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Retroanaconda

New workshop project

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12 minutes ago, Cynic-al said:

The ones that fit in the aperture usually run between a couple of bits of angle / u channel. The only concern I would have with a wide one is if you give them a push in the middle they pop out the runners at the side so I would make sure it's strong enough for your needs. 

Or put a removable post in the middle to stop this.

Mike 

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If the limits are set correctly, the door reaches the bottom and then continues to unwrap, putting pressure on all the joints until it's all rigid. On the widest doors (like mine) the side guides are 90mm deep. All in all it's a pretty rigid door when closed.

They are available second hand, I sold my old one (a bit bigger than 4m x 2m) for £450 after many years service. It's a major job to cut one to size if you are tempted by one that is a bit too wide but fitting behind the side piers does give some flexibility in that respect.

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My roller shutter door is ~3.4m wide and you'd have to push it fairly hard to pop it out of the runners - but at the end of the day if someone wants in through a door like that it's only a roll of corrugated steel, just like an up & over could be prised/folded open etc. etc.... ultimately it's on a tin shed which could be opened with a tin-opener anyway.

The insulated section door is much more rigid as the sections are ~50mm thick foam-filled:

IMG_2267.JPG

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Our garage door is similar to Peaklanders.... Cost installed was round £1400 I think....

Or how about sliding doors to maximise space in the roof and floor etc. ave them opening along the right hand wall ....

hormann-side-sliding-sectional-door-slide-01.jpg.7ee942903bdea625d21ef5c8d653c378.jpg

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Problem with sliding doors is all that lost wall space for storing junk... errr useful spares.....

 

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On 4/3/2019 at 4:32 PM, bishbosh said:

Problem with sliding doors is all that lost wall space for storing junk... errr useful spares.....

Could put pallet racking in front of the wall. Probably with some thin-ish sheet ply on the back to stop anything getting pushed back and fouling the door. Although that'd be a nightmare dirt trap, so maybe better to just stack the shelves properly...

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I’ve been looking at the site and thinking about the base today. There is a slope towards the rear corner of the garden, which is part of a general slope backwards along the plot. I’d like to have the workshop floor level higher than the ground in order that I can have a small flat (ish) area in front of the doors. This lead me to consider the method of doing the floor slab - building up off the ground rather than digging down into it too far. Also has the advantage of reducing the amount of spoil that requires relocating.

The floor needs to be at least 100mm thick, with reinforcement at half the depth. And I want a good 150mm of compacted sub base underneath, plus the blinding sand and DPM.

Due to the slight slope I wondered if it would work if I were to dig a trench foundation around the building footprint and put concrete in it. Then build a wall up to the finished floor height all the way around. Excavate interior to required depth, add sub base and blinding then pour a slab up to finished wall height within the blockwork walls. Something like the sketch below (slope exaggerated and blinding omitted for clarity).

Is there any reason why this would not work? My only concern is the blockwork wall on the bottom side resisting any side load from the compacted sub base and concrete slab within. It will also be more work to build than just laying out a sub base and pouring into a timber formwork.

9088C777-DEEE-45B3-A1D5-F9B924AA6FA7.thumb.jpeg.9685146fcb02a6ad89d80df727155332.jpeg

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For very little extra I got (if memory serves) C5 or C7 edit: C35 grade fibre-reinforced concrete delivered that requires no rebar etc., it's the grade they use for factory floors etc. and the mixer truck driver thought it was massive overkill - but it adds little to the price and is much stronger than regular household grade. It's got shredded polypropylene fibres in it (a bit like GRP) that bind it together.

Likewise, getting it delivered by a ready-mix truck was a little more than home-mixed but oh so very easy and quick. You just need to make sure there's a spot for the truck to dump any surplus and wash the ramp and you're golden.

Some concreting discussion on a very old thread here:

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51 minutes ago, landroversforever said:

I don’t think the Fibre replaces rebar entirely :unsure:

I agree with Ross. My brother used it in his last garage and it cracked hence I used rebar in mine.

Mike

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To clear up the fibre debate - fibres, either polyprop or stainless are absolutely not a replacement for reinforcement. They are there to reduce cracking in the concrete due to shrinkage as it cures. They do add a little to the tensile strength of the mix but nothing like what reinforcement does.

Regarding the blockwork wall solution to overcome the gradient, in principle it should work but you need to make sure the wall is strong enough to resist the compaction forces and then the wet concrete pressures. You will also need to think about the reinforcement detailing around the edge as you will get more settlement on the deeper subbase than the interior. However, the edge is less likely to be heavily loaded so may be a case of 6 and two threes. (unless you put engine blocks on racking around the edge!!) I would suggest you spend a few hundred quid getting a structural engineer to design something for you that is correct for your site and planned usage as then you will a) have a base for your workshop that you know is fit for purpose and b) have some PI insurance to claim against if it doesn't work. In the project budget that isn't a lot to spend in my opinion.

