The wine shed - a concept, and some horrible maths..

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DRT
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Re: The wine shed - a concept, and some horrible maths..

Post by DRT » 01:26 Wed 07 Mar 2018

This is all very impressive stuff from a technical perspective, but given the apparent complexity of building the optimum wine shed I am very happy that I am paying Seckford Wines £7.30 per case per annum with insurance at replacement value included in the cost :D
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Re: The wine shed - a concept, and some horrible maths..

Post by uncle tom » 05:33 Wed 07 Mar 2018

This is all very impressive stuff from a technical perspective, but given the apparent complexity of building the optimum wine shed
Although the technical stuff may seem complex, the build is surprisingly simple. Unless you live in a conservation area, or want to build your shed in front of the house rather than behind it, you will probably be exempt from needing either planning permission or the rigours of building control.

Celcon blocks are inexpensive to buy and the fastest of all builds from the standpoint of a bricklayer. Indeed, none of the materials needed is costly - I estimate that a shed with a capacity for up to 200 cases (3.6m x 2m internally) could be built for around £4.5K. Even if you only used it at 60% capacity, you would recoup your investment in a little over five years, and you won't have to go trekking up the Suffolk coast whenever you need a particular bottle!
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Re: The wine shed - a concept, and some horrible maths..

Post by DRT » 11:50 Wed 07 Mar 2018

uncle tom wrote:
05:33 Wed 07 Mar 2018
you won't have to go trekking up the Suffolk coast whenever you need a particular bottle!
That raises the question of whether or not a willpower coefficient should be incorporated into the maths. My present solution requires no willpower whatsoever as I can't get to Suffolk when an overwhelming thirst emerges :lol:
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Re: The wine shed - a concept, and some horrible maths..

Post by PhilW » 12:14 Wed 07 Mar 2018

uncle tom wrote:
05:33 Wed 07 Mar 2018
I estimate that a shed with a capacity for up to 200 cases (3.6m x 2m internally) could be built for around £4.5K.
Note that the above discussions regarding thickness and temperature applied to the scenario of a hole in the ground, where the ground is deep enough to be roughly constant temperature, and the external varying temperature was being applied to a single face, and did not include the effects of radiated heat.

Once you extend the model to a "shed" (assuming one side to not-deep ground surface, and 5 sides to the external temperature, and depending on plan/structure regarding incident radiated heat), the results could be quite significantly altered regarding required thicknesses etc. So "shed" would require some much clearer definition for the context of this discussion, even at a simplified level.

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Re: The wine shed - a concept, and some horrible maths..

Post by uncle tom » 13:08 Wed 07 Mar 2018

Note that the above discussions regarding thickness and temperature applied to the scenario of a hole in the ground, where the ground is deep enough to be roughly constant temperature, and the external varying temperature was being applied to a single face, and did not include the effects of radiated heat.
The whole purpose of this concept was to get away from the 'hole in the ground' notion, which incurs a lot of extra costs that a surface structure avoids, such as the need to make the walls strong enough to withstand the pressure of the soil, the cost of removing a large volume of soil, constructing steps down as well as a door, and of course, keeping it dry.

Although radiated heat (sunlight) can raise the temperature of a solid surface above the temperature of the air around, the time taken to form a thermal gradient remains the same. Moreover, if the exterior is painted white, the increased temperature due to sunlight will be quite modest, and can be further reduced by planting vegetation close to the southern aspect of the building.
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Re: The wine shed - a concept, and some horrible maths..

