Wall Foundation

RustyPhat · 14-08-2011, 09:17 PM

Hello,

could i just ask what you guys do as far as foundations for walls go? i know some of you do full concrete slabs but how deep do you do these? and what concrete mixes do you use? thanks

Yateleyred · 15-08-2011, 11:54 PM

Quote:

Originally Posted by RustyPhat

Hello,

could i just ask what you guys do as far as foundations for walls go? i know some of you do full concrete slabs but how deep do you do these? and what concrete mixes do you use? thanks

Imagine you are building a house wall, depending on the sub soil etc governs the depth of foundations.A helpful guide would to ring your local planning officer at the council. He will know the area and how deep and wide the footings should be based on the type of sub soil you have. The depth of the pond is not the question (you may need 12" footings you may need 36" footings )Once the footings are dug and concreted, I would lay a concrete slab re-inforced with steel bar or mesh from builders yard and must put a bottom drain in.The base will then be supported by the foundations and the steel.Then concrete blockwork 6" thick or hollow blocks with steel rods in the hollows and when complete backfill the outsde with a concrete slurry mix.
The inside can then be rendered (making sure you use glass fibres to re-inforce the rendering) and then painted with G4 or fibre glassed over.
The mix for foundations and floor should be 5 (20mm balast) to 1 cement with a waterproof aditive mixed in.
Hope this helps, hard graft but worth it, especially if you want a shaped pond.
regards

Doghouse Riley · 16-08-2011, 10:32 AM

I'd echo that, the weakest point is usually the joint between the base and the first course of blocks. With a fibreglassed block-built pool, the slightest movement could crack the skin. Backfilling is essential and it can be difficult to get it compacted in some circumstances.

A level floor of the pool will always result in debris and detritus accumulating on it, especially if it has corners. No pump pulling through a 4" pipe can keep such a large are clean.
The whole of the floor shoould have a "fall" towards the bottom drain th movement of the water will help sediment move towards the drain.
Also, fish naturally scour the bottom of a pool picking stuff up and dropping it again whilst looking for food, a fall in the floor will encourage the stuff to move towards it.
Also if possible, the return from the filters should be arranged to effect a clockwise rotation in the pool, as this is the natural rotation of water down a drain. (It's the reverse in the southern hemisphere).

JoSo Steve · 16-08-2011, 10:51 PM

Evening All

Right i'm going to put my view's forward on this subject.

I take it your looking to build pond walls below ground?

I build ponds for a living & i'll be brutally honest here, DONT WASTE YOUR TIME DIGGING SEPERATE FOOTINGS & the cast your floor slab in after it's just a disaister waitng to happen, it doesn't matter how well you try & join the 2 together with rebar/dowel bars etc you have 2 cold faces of crete that will move.................simples!!

Just puor a simple base over the entire area of the pond floor including were your walls are going & allow a good 6" bearing outside the back edge of blockwork, its a solid floor of about 200/250mm thick with a single layer of A192/242 mesh spaced on plastic or metal chairs of about 90/100mm, this allows 100mm cover of crete below the mesh & around 100/150mm above the mesh.

A slight fall of around 1" from the corners of the pond towards the bottom drain is more than sufficent to keep the floor free of rubbish............. the water has only got 1 place to exit the pond & travel to the filters & thats through the B/D, so water movement around the pond will sort it out.

Dont bother using hollow blocks, ther a false economy all that filling with crete & rebar is pointless, use 7kn 4" concrete blocks laid flat, this gives you a 200mm thick wall without all the hassle of backfilling hollow's........................that's so 1970's.

As for movement on the bottom course of block if you lay em right on full mortar beds they aint goner move, when you get to render the walls put a nice fillet joint of 45 degrees between the wall & the floor, this will prevent debris build up on a dead 90 degree angle, it also make's it easier to fibreglass as there are no tight corners to deal with!!