Getting structural engineering advice off the internet (on a LR forum!! :D) is just dangerous in my opinion.

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Thanks. I'm aware of the risk of uneven settlement over the width however as you say really this is limited to the edges. It's likely that there will be a width of 8" or so at the most of backfilled sub-base at the interior of the walls, and with the weight of the structure itself sat on the blockwork rather than the slab I think the risk is minimal. The undisturbed ground in the centre will be excavated to allow for the depth of compacted sub-base and the concrete itself but should provide good support underneath. I'm not entirely sure yet what the ground is like, the whole area was once slate quarries so there may be all sorts under the ground. Some trial pits will help with the design I am sure.

As for the strength of the walls, you're right in that structural engineering advice is not best sought from a Land Rover forum. However we do have a lot of members with experience of this sort of thing so there's no harm in asking. I'll chat with some engineering coleagues at work, but as the height of the 'wall' is going to be so small (less than a foot unsupported) I think the side loads will be minimal, both during compaction, pouring, and the static load of the slab.

Using the wider hollow concrete blocks, with rebar reinforcement tied into the trench foundation, would be a belt-and-braces approach. In all likelihood the standard 100mm blocks would suffice.

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Not that I'm in any way a builder / structural engineer but that's the way I would approach it. If your worried about the top blocks being pushed off by the fill get the hollow blocks and once you've built the wall up throw some lengths of rebar down the holes and fill the holes with concrete. It'll lock the blocks together fairly well. 

Alternatively you could shutter it and pour concrete walls with rebar mesh in. No joints then. You can get the plastic ties etc to hold it all in place. 

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After discussions with some engineering-type people their recommendations were to do as Al suggests in the last part of the above post and pour the ‘walls’ in concrete which will form the foundation with the slab.

Something like this:

2D2C7DD9-0A8C-4D37-9A60-658F7F92DAD1.thumb.jpeg.1c56c306757fd02189617214af2257e2.jpeg

 

The depth of the walls/foundations can be as required for the soil conditions, however having dug out and poured a new base for the oil tank this weekend I can safely say that the ground is pretty hard with a fair bit of rock/slate in it. I can also add rebar to increase their strength if required, though I doubt this will be necessary.

I’ll be able to do it in two pours which will have the benefit of making the logistics easier and also allowing me to properly compact the type 1 up against the well set walls and lay a DPM on top. The outer shuttering for the walls will be over height by the depth of the slab and remain in place until the final pour is done, with the inner shuttering being removed when the type 1 is set in place.

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Alas it seems the idea of doing it in two pours (i.e. walls first and then the slab on top) is going to increase the cost significantly as both the local concrete companies will charge you for the full mixer truck even if you only have a part-load. As such it would be most economical for me to have a design that enables one pour as the two smaller ones will be far below a full load. I can do this by pouring the walls and the slab in one, however this will require laying the type 1 sub-base without the outer walls in place.

Can it be compacted with a chamfered edge on it so that I can taper the fill on the low side? Or will I need some kind of retainer to allow for proper compaction? I would assume the latter - I could build a timber retainer to compact against which is then removed prior to the pour, or even just left in there and buried under the slab (risk of rotting and settlement there though).

WAR_JPA19127_4909_001.thumb.jpg.9f73212fcf6d0d7080a78597191d90d0.jpg

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Please bear in mind I'm Dutch, live in France and several people claim I have "something with concrete"....

image.png.7bf4ca17c3c019f4a9ed9ff9e998a045.png

We build the ABRI on a slope - over 14 mtrs. it drops 1 metre and I was not happy the various builders suggested.

image.png.563d73b89e2a90dbe0a98fb3eb27a88e.png

Eventually we did it all ourselves and started with a wall to stop everything from sliding down. De dug into the oroginal ground and poured concrete to make them stay up. Eventually we poured the slab in 3 portion but let the armour (rebar as you call it) go across the 3 parts. 2 years on there is no crack etc. If you have to pour in 2 stages make the rebar stick out and it worked here. However, I suggested getting a truck deliver the stuff and pump it out. Better quality and you make great progress in 1 go.

image.png.7bf70a35fc4eb2cbb102b6582379d846.png

Eventually, floor was in and the roof put up.

image.png.6c3f6d12bc12a9992749c2083527b64d.png

Pallet of blocks

image.png.e4bbadca40217a01cb0c4395b42a371e.png

Finished....

image.png.7073bd22dde0a49b53b95d4d8669422b.png

13 x 6 x 3,25 mtrs.

The next one will same construction - but about 40 x 6,4 x 4 mtrs......

 

 

... and after that one the workshop between this ABRI and the house..

