Raising a house 150 - 200mm

Looking at a house, that needs to be raised by 200mm really.

It is on piles and there is already good crawl access under the house, but it is on the edge of a flood plain, and either needs to be moved forward by 7 or 8 metres and up, or stay where it is and be raised.

Feasible to insert doubled up 8 x 2 across the pile lines, giving the extra height, not really keen on packing the piles.

The services are easy to lift up that amount so going up, not forward is the preferred option.

Any ideas or opinions before I call a professional, its always good to have some pre knowledge. Thanks

Call a professional. This has been done (raising floor levels) with homes in Chch where they suffered pile damage in EQ's requiring replacement, but were also in flood zones.
AFAIK the maximum allowed to pack existing piles is 50mm.
If you want to go up 200mm and there's a perimeter foundation, then that's probably going to have to be replaced.
If it's got a cladding system attached to the framing (ie weatherboard) then that makes life much easier. If the cladding is supported by the perimeter foundation (ie brick) then that makes life much harder., with full reclad and ply bracing put over the framing so it doesn't fall to pieces when lifted.
The ones I've seen done, they've lifted the houses on heavy steel beams high enough to give good clear access, replaced all the piles and ring foundation, then lowered them back down to the new level. With some older homes, if there's space available to do it, then they've detached the house from the foundation, but rather than lift it then drop it back down, parked the house to the side somewhere while they rebuilt the foundation, then shifted it back - so you may find that the best option is to shift the house onto new foundations on the higher part of the site - another advantage there is that the new foundations could be built and ready, and everything accomplished in one movement.

They've even done this with some slab on grade homes, single story and simple (close to rectangular) floor plans, but the cost for larger and more complex floor plans, two story, and/or clad with heavy materials, more often they'd just demolish them and rebuild - as the less expensive option.

Thanks.

No ring foundation.

A straightforward single storey house built on timber piles with clear ground access on all four sides.

I edited my post above. I reckon that you may be best to plan to shift the house to the higher ground. In that case you'd have extra cost of shifting services (water/sewers/power etc) but if you'd end up with a house totally clear of the flood risk, that's a much better outcome than having a house sitting in a pond when it floods, even if the water is below floor level.

You might even be able to get an idea of cost from a house shifting company having a quick look on site, and a builder to do the new foundations and other work, add perhaps $10k for consents and design work etc, total cost may be less than you think.

Ring set of new piles around the outside of the house.
Lift the house up on to Steel beams placed under house.
Reattach services etc & build a nice deck on the extra beam width.
Bonus clear space under house with no piles

The water is only a 1:100 year issue, it is very quick to rise and very quick to recede, there is no sitting in a pond, it is up for a matter of a very few hours, I am told.

planning on a long life ?

One can never tell, for my perspective yes, but several others have had a different opinion.

Thinking of getting the diggers in next month to complete the moat.

goodness me. opinions and ideas from here. You know that everyone here who has an opinion is always right and will poo all over anyone elses.

If the house is raised where it currently is to avoid flooding conditions, would access to it when there's flooding be under water? Would you need to raise the access so that's higher too, or would it be better to move the house to the higher ground - especially if the access to it wouldn't be affected by flooding?

1:100 year flooding is a lot more often in many places around the country than once assessed to be. I'd go with having the house level and access well above the 1:100 assessment.

Adding. maybe talk with neighbours for some info about what happens when flooding occurs too. or any other issues there may be, so you have more info about the area/site.

I had my house raised 600mm, with new concrete piles and H4 piles. Cost $4000.

Hi can you let me know the name of the company that did that for you, I'm think of doing the same. T.I.A.

OT a bit, but could someone tell me please. There is no vehicle access here
Do you need vehicle access to raise a house.

It was 25 years ago. I doubt the company exists now. They were just general builders. They later put another story on the house.
They must have hired jacks. To lift a house by 200mm or more the whole house would have to be raised at the same time, otherwise windows could break. So that means about 30 or more jacks are needed, or some steel beams. They could be carried by hand if necessary.
I have seen a house raised using hydraulic jacks outside the house with steel beams across underneath. The truck with the hydraulic pump was about 20 metres away from the jacks.