Daran · 17-08-2011, 06:39 AM

Quote:

Originally Posted by Yateleyred

Imagine you are building a house wall, depending on the sub soil etc governs the depth of foundations.A helpful guide would to ring your local planning officer at the council. He will know the area and how deep and wide the footings should be based on the type of sub soil you have. The depth of the pond is not the question (you may need 12" footings you may need 36" footings )Once the footings are dug and concreted, I would lay a concrete slab re-inforced with steel bar or mesh from builders yard and must put a bottom drain in.The base will then be supported by the foundations and the steel.Then concrete blockwork 6" thick or hollow blocks with steel rods in the hollows and when complete backfill the outsde with a concrete slurry mix.
The inside can then be rendered (making sure you use glass fibres to re-inforce the rendering) and then painted with G4 or fibre glassed over.
The mix for foundations and floor should be 5 (20mm balast) to 1 cement with a waterproof aditive mixed in.
Hope this helps, hard graft but worth it, especially if you want a shaped pond.
regards

I know where Im going in the event of nuclear war

Mattsville · 17-08-2011, 10:21 AM

Quote:

Originally Posted by Doghouse Riley

Also if possible, the return from the filters should be arranged to effect a clockwise rotation in the pool, as this is the natural rotation of water down a drain. (It's the reverse in the southern hemisphere).

Haha - interesting fact here (I'm stocking up for when I'm invited on QI). I'm no expert on the base construction - but don't worry about whether the flow is clockwise or anticlockwise - both will work fine!
The idea of water always going clockwise in the northern hemisphere and anticlockwise in the southern is a myth - and it's incredible that everyone believes it and nobody has noticed that it's not true! I'm no different - I believed it unquestioningly before checking the facts. The direction of water coming into a container and the container shape outweigh any effect from the eath spinning by factors of millions to one in everyday use!

To be completely factual here - the effect DOES exist - however experiments have shown that in order for it to actually be observable you have to have a PERFECTLY spherical bowl and the water in it has to be PERFECTLY still. The experiment I read about found that a bowl of water had to be left undisturbed for 18 hours before it was still enough for the effect to be observable consistently.

So if you'd prefer an anticlockwise flow then that will be fine as well.

Matt

Ned · 17-08-2011, 10:45 AM

WARNING - Do not use waterproofer in reinforced concrete. Unless you are well clued up on it's content. Many cement additives including some waterproofs are corrosive. Corroding steel will cause the concrete to blow.

Doghouse Riley · 17-08-2011, 11:14 AM

Quote:

Originally Posted by Mattsville

Haha - interesting fact here (I'm stocking up for when I'm invited on QI). I'm no expert on the base construction - but don't worry about whether the flow is clockwise or anticlockwise - both will work fine!
The idea of water always going clockwise in the northern hemisphere and anticlockwise in the southern is a myth - and it's incredible that everyone believes it and nobody has noticed that it's not true! I'm no different - I believed it unquestioningly before checking the facts. The direction of water coming into a container and the container shape outweigh any effect from the eath spinning by factors of millions to one in everyday use!

To be completely factual here - the effect DOES exist - however experiments have shown that in order for it to actually be observable you have to have a PERFECTLY spherical bowl and the water in it has to be PERFECTLY still. The experiment I read about found that a bowl of water had to be left undisturbed for 18 hours before it was still enough for the effect to be observable consistently.

So if you'd prefer an anticlockwise flow then that will be fine as well.

Matt

Don't shoot the messenger chum, I'm just relaying an interesting fact of nature.

Mine actually has an anticlockwise flow, check the videos, due to the way the pipework has to enter the pool.

Mattsville · 17-08-2011, 12:41 PM

Quote:

Originally Posted by Doghouse Riley

Don't shoot the messenger chum, I'm just relaying an interesting fact of nature.

Mine actually has an anticlockwise flow, check the videos, due to the way the pipework has to enter the pool.

Sorry mate, that wasn't meant to be offensive at all! I'm not shooting the messenger just wanted to point out that there's absolutely no reason to try and have a clockwise flow if anticlockwise is easier - or vice versa. And also just to bring up a point that I find interesting and amusing (ie the fact that almost everyone firmly believes this and quotes it when it is completely untrue!).

I just wouldn't want anyone to worry about having the flow going the "right" way based on an urban myth! I'm going to embarass myself here and let you into a secret - the only reason I looked into this carefully is because I was thinking of designing my returns to make sure there was a clockwise flow myself, when anti is actually easier!