Post by PhilW » 14:14 Wed 07 Mar 2018

uncle tom wrote:
13:08 Wed 07 Mar 2018
Note that the above discussions regarding thickness and temperature applied to the scenario of a hole in the ground, where the ground is deep enough to be roughly constant temperature, and the external varying temperature was being applied to a single face, and did not include the effects of radiated heat.
The whole purpose of this concept was to get away from the 'hole in the ground' notion, which incurs a lot of extra costs that a surface structure avoids, such as the need to make the walls strong enough to withstand the pressure of the soil, the cost of removing a large volume of soil, constructing steps down as well as a door, and of course, keeping it dry.
Understandable. However, someone reading this might otherwise have thought they could take the immediate result and build a structure using 30cm breeze blocks and expect the minimal temperrature variation internally without sufficiently accounting for "for the simplified one-dimensional case the final equations seem to be as follows ...". The maths is still applicable, but the next step would involve the relative external surface area to internal volume as well as thermal mass inside the unit, as well as allowing for incident radiated heat and potentially convection also. That is not to say that sensible assumptions could not be made to keep the calculation simple while minimising error, but they do need to be clearly stated to avoid others discounting the conclusions.
uncle tom wrote:
13:08 Wed 07 Mar 2018
Although radiated heat (sunlight) can raise the temperature of a solid surface above the temperature of the air around, the time taken to form a thermal gradient remains the same. Moreover, if the exterior is painted white, the increased temperature due to sunlight will be quite modest, and can be further reduced by planting vegetation close to the southern aspect of the building.
Indeed; the prior calculation assumed that the input of heat from the ground was negligible, which is probably not true for a structure on the surface; they may well be a small simple additive factor if the mean ground temperature near the surface close to the structure can be assumed to be sufficiently low and lowly varying in all conditions (I don't know whether this would be valid). On the other hand, if your structure were to have a 1m deep cement based foundation which was surrounded by breeze blocks, that would likely solve that assumption while still keeping your usable structure on the surface.

Similarly, your proposal to build the unit and paint it while all over is potential fine subject to practical questions (including a white roof? does it stay clean? is that practicable/acceptable for most people to have a 30x20ft all-white unit?). A simpler proposal (perhaps less practical) of building a separate but open roof over the unit and fences/bushes around would be equally valid and might also provide a simpler assumption to eliminate most incident radiated effects (and if designed well, could minimise convection also).

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Re: The wine shed - a concept, and some horrible maths..

Post by flash_uk » 15:50 Wed 07 Mar 2018

PhilW wrote:
14:14 Wed 07 Mar 2018
uncle tom wrote:
13:08 Wed 07 Mar 2018
Note that the above discussions regarding thickness and temperature applied to the scenario of a hole in the ground, where the ground is deep enough to be roughly constant temperature, and the external varying temperature was being applied to a single face, and did not include the effects of radiated heat.
The whole purpose of this concept was to get away from the 'hole in the ground' notion, which incurs a lot of extra costs that a surface structure avoids, such as the need to make the walls strong enough to withstand the pressure of the soil, the cost of removing a large volume of soil, constructing steps down as well as a door, and of course, keeping it dry.
Understandable. However, someone reading this might otherwise have thought they could take the immediate result and build a structure using 30cm breeze blocks and expect the minimal temperrature variation internally without sufficiently accounting for "for the simplified one-dimensional case the final equations seem to be as follows ...". The maths is still applicable, but the next step would involve the relative external surface area to internal volume as well as thermal mass inside the unit, as well as allowing for incident radiated heat and potentially convection also. That is not to say that sensible assumptions could not be made to keep the calculation simple while minimising error, but they do need to be clearly stated to avoid others discounting the conclusions.
uncle tom wrote:
13:08 Wed 07 Mar 2018
Although radiated heat (sunlight) can raise the temperature of a solid surface above the temperature of the air around, the time taken to form a thermal gradient remains the same. Moreover, if the exterior is painted white, the increased temperature due to sunlight will be quite modest, and can be further reduced by planting vegetation close to the southern aspect of the building.
Indeed; the prior calculation assumed that the input of heat from the ground was negligible, which is probably not true for a structure on the surface; they may well be a small simple additive factor if the mean ground temperature near the surface close to the structure can be assumed to be sufficiently low and lowly varying in all conditions (I don't know whether this would be valid). On the other hand, if your structure were to have a 1m deep cement based foundation which was surrounded by breeze blocks, that would likely solve that assumption while still keeping your usable structure on the surface.

