Best method for insulating

[Jon W]

Hi

I wonder if anyone has any thought on the following. I'm building a completely raised holding pond, using concrete blocks laid flat. Originally I was going to line this with Kingspan and then fibreglass. However this is proving awkward due to not being able to find a reasonable quote for the fibreglassing. I'm now thinking of rendering and using G4 or similar as a finish.

My question is, if I insulate the outside of the pond blockwork will this be as thermally efficient as my orginal plan?

Thanks

Jon W.

[dazzafjr1300]

hard to say but think about us most our heat loss is through our heads so i would worrie more about a good cover as that is my main project at the moment/i see some members have got hold of solar swimming pool covers so i am looking at that
i did consider doing what you are doing but i have a round pond pre formed 9 feet round 4 feet deep so i over gug the hole 11 inches each side and back filled with drylean concrete then a 9 inch wide wall for the 1 foot that i left out the ground also as you say the insulation you need will not be cheep .

[B.Scott]

If you are completely above ground I would insulate everything including under the base to stop the cold ground from sucking the warmth out of the pond. As dazza says a cover is also and excellent idea in the winter.

B.Scott

[Jon W]

Hi Dazza
I will definitely be fitting a cover, probably double wall polycarbonate as you're right about exposed water being the most immediate source of heat loss.

Hi BScott
What I can't work out is how to insulate the base. I am laying a concrete pad onto an existing concrete floor. I can't think of a thermal material that I could use between the 2 layers of concrete that wouldn't be deformed and cause movement due to the weight of the base and water.

Cheers

Jon

[Davej]

Hi Jon

There must be someone local who could glass the tank. How many square meters are we talking about? Worth phoning around, could be that your job could be fitted in with another so it was worth the travel down to Wales!!

Ideally you want to go down the poly foam/kingspan and glass route with a good Polycarb cover, will pay for itself in the long run.

Regards

Dave

[Jon W]

Hi Dave

The reason I've gone off the Kingspan lined/glassing route is that the only quote I have had was £18 per square metre; turned out this was per layer so in fact it would have been £54 per square metre for the proper job! It's only a 1,700 gal holding pond - once it's finished I will be building a much bigger one but I need the small one to house my fish in the meantime.

Having employed one or two people for other building jobs I'm very wary of employing anyone else who doesn't come with a really good personal recommendation and I don't know anyone in the building game in this area. A koi dealer I know recently asked me if I know of anyone who can do a good fibreglassing job so he could recommend them to his customers!

Hence have returned to the render/G4 route as I can do the work myself - just can't think of a way of insulating the base.

Cheers

Jon

[Davej]

Hi Jon

Well I know prices have gone up BUT £54 psm!!

Think you will struggle getting insulation into the base but that may be one of those compromises that have to be made.

I used KoiKote on our wildlife pond, couple of thousand gallons; thought it would have been easier and cheaper than glassing it... No way!! may have saved a few pennies but would not use it again and have my doubts whether it will stand the test of time.

If your DIY skills are up to rendering then can't see much problem with you glassing it yourself???

Regards

dave

[Jon W]

Hi Dave

I always thought things would be a lot cheaper outside of London. Because it is so remote up here anything to do with building is more expensive because there is hardly any competition plus the additional transport costs.

I'm not that keen on G4 for the reasons you've given plus if any minor cracks appear later on it would be pain trying to find leaks. Also my current pond is about 6 years old and a lot of the G4 has flaked; don't know how well it was applied because the pond came with house when I bought it. Having said all that a mate of mine is in the process of building a 24K gal pond and I've rather stupidly agreed to help him apply 5 coats of G4 as a finish (I think his plan is to have about 10 people working on it at the same time).

For some reason I seemed to develop a knack for plastering/rendering from watching others work on my house back in London. The only thing I struggled with was getting the right consistency of mix - first few attempts either went like crazy paving or slid of the float. To me glassing looks a bit of black art - one of those tasks that could go horribly wrong very easily. However if I get really desperate I might give it a go. I'd much rather insulate the inside of the pond. Problem is I need to make the decision now so that I can set the height of the bottom drain before pouring the base and I'm itching to get on with it. Might have to flip a coin at this rate.

Cheers

Jon

[dazzafjr1300]

this might sound silly but can you get gas to your pond as you could lay underfloor heating pipe work like in a house run it very low as it will cost you otherwise so a cheep boiler and pipe work i bet some one has already got it

[Jon W]

Hi Dazza

It's a good idea but unfortunately we don't have mains gas and LPG would be prohibitively expensive and would require a separate boiler. Our heating system is oil which has also risen from £300 to £1,000 for 2K litres in the last couple of years. In the future I am going to look at a heat exchange pump or solar as possible options for the house and the pond, but I'm waiting to see if the hardware comes down in price as more people adopt the technology. After reflecting on the problem I think I'm going to go the Kingspan and DIY fibreglass route (gulp!).

Cheers

Jon

[dazzafjr1300]

are you going to brick the sides ? if you are only block work why not 2 inch battons then go to builbers get 2 inch jablight sheets cut to fit the the out side some good looking timber on some of the posh sheds you see .as this is very good stuff as all new houses have this under the floors its a good cold barrier or you can blockwork then this and then brick like house cavity then you need the bottom ?i would not use as base like this.i know houses are but the floor might crack unless you dig out base lay concrete base then jablight then 6 inch on top concrete with steel bars then you are going to be ok but it wont be cheep but worth pricing all ideas are worth some thought .once you have lots of ideas you can combine differant parts
lets hope you get more help so you can have a final idea
good luck with the pond once done please put photo on

[B.Scott]

Hi Dazza
Hi BScott
What I can't work out is how to insulate the base. I am laying a concrete pad onto an existing concrete floor. I can't think of a thermal material that I could use between the 2 layers of concrete that wouldn't be deformed and cause movement due to the weight of the base and water.

Cheers

Jon

Very easy Jon,
Just lay down as thick a layer of polystyrene foam as you can get your hands on and pour the slab over the top. I have seen it done dozens of times. Polystyrene foam is very strong and doesn't compress under the weight of concrete. I have in fact even seen it used as a substrate for a motorway where the weight of the road surface was causing the road to sink into marshy ground. The put 2 meter thick blocks of polystyrene foam down and put the aggregate and tarmack over the top.
Ideally you would want about 10 cm of polystyrene foam under the slab either in single slabs of staggered layers.

[Jon W]

Hi Dazza and BScott

Thanks for the suggestions - I now know there are a couple of alternatives if I can't do the fibreglassing. However I've found another member of our club who fibreglassed his pond and it looks like he did a pretty good job. Therefore I think I'm going to give it a go which means that I can stick to the original plan of insulating from the inside with Kingspan. Once underway I'll definitely post some pictures.

Regards

Jon