipe. You will also need less pilings per lineal foot of beam because they are so much stronger than conventional piles. I could go on for days about house raising, do you have any more specific questions I could help you with? Halebuilt6@gmail

    Bookmark   January 25, 2015 at 10:12PM
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