Similarly, your proposal to build the unit and paint it while all over is potential fine subject to practical questions (including a white roof? does it stay clean? is that practicable/acceptable for most people to have a 30x20ft all-white unit?). A simpler proposal (perhaps less practical) of building a separate but open roof over the unit and fences/bushes around would be equally valid and might also provide a simpler assumption to eliminate most incident radiated effects (and if designed well, could minimise convection also).
I agree.

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Re: The wine shed - a concept, and some horrible maths..

Post by Doggett » 17:22 Wed 07 Mar 2018

As they say on FTLOP a lot... +1

Hadn’t realised how cheap it could be... I might build 2 at the end of the garden. Now I just need 400 cases too! 🤔

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Re: The wine shed - a concept, and some horrible maths..

Post by DRT » 23:18 Wed 07 Mar 2018

Doggett wrote:
17:22 Wed 07 Mar 2018
As they say on FTLOP a lot... +1

Hadn’t realised how cheap it could be... I might build 2 at the end of the garden. Now I just need 400 cases too! 🤔
You only need one case of Port and 399 cases of water to get going 😉
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Re: The wine shed - a concept, and some horrible maths..

Post by AHB » 18:34 Tue 13 Mar 2018

So what's the conclusion? Do I build a shed out of polystyrene bricks or not?
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Re: The wine shed - a concept, and some horrible maths..

Post by uncle tom » 09:43 Wed 14 Mar 2018

Do I build a shed out of polystyrene bricks or not?
Yes but no..

Build it, but not out of polystyrene..

1) On most sites the simplest foundation will be a rigid reinforced concrete raft. You can pay a hefty sum to a structural engineer to draw up a specification for you, or deploy a slightly over-designed 200mm slab specification that I've used several times on some pretty horrible soft clay soils, without any problems:

i) Clear the topsoil down about 9" from the surface. The surface below needs to be level and compact - you can hire compactors, also known as whacker plates. If the soil below is dry and not claggy you can set the concrete directly onto the subsoil, otherwise add a small amount of fine hardcore (usually scalpings) to level the site and assist compaction.

ii) Order enough A252 (8mm bar, 200mm x 200mm spacing) reinforcing mesh to place two layers of mesh across the slab. Where mesh sheets meet, allow at least half a metre of overlap. Thinner mesh will work, but it is springy and easily displaced when you make the concrete pour.

You can get little supports to keep the mesh layers clear of the ground and clear of each other, but half bricks work just as well. The steel must not come within 50mm of any surface of the concrete, else there is a risk of blistering (aka concrete cancer)

When ordering your mesh, also order a couple of 6m sticks of 12mm rebar to help support your shuttering.

iii) Never underestimate the ability of freshly poured concrete to push over shuttering! Get some 12mm shuttering ply cut into 200mm wide strips, then with a few blocks of timber, screw together your shuttering cage to support and form the edges of your slab. Also cut your rebar into half metre long pins with an angle grinder to drive in to support it. Make sure the shuttering is level and square - use the 3-4-5 triangle method to check the corners, and ensure that the pins are driven fully in (or cut off if not possible) so your tamping board is not obstructed. Make sure the shuttering is fully sound and rigid before ordering your concrete.

iv) Phone round your local ready mix concrete suppliers to find the one who can deliver the quantity you need at the best price. Don't try forming a reinforced slab with an ordinary cement mixer - it's very hard work and doesn't give a good result. The grade of concrete you want is called C25. You may want to include admixtures to delay setting time, or achieve a degree of water resistance - discuss with your supplier. Fully waterproof concrete is very costly however.

