Site Setting Out, Levels : Help Me Think This Through
Posted 19 January 2016 - 09:20 AM
For your piles are you casting a reinforced slab on top of the piles or using steel and concrete and tying all the piles together to make a ring beam around the outside.
Posted 19 January 2016 - 09:20 AM
I found that, when talking to the ground works guys, just explaining exactly why we had to have such tight tolerances on some things (like the positions of pipes and ducts that were going to end up coming through the slab) worked wonders. There's loads of stuff where 100mm here or there makes no real difference, so I just let them get on with it, there were only a handful of things where I had no choice but to insist on really tight positioning.
The outcome was pretty good, in fact the ground works guys had a couple of ideas that improved things, one being making up the ground where the treatment plant was fitted, which gave a better fall to the soil pipe and allowed a sort of "emergency" siphon emptying option for the discharge (I suspect our treatment plant discharge would "auto flush" if the pump failed, because of this).
Posted 19 January 2016 - 09:36 AM
Methinks there is an element of over-thinking at work in all this.
Outside of purely academic interest, it really is a very simple process as the existence of buildings with spot-on elevations, built in the pre-technology age, testify.
I've seen experienced JCB guys level plots in a few hours depending on nothing but their eyes and the seat of their pants, leaving a situation where the builder need only to spend the rest of the day with a dumpy marking out the site ready for the JCB to return the following day to dig the founds.
Bit like brickies or chippies using a level just to check that they've still got it right.
Posted 19 January 2016 - 09:55 AM
Posted 19 January 2016 - 10:11 AM
In terms of building, by the time you've all got to where you are, you've all forgotten how much you learned and how painful it was when, (in your 20s?), you got it (doesn't matter what 'it' is) badly wrong a few times, got bollocked for it and have now forgotten. All experts think learning 'it' is easy. And they do so because of the tricks that memory play.
Imagine having to break down the simple act of using a shovel efficiently while not killing your back and being able to shovel a few more tons each day for the next week. Not so simple then is it? And yet you all know how to do it, I bet. Watching your wife / children/ partner bravely helping you shovel a load off the trailer reminds you how much you really know. And how teenagers really hate you for knowing it!
I'm quite deliberately trying to expose, and subsequently document, the learning process involved in levelling (because that's what I do well, and have many years of experience of putting this kind of stuff on line as a learning resource).
My end-in-mind is to put together a very basic, simple set of steps to help anyone who wants to establish the levels on their own site. And then share it here.
Because of the generosity of spirit which exists in this site. It's one way I really can return the kindness.
Posted 19 January 2016 - 10:47 AM
It's why people who call themselves "sash window specialists" stay in business and drive shiny new vans.
Once you've actually shown someone how to do something they've expressed wonder and admiration for, the reaction is usually: "Well, I'll be damned."
Posted 19 January 2016 - 01:46 PM
I do love Victorian houses but too often we hold their builders in too high regard. They were mass house builders,ultimately.
Posted 19 January 2016 - 02:37 PM
Posted 19 January 2016 - 04:06 PM
There is an old married quarters estate near here (built circa 1938) and you stand at the end of a row of ten semi-detached and look down the front or rear elevations and there is perfect alignment.
Likewise, this place is late-Victorian and diagonals across rooms are spot-on. Out of curiosity, when I was renovating the place and intrigued by the accuracy of the build, I checked the diagonals from each bottom corner to opposing ceiling corner and the 18' x 18' x 11' sitting room was 3/4" out. Disgracefully sloppy. Mind you, it could have been the cornice moulding that was so wildly out!
Incidentally, on a serious note, what's the tolerance for the site layout in preparation for a factory-made timber-framed house?
Edited by joiner, 19 January 2016 - 04:07 PM.
Posted 19 January 2016 - 04:20 PM
Around +/- 20mm I think, in the X/Y plane, less in the Z plane. For ours it was essential that the insulation around the slab lined up perfectly with the outer edge of the insulated frame, hence the need for tight tolerances. The vertical tolerance has to be tighter to both ensure everything is square and because the airtightness relies on the sole plate being tight down to the slab.
Edited by jsharris, 19 January 2016 - 04:23 PM.
Posted 19 January 2016 - 07:32 PM
In terms of site clearance your guy will have to separate out (a) good quality top soil which you will need to retain on or off site; (b) clean hardcore which you might want to retain, but local farmers or the like will usually take off your hands; (c) uncontaminated subsoil which you might want to retain on site for your own fill, or you can dispose of for minimal cost and the main cost is the round-trip time for hiring the 20-tonner; (d) any mixed or contaminated soils which can only be dumped in a registered site and each load will cost £×lots. So you really need your contractor to be careful in properly segregating out (d). You've also got the whole issue of temporary surfaces.
Yup, the Victorians and even the Romans were brilliant civil engineers this was all done by pick, shovel and wheelbarrow. A decent CAT caterpillar can pick up a couple of tonne in a single scoop. What do you do if you've realised that you've taken half a dozen 20 tonne loads too many off site?
My personal view is that you (or someone that you trust) should be on top of all this. Yes, you might be in the situation where your ground-works guy is brilliant with a dumpy and cut and fill calcs, but then again you might not. So even if he is, I would still recommend that you need to verify before you trust.
Edited by TerryE, 19 January 2016 - 07:33 PM.
Posted 19 January 2016 - 08:04 PM
Edited by joiner, 22 January 2016 - 06:37 AM.
Posted 19 January 2016 - 09:41 PM
And that is being handled by my CDM Coordinator.... through the new regs.
Posted 19 January 2016 - 11:26 PM
Edited by TerryE, 19 January 2016 - 11:27 PM.
Posted 20 January 2016 - 07:47 AM
That verification process is part of the 2015 regs. Have a look at this summary page 3, Employing.
It's not guidance to which I slavishly adhere. For example in terms of verification of competence, I've asked my mate (CDM chappie) whether he is competent to ask the correct questions to judge the competence of any trades person. To which he replies that he follows the framework of competence offered by the relevant trade. And what happens when a perfectly competent person doesn't have the relevant 'ticket'? Or as I put it - have succeeded in the University of Life (Lancaster Campus).
To give a simple direct example of how this affects me, we are building in Durisol. Can you find anyone who's competent building with that system oop North? Well, so far I've found one builder - retired and now in a wheelchair.
So, together with our architect, our building team is off the NSBRC sometime this summer to do a course together : four-men-in-car all the way to Swindon and back. Durisol put on courses for neophytes like me to become competent.
But in H&S terms, currently, we should not even consider our builders to put up a house.
A good dose of common sense, some good will and a sense of humour hitched to the H&S wagon is what's needed.
Posted 21 January 2016 - 10:47 PM
The vertical tolerance has to be tighter to both ensure everything is square and because the airtightness relies on the sole plate being tight down to the slab.
Ahh.. Thats what expanding foam's for
Posted 22 January 2016 - 05:37 PM