Browse Forums Owner Builder Forum 1 May 12, 2013 2:39 pm Our block has a slope of 500 from front (higher) to back (lowest) and from right (higher) to left (lowest). I want to level the land so that it is the same height as the highest point of our land (front right corner). Which requires me bring in fill. Looking to build a double storey, H1 slab. My question is; - is this recommended, as building on 'filled' land can cause foundation problems down the line. - will my site costs rocket sky high? because i've effectively raised the land level 500mm, also; - who do you call to make sure the land is suitable for slab construction? (to compact the land etc and make sure it is stable), before handing it over to the building company. OR am i over thinking this too much? and there is nothing to worry about? Re: Leveling Land 2May 12, 2013 3:50 pm A lot of builders are suspicious about building directly on fill. Even when they place the fill themselves most will want to put concrete piers through to the underlying original ground (see http://www.anewhouse.com.au/?p=2858). They will also want to use a stronger slab to span between the piers. It really up to the builder to put the foundations required as they have to guarantee, and pay for insurance against foundation problems. The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: Leveling Land 3May 13, 2013 8:03 pm Before i decided to be an owner builder, I spoke to some volume builders about my sloping block. They all said they would cut and fill as part of the quoted price. As far as who can do the job, most demolition and excavation people will have access to an excavator and dump truck to bring in dirt or take it away, then use their tracks to compact the site. Assume you won't need to make any retaining walls? No issue with this approach, the engineer will assess and provide a suitable design accordingly. Re: Leveling Land 4May 14, 2013 12:50 pm There is a little bit more to it than just having a bobcat roll over your own fill as I have found out with my build. There are 2 ways engineers recommend fill be placed, rolled fill or controlled fill. Rolled fill is where the excavator dumps the soil in the fill location and rolls it just at the top to reach the required levels. Controlled fill is where the excavator places the soil in 150mm increments, rolls it with a weighted roller (my guys used a HUGE road roller!), watering each layer, repeating in 150mm layers until the height is reached. This controlled fill then needs to be assessed by a civil engineer for shear and compression (a bit like the old key in the cricket pitch test they used to do) to see if the fill is done correctly. However with controlled fill, your soil from the cut may not be suitable for use in fill. Your engineer needs to make that decision after having seen the cut out soil and having arranged for a number of tests on the soil. compaction and shear testing I believe. Why the difference? Well if you use rolled fill, all of your slab footings need to go through the rolled fill and down into natural ground. Whereas with controlled fill, your slab footings just need to go down the required depth into the controlled fill as specified by your engineer. This of course could be a rather large difference in depth of your footings. This leads to another expensive item from your concreter called 'blindings'. As I have just discovered (and hopefully avoided), concreters calculate their price by the area of the slab and the volume of footings that go into natural ground. If there is any difference between natural ground and the bottom of your slab, which will occur in rolled fill, you are up for blindings. Concreters generally don't calculate this cost until it is actually poured and currently runs at approx $300m2. If my builder had stayed with rolled fill, I could have been up for another $18,000!!! in blinding costs. Talk to you engineer to get the appropriate type of fill confirmed for your block. Regards RiH Re: Leveling Land 5May 15, 2013 10:20 am 500mm over the block isnt really a great deal depending on the size of the block that is which you havent mentioned. You really need to tell us how much fall there will be over the building envelope. I would be trying to have a convential slab built so you dont need to built on fill. Also make sure your rebate is down to ground level so you dont have to bring in soil to hide slab. Re: Leveling Land 6May 15, 2013 11:24 am the slab would cover approx 260m^2. there is a fall of between 100mm to 1000mm over this slab. (most will be around 700mm-1000mm - im estimating approx 80% of the slab). i want to level from the street, as i dont want the house to be below street level. but my block slopes down 1m (from street to back of block - 35m long). and block slopes 500mm from right side to left side of block. approx 17m. the house will cover most of this block. only a 7-10m backyard. without me leveling, or doing anything. the builder wants to do a drop edged beam on the left side of the slab, as well as parts of the front n back Re: Leveling Land 7Jan 02, 2014 9:51 am We are having the same issue with our site. Ours has a 3m slope down from right to left, but actually has a 600mm slope from left road to back. At the beginning I told the builder I wanted to cut & fill the block to be level with middle rear level, which he said ok. But then... On our first tender plan they placed house we originally chose crooked on the block with a drop edge beam... This added $33,000 to site cost (I near on fell off chair). I vetoed that & am now going with a narrower house. But also want to get a structural engineer to come in to help with excavation & retaining walls along all boundaries, which we have to supply anyway. I'm thinking if I use the builders recommended engineer there cant be any issues, also the progress from excavation to build will be smoother. I hope yours & ours works out to benefit everyone. Re: Leveling Land 8Jan 03, 2014 1:43 pm First you say the slope from front to back is 500mm, then later 1000mm. Which is it? Why do you wish to be at streetlevel? IS it stormwater drainage? If not not, I think you are making mountains out of molehills. 500 - 1000m drop over 35 m is not much really, but I guess you want a flat block for some reason? Controlled fill is the usual method , with use of a compactor and a compaction report. Most slabs are built on cut and fills using this method. Re: Leveling Land 9Feb 25, 2014 11:42 am I think having the house sit at street level is a wise investment for drainage and also street appeal. Have you considered the first level have a few steps and working the design to follow the contour of the land? This would avoid a huge cut and fill meaning less excavation costs. A 500mm fall would mean maybe a couple of steps down in your entry or from hallway to living depending on the design. Yeah I don't know why I came to a forum. Place is full of wierdos/pedos thought internet may help but I suppose I'll try my luck with someone in person. Cheers. I tried… 0 6441 Need advice on the backyard plan above. Should I excavate and cut all of the dirt to level with the house slab or semi-excavate as per photo above? Both left and right… 0 24862 13 6632 |