Hi, I am looking at a piece of land that has volcanic ash soil. I know that ash is very free draining so wondered if there are any special considerations for building a house! Would I be better to go for a concrete floor or piles! Is there additional expense I should expect because its not normal dirt! Tia.
steptoesnr,
Feb 19, 8:04pm
Relax-most of the north island is volcanic ash!
kcc55a,
Feb 19, 8:06pm
Get ageotech report (especially if you are considering building a 2 story) Your council might require one anyway.
febes1,
Feb 19, 9:42pm
lol at 'not a normal dirt' Can you explain what 'normal dirt' consists of I never learnt about that one. ;) As steptoesnr pointed out most of NZ (and especially the fertile dairying regions of Taranaki & waikato) is Yellow Brown Loam a volcanic ash soil type . your vege garden will flourish & your house will sit a lot saver than if you built on a sand dune or the fine silt soils which turn into 'slush' during a decent shake!
rsr72,
Feb 19, 10:14pm
Half of Auckland has long been built on deep, rich, freedraining, volcanic ash soil. Makes for wonderful gardens.
kenw1,
Feb 19, 11:18pm
You must get a Geo Technical engineer to do soil tests to determine the depth to where "good ground" is, then you will be able to determine what type of foundations you require, without this test its all guesswork.
tim41,
Feb 20, 9:41am
build a rib raft floor,job done
sonja2,
Feb 20, 10:02am
Thanks everyone. I have to google rib raft floor too now lol. I am worrying about nothing obviously.
kenw1,
Feb 20, 7:54pm
If I was purchasing a piece of land to build a house on, I would make a geotech report a condition of purchase.The difference in cost of foundations between a simple standard type and specific engineered design (sed) foundations could run into severaltens of thousands of dollars.Enough for me to worry about for sure.Before all the naysayers leap in, in our case good ground was NOT reached despite a pile being driven in 3.6m plus.
tezw1,
Feb 20, 8:05pm
How long ago was the land subdivided! A council I used to deal with required a house site to be identified and tested prior to approval of subdivision, I think this started in the 90's. I am not sure if this is an RMA requirment or council policy under the district plan, but your local council may have the information already. A LIM on the land should bring this up or go into the council and request the land file, making sure that they understand you want the subdivison file as well.
sonja2,
Feb 20, 8:10pm
Thank you very much Tezw and kenw, I will follow up on that.
rsr72,
Feb 20, 10:33pm
#11- Confusing advice from those posters. There is a massive difference between building on infilled land, and on normal clay and volcanic soil land both of which are perfectly safe and typical of Auckland. As I have said earlier, major parts of Auckland are composed of volcanic soils as all Auckland is built around volcanoes, and pose no difficulties whatsoever, indeed, they they are sought after for ease ofmodifying and planting rich gardens. Volcanic soil is nothing to worry about at all.
tezw1,
Mar 16, 5:47pm
How is it confusing to advise to do due diligence on the purchase of land! Maybe there is a recorded problem and maybe there isn't. Maybe the council will require a geotech report as part of the building consent and maybe they can rely on past history. If you talk to the council before laying out 1000's of dollars, you may save buying a lemon I have had several clients wish that they had purchased my services prior to purchasing the section, instead of after.
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