First questions on owning a lifestyle block - driveway construction.

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3 years 4 months ago #553390 by Pat1
Hi all,

New member and (soon to be) lifestyle block owner here...

I've been reading up as much as possible about what to expect when we finally get to move onto our land and will no doubt have lots of questions along the way but I have an initial question about the best way to build a driveway.

For background - we've agreed to buy a hilly piece of land in the Wellington region. At the moment we're working with the vendor (who's chopping our land out of a larger block that he owns to put a drive way into the site - completion of the driveway is part of the sale agreement. The drive will be around 400m long and up to a 1:5 gradient (at a guess).

The driveway has been cut into place - its fairly steep but should be manageable if we can find a good way to surface it. The contractor doing the work had a first attempt using tarmac scrapings, but due to lack of drainage/camber (and I think using old dry scrapings) the surface was destroyed when it it rained heavily - see attached pictures.

So, does anyone have any experience in steep driveways? A proper tarmac road (i.e. as you'd build a residential road) would be great but prohibitively expensive so we're probably looking at another go with scrapings (with better drainage and possibly a base layer underneath?) or just using gravel (large pieces to start with then building up with smaller diameter in future years)?

Suggestions gratefully received!
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3 years 4 months ago - 3 years 4 months ago #553391 by Stikkibeek
Drainage with culvert crossings to take the water to the outer side, absolutely essential and they should be either big enough, or frequent enough to deal with cloudbursts as well as normal rainfall. Layering the bottoms of the drains with rocks also helpful to prevent scouring, also on the discharge side, or, concrete spillways. You should seek advice from a number of driveway contractors as to best practice. To get an impervious surface, you may need something as durable as either tarseal properly done or, concrete.

Did you know, that what you thought I said, was not what I meant :S
Last edit: 3 years 4 months ago by Stikkibeek.

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3 years 4 months ago #553396 by Ruth
I'd be insisting on another contractor for a start: what an idiot! Water flows and takes whatever is in its way with it, unless there's an easier channel. You have to have water-courses alongside hard tracks and roads.

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3 years 4 months ago #553397 by Pat1
Thanks for the replies.

Yep, drainage is key so whatever happens that'll be sorted.

I also don't have a lot of confidence in the current contractor so am inclined to go with someone else but at the end of the day everyone has their opinions and I don't know how to tell what's best (given budget constraints).

I should also note that the drive is has a softer clay like base on the upper section, but is hard as on the lower where it's been cut into the bank. I guess the softer section should have more prep work ie a decent base layer of rock compacted into the soil before the top layer is put on to the whole drive?

If anyone's dealt with a similar drive I'd be grateful for your thoughts...

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3 years 4 months ago #553398 by LongRidge
My suggestions ...
With tracks on hills the sideways slope of the drive must be into the uphill side. This is so that if your vehicle slides then it slides into the "water table" rather than over the bank. These photos (which may be wrong) show both edges level. The "over-the-bank" edge should be higher than the middle and the middle higher than the left edge.
I have 5 culverts under our 500 m drive, but would have needed 7 or 8 if I had not been able to drain some of the rainwater into paddocks, where there is no risk of slipping over a bank.
I used to keep the water-tables clear of grass and weeds, but lost a lot of the drive grit. I was then told by a professional road builder to make small dams in the water-table to slow down the flow and catch the gravel before it is washed away. This does mean that the water-table has to be cleared regularly by shovelling the grit and dirt out and back onto the drive.
The last lot of gravel that I got was too clean, too even sized, too small, and too much, so it is rather like driving on marbles. Next time I am going to get the equivalent of AP 40 (everything smaller than 40 mm) with more fines in it. The neighbour has done this and the surface is much better, even though it is less blue and more brown than ours.
You will need a drive gravel leveling device of some sort.

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3 years 4 months ago #553399 by LongRidge
And don't forget to have a couple of passing bays. If one of the vehicles has a trailer on it can be very difficult to back it.

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3 years 4 months ago - 3 years 4 months ago #553400 by Hawkspur
Dealing with water is critical for reducing maintenance requirements. As is the subsurface being strong enough to take the loads of vehicles and their accelerations/decelerations.

Contact your local council regarding what gradient is acceptable for a driveway. Here the maximum gradient for a sealed driveway, if straight, is 1:5. (Parts of ours are 1:6 and those bits wear very quickly and some front-wheel drive vehicles lose traction in dry weather.)
Curves complicate things, but generally the gradient is measured in the centreline around the curve.

1:5 is too steep for a non-sealed surface, because a vehicle pushing up that steep a slope will just move the gravel rather than the vehicle so you will need to be regravelling and grading it constantly.

Depending on the grade of road you are coming off, there may also be requirements for sealing the first few metres, so loose gravel doesn't damage the sealed road, and angles of approach, sightlines, space for accelerating/slowing, width of access, turning areas, letterbox positioning etc.

Also contact the local Fire and Emergency about what they require for access. Here, they want 4 m wide by 4 m high clear hard surface tracks - wider around corners, with a turning radius of 20 m. You may need to meet their requirements to get permission to build. It varies among the Councils.
Last edit: 3 years 4 months ago by Hawkspur.

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3 years 4 months ago #553407 by StephHarmon
Buying land you'll want to consider any existing easements, roads, driveways ... Ultimately, you want a property to suit your lifestyle, and the home you want to build.

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3 years 4 months ago #553412 by max2
I second going to Council to arm yourself with information and what their rules and regs are, and then my next step would be some sort of engineer to plan and design the works.

That driveway is going to be an essential service to you for the rest of your property ownership and something that you are likely to need to use on a daily basis. It simply has to be done right!

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3 years 4 months ago #553424 by ritchie1
Don’t forget that the road will also be used by large vehicles when it comes to building...concrete trucks etc....but no doubt you’ve thought of that.

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3 years 4 months ago #553495 by Pat1
Hi all,

Just to say thanks for all the advice. Our driveway has now been updated with additional drainage and better quality tarmac scrapings laid.

I'm still not sure how well it will last in the longer term, but we've agreed with the vendor to give it a couple of months to settle down through usage/sunshine then assess what if anything else needs to be done (prior to us completing the purchase). Fingers crossed for a day or two of torrential rain at some stage to give it a good test (this is Wellington so probably won't have to wait long).

Thanks again

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3 years 4 months ago #553502 by LongRidge
Remember that driveways need lots and lots of maintenance, especially on slopes. Ours gets levelled about monthly, along with the shingle raked out of the watertable, perhaps a bit less often if you have got the right gravel. Our current gravel is not right so it needs raking every month too.

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3 years 1 month ago #554119 by flyingkiwi
I'm a little surprised that the council gave resource consent for a subdivision without specifying what the driveway standards would be? When we looked at a divided section it was all spelled out: width, camber, drainage, material, the works. Maybe check your property documents and make sure what's happening lines up with what's required there?

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3 years 1 month ago #554126 by Pat1
The resource consent granted gave pretty rough details on the driveway requirements - I was also pretty surprised.

In the end we decided that the access wasn't going to be suitable for us, and used a sunset clause to pull out of the purchase. The search for a new site continues...

If anyone wants to buy a site in Ohariu Valley with 'challenging' access I'm happy to pass on their details!

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3 years 1 month ago #554129 by linrae
That will feel like winning Lotto

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