The pros and cons of post pier building with tall posts

[tikicarver]

Thanks Hotzcatz

Those are some great references..

I see the problem now..
Not really a big deal to add shear walls between piers, it would just be some extra 2x4s and plywood.
(my current house built in 1997 has these)

But the now code says:

”Cripple walls shall be supported on continuous foundations.”

That is the killer for post an pier fondations like typical Hawaii houses of the past.
Just imagine, you want to build just a simple rectangular house, says 20'x30' and have it on post and pier.
Now you have to have the shear walls on each corner, that would not be too bad, but you also have to have a continuous footing under all of them. That will be a lot of extra work.
I understand now why people are saying it is easier to just pour a slab and build on that.

[hotzcatz]

Yup, the new code isn't Hawaii friendly at all. One of the best parts of post and pier was that it could build a house on a non-flat area. Put down "tofu" blocks (concrete footing blocks) and then whatever length of post was necessary. Now, with the continuous footings, they all have to be tied in together so there's at a minimum, a concrete 'beam' tying them together.

Hmm, wonder if an on the ground tie-beam would work? Build it on top of the ground instead of in ground. Easier than using a jackhammer in Puna.

The code changed to where they now specify the required shear wall length depending on the length of the house above. It used to be a percentage based on how many floors were above.

[tikicarver]

I don't understand why they want the concrete beam. I have seen many post and pier type houses in many parts of the country and none of them have this beam.
The big different, the piers were not like "tofu" blocks, they were always in a hole in the ground. Usually about 4 ft deep to get below frost line, concrete poured in place. But since we don't have freezing temps i would think just going down 12" to 18" into the lava and pouring a pier with a sonotube, then having a post connector wet cast in place and attaching the post to that would be plenty strong and not go anywhere , even in an earthquake.
It would be farly easy to build this way.

I seem to remember reading the shear walls need to be 55% of the length of the wall.
But I may be mixing that number up with somehting else...

So I guess this means when I see some new construction with a house on the pre-cast blocks and a post attached and that is all they have,, that is dead give-away that it is not permitted...lol

[hotzcatz]

Yup, the 55% was from a previous version of the code, now they just tell you the length required depending on the length of your wall. Also, the 55% was for the first floor of a two floor structure or the first and only floor. There was a lot of modifiers.


For an earthquake, I think attaching the piers to the ground would transmit more energy up to the house, with the on top of the ground stack of concrete blocks, the whole thing would kinda dance in unison. But, they now want everything stuck to the ground and inflexible. I just try to get things to meet code, I don't even ask why the code is the way it is anymore.


Yup, new construction with only precast footings is a building without a building permit. If it is an accessory structure - i.e. not a dwelling, then it could still be a legal 'no permit necessary' building. If it's a dwelling, then no permit and no hope of getting a permit until it's rebuilt to current code.

[Arktikos]

Here is a good summary of the pros/cons. The new Hawaii code is absurd IMO.

https://www.homesteadinhawaii.com/wh...ff-the-ground/