Consider how you are going to get the concrete to the site if the mixer can't drive right up to it. Concrete pumping trucks are fairly expensive to hire, but work really well - they can easily articulate over the roof of a house and deliver concrete accurately in the garden behind. Barrowing concrete may be an option, but you will need plenty of labour (and builder's barrows) as it's very hard graft.

Order enough to complete the job, and a tiny bit besides. Have a good use lined up for the leftovers, as concrete trucks need to completely empty themselves.

As the concrete is poured, have rakes and shovels on hand to help spread it, and then start tamping straight away. You need a good straight rigid plank for this that can span the slab - eight by two is usually favourite. Tamping has to be done by two people - one on each end with the board on edge. Keep working back and forth until the slab is nicely level.

After the concrete has gone off, don't let the surface dry out too quickly, especially if the weather is hot and dry. Use a watering can to keep it damp, but not too soon or you'll mess the surface of the slab. Keep an eye out for your pets as the concrete is setting - make sure they don't leave a permanent impression with their paws!

More soon..
I may be drunk, Miss, but in the morning I shall be sober and you will still be ugly - W.S. Churchill

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Re: The wine shed - a concept, and some horrible maths..

Post by uncle tom » 08:35 Sun 18 Mar 2018

So, you’ve got a nice rigid concrete base to build off, but will this cause thermal bridging under the walls? Will the daily cycle of outside temperatures travel down, through the slab under the walls and back up again?

More horrid maths, and the answer seems to be yes, but not massively. There seem to be four options:

1) If the top of your slab is close to the outside soil surface, and it’s a damp part of your garden, you might want to elevate the floor level to lift it clear of its surroundings. In that event, a layer of 100mm or 150mm aerated blocks laid flat across the floor will deal with both issues.

2) Placing a layer of 100mm aerated blocks beneath your thermal mass walls will reduce daily heat movement from thermal bridging to a negligible level.

3) After removing the shuttering and pins that supported it, butting aerated blocks against the edge of the slab will also be effective.

Or..

4) Do nothing and don’t worry about it..

Next up you will need a bricklayer. Your local pub is always a good starting place to find one, but a recommendation from a friend who had some good work done is better. Bricklayers often prioritise clients who offer to pay them in cash, and those working on large construction sites may be amenable to cash paid ‘overtime’ at weekends.

It’s important to make sure that everything they need is delivered to site in advance – it gets expensive if your brickie has to take time out to go to builder’s merchants.

When he first starts he will take a little time checking how square your slab is, and establishing the highest point (no slab is ever perfectly level). He will then take his time making sure the first course is correctly laid before letting rip on the courses above. Bear in mind that he will want to position the door frame first and then build up to it, so make that’s on site in advance.

He will want to lay the first course on conventional mortar so he can adjust for variations on the slab surface, but after that, discuss the option of using the Celfix thin mortar system for the courses above. This is a very quick method of laying aerated blocks which gives superior thermal properties, but not every brickie likes it.

Also discuss with your brickie what equipment he has, and what you will need to borrow or hire. In addition to a cement mixer, he will need scaffold boards and bandstands to rest them on, when he gets to the higher courses.

Blocks are normally delivered on pallets, unloaded by trucks fitted with a Hiab crane. The closer you can get the blocks delivered to the job, the better, as lugging blocks is not a fun job. If you can’t get them delivered close, borrow a sturdy sack barrow or trolley.

After the first course is laid, and assuming the blocks are close to hand, a good brickie should be able to get around 10m2 of blocks laid in a day.

As the walls are built, you will need a lintel to go across the doorframe. When it comes to building the penultimate wall course and the gables, switch from the 275mm thick blocks to two leaves of 100 mm + 150mm blocks. That way your brickie will be able to cut in the ceiling joists and purlins for your roofing sheets into the inner leaf only, leaving the outer leaf neat and tidy.

More soon..
I may be drunk, Miss, but in the morning I shall be sober and you will still be ugly - W.S. Churchill

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