Results 1 to 15 of 15
Thread: Cavity Block Build
-
07-07-2020, 09:54 AM #1
Cavity Block Build
Hi,
Thought I'd create a separate thread rather than this get lost in my main build thread.
My pond will be 2.5m x 4m x 1.5m with a smaller raised pond of 2.5m x 1m x 0.6m to be used as an anoxic filter and waterfall return. I'm pretty much settled on a cavity block build with vertical rebar and backfilled with concrete. My pond will be rendered and painted rather than fibreglassed.
I've also seen others not using mortar between the cavity blocks. I'm not sure of the advantage, but will likely mortar.
I will have vertical rebar for support. Do I need to add horizontal rebar for additional support? I noticed this on a couple of builds on a US forum and it's not something I considered or noticed with builds here.
I'm likely getting into the realm of over-engineering.
-
07-07-2020, 02:33 PM #2
This is the sort of thing I'm talking about. Seen it done along straight sections and also bent around the corners for additional support. Not done at every layer of bricks, but at bottom, middle and top of build for stability.
Do people do this and I just didn't cop it previously or is it overkill?
rebar.jpg
-
07-07-2020, 02:37 PM #3
These blocks appear to have a groove for laying rebar horizontally. I'm thinking it's probably worth doing for the price of a bit of extra rebar.
I'd hate to have the job of demolishing this pond in the future
https://grange.ie/builders-providers...y-blocks-215mm
-
07-07-2020, 02:48 PM #4
I've just doubled the size of my pond and the extension is built with 9" hollow blocks dry stacked (no mortar joints).
I've installed rebar into every hollow chemical anchored it into the concrete base and filled the hollows with concrete.
I also ran a horizontal rebar every other course which is also chemical anchored into my existing pond wall.
Not sure how much of your pond will be out of the ground but for the cost of a bit of rebar I would install as much as you can.
-
Tropheus Thanked / Liked this Post
-
07-07-2020, 02:51 PM #5
-
07-07-2020, 04:32 PM #6
i built my pond using those, just bedded the 1st course and drilled holes in the slab every other cavity for the rebar, dry stacked the blocks and filled the cavities with concrete, really fast build and easy too. no need to chem fix anything or for horizontal rebar in my opinion, ill warn you those blocks are HEAVY though
-
07-07-2020, 06:53 PM #7
-
07-07-2020, 07:15 PM #8
rebar aint going anywhere when its incased in a 4 inch column of concrete, just drill a hole and drop it in
-
Tropheus Thanked / Liked this Post
-
08-07-2020, 03:45 PM #9
-
Tropheus Thanked / Liked this Post
-
08-07-2020, 07:22 PM #10
If you decide to bed the blocks in mortar make sure the mortar does not impede you pouring concrete down the insides of the cavities. Stacking them without mortar and then pouring concrete into them with rebar will make a very strong wall.
-
Tropheus Thanked / Liked this Post
-
08-07-2020, 07:28 PM #11
-
09-07-2020, 07:51 PM #12
-
09-07-2020, 08:32 PM #13
Yes, I've given it a lot of consideration. I'm in Ireland and, unlike the UK, ponds of this scale are rare and we don't have people that specialise in this area.
I reckon it would cost in excess of €2,000 and could end up being a bad job as the person how does it will never have done one before. I also have no control over them using a fish safe product.
If this changes and I decide to do it in the future, I can go that direction. For them moment it's being painted.
I understand why you're asking as it's rare to see a painted pond on here.
-
09-07-2020, 09:04 PM #14
Have a word with Ken Alexander on here about fiberglassing and yes it isnt cheap but its permanant. you will be having to repaint quite frequently loosing good water and filter bacteria. Plus where do you put your fish whilst doing it?
If its square or rectangle or a simple shape you can get box welded liners too
Last edited by algarth; 09-07-2020 at 09:06 PM.
-
09-07-2020, 09:53 PM #15
I had paint on my previous pond done 3 years ago and it was still perfect.
I appreciate it's not as permanent as fibreglass, but just not an option.
I had a word with Ken and he has no plans to travel to Ireland at the moment. The cost of expenses on top of a single job wouldn't be viable.
The Daily pond temp thread
Pond still covered, currently 11.6C Been really mild this year as far as pond temps go. ...