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" Are you opening an airport Arjan? "

😂

image.png.426e03006d2c204e2a9d33da78b099f9.png

.... this doubles as an HeliPort.......

22 mtrs. Round Pen.

 

(P.S. This was a serious digging project with 1,3 mtrs. hight difference....)

 

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3 hours ago, Retroanaconda said:

Alas it seems the idea of doing it in two pours (i.e. walls first and then the slab on top) is going to increase the cost significantly as both the local concrete companies will charge you for the full mixer truck even if you only have a part-load. As such it would be most economical for me to have a design that enables one pour as the two smaller ones will be far below a full load. I can do this by pouring the walls and the slab in one, however this will require laying the type 1 sub-base without the outer walls in place.

Can it be compacted with a chamfered edge on it so that I can taper the fill on the low side? Or will I need some kind of retainer to allow for proper compaction? I would assume the latter - I could build a timber retainer to compact against which is then removed prior to the pour, or even just left in there and buried under the slab (risk of rotting and settlement there though).

WAR_JPA19127_4909_001.thumb.jpg.9f73212fcf6d0d7080a78597191d90d0.jpg

 

You could shutter around the sub base with concrete blocks instead of timber, this will remove the worry of the timber shuttering rotting over time.

When pouring, remember to pour the wall foundations first and then onto the base...ie don't shove it in the middle and sweat trying to push it onto the edges.

Have a chat with the guy on the mixer truck, they're usally pretty good if they know what you're trying to achieve and will be patient with you.

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Burying the timber shutter wont be an issue and will be cheaper than using concrete blocks ( which are equally fine!) . Yes it will rot but that is of no consequence in my opinion.

You could also batter the slope or bench the slope which would require no formwork internally but would require more concrete. :)  This is the route I would go down personally.

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Some concrete companies have part loads to get rid of. So if you can do short notice you may be able to assist them in having a hole ready.

Mike

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“Shuttering” with concrete blocks was my original plan, and would work but would cost more as I’d still end up paying for a full load even though I’d need half of one. If I can do it all in concrete then I can use the full amount I pay for, plus don’t have to spend time laying blocks. Though I will explore the part loads thing, thanks.

I suppose in the worst case scenario where the internal shuttering rots then I’ve got two cavities 18mm wide under a 150mm reinforced slab with a span of 4m. In all honesty it’s unlikely to cause a problem, but it’s not a particularly neat solution and I’d also be concerned that it will compromise the DPM that will go over it.

Battering the slope across the site would work however I’d have to remove and dispose of a hell of a lot of spoil in order to get a good sub-base thickness under the whole slab. I’m not sure I understand regarding stepping it though, I can’t see how you can step the sub grade without having internal formwork to retain the compacted sub base on the ‘upper’ level?

Though I see the French/Dutch method doesn’t involve any sub base at all!

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Posted (edited)

I would put steel in the wall atleast, otherwise it's a long span to not crack. 

If the ground is good solid soil and compacted, your not disturbing it by digging etc and your putting a thick layer of concrete in then I think you could get away without the sub base. If the concrete slab has steel in and is of good strength and thickness then it's going to hold together as one and spread the load out pretty well and at the end of the day the sub base is only sitting on that same soil. It's only having a shed and a car on it. Depends what your ground is like I guess. Not that that's correct I'm sure!

We have mini mix companies around here with 3 cube lorries instead of the bigger 6 cube. We also have the ones with the screw mixer on the back so they will meter out whatever you need. Not sure if they work out any cheaper?

Make sure the company get it from a proper batching plant with a high speed pan mixer, I got a load once and I'm sure they were just mixing it in the back of the lorry, one end was all stone and the other end was a clump of cement. Hopeless!

Edited by Cynic-al

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".. Though I see the French/Dutch method doesn’t involve any sub base at all! .."

Eeehmm... We used the poles to "anchor" the slab. These poles go about 175 - 190 cm. into the ground, before we started adding layers to level it out.image.png.d99bfa00dc7324b061f5f7a89b1d67f0.png

These 6 poles were 1st set into the original ground, the "gravel" was added, compacted and the concrete poured in 3 sections.

image.png.c02b2d2d33081e53acea6876f71148e4.png

The slab that sits higher (on the left) has what you call a "sub base" that goes 180 cm into the ground as we will be building the workshop on there eventually and to prevent the whole thing from sliding (there is a road behind the house 3 mtrs. below the floorlevel and the ground is not always very compact / stable) so we needed it to "bite" into the set ground. That slab (3.3 x 9 mtrs. used 8 trailer loads of concrete - about 11 mtrs.3 and that is a serious amount of concrete.

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What if you dug the bit where your floor is going, compacted the sub base, then dug around it for the wall? You'd lose the edges but that would fill with concrete? 

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