[Caretaker]

Now I know this forum is for allotments but I have always got very good help in the past.
I have a raised pond built with bricks, the size is only 2 feet deep by 3 feet wide and 15 feet long, it runs along the side of my path.
It is split up with 2 walls with small water fulls, the pump takes water from the far end and pumps it to the other end.
Hope you get some idea as to how it is, well after painting it at £60 a tin and using 2 tins I decided to get a liner that worked great.
Now I have decided to empty pond, clean liner, knock down the 2 inner walls that would leave one long pond, put in liner then, build the walls on top of the liner, a much neater job.
Now the water fulls, I would use like shutters that would slide in two groves to adjust the hight of the water flow.
What I need to know is, can I cement bricks on top of the liner then paint with pond paint.
The bricks would be done by a professional brick layer.
Please don't ask me to add a picture, to tricky.
If this is a no no, I will get back to my allotment.
PS. my wife thinks I'm mad.

[Lardman]

I doubt you'd get any adhesion between the pond liner and mortar.

How much lateral force would be on the bricks ? you might get away with a construction grade adhesive.

[8doubles]

Have a look in your local aquarists and you should find some sealant they use to join the glass on fish tanks. Aquasure or similar ?
A fillet of mastic applied either side of the walls after they have dried should stick to the liner and hold them in place.

As Lardman said it all depends on the difference in levels and pressure of water

[JayG]

My RHS-published  "Water Gardening" (by Peter Robinson) includes a section about building streams and falls using liner and blocks mortared directly onto the liner, used for structures both at and below the water surface.

I can't comment on how well it works but they are obviously happy to state it in black and white (I have mortared edging bricks directly onto the liner without problems, but they are not in direct contact with the water.)

One thing to bear in mind is that the more mortar there is in contact with the water the more leaching of lime will take place, which you need to bear in mind especially if keeping fish.

[fatcat1955]

Install the bricks then run the liner up onto the first course and secure with contast adhesive. I have just put a mdpe membrane on my extension roof and this is what they tell you to do.

[Alastair-I]

Now I know this forum is for allotments but I have always got very good help in the past.
I have a raised pond built with bricks, the size is only 2 feet deep by 3 feet wide and 15 feet long, it runs along the side of my path.
It is split up with 2 walls with small water fulls, the pump takes water from the far end and pumps it to the other end.
Hope you get some idea as to how it is, well after painting it at £60 a tin and using 2 tins I decided to get a liner that worked great.
Now I have decided to empty pond, clean liner, knock down the 2 inner walls that would leave one long pond, put in liner then, build the walls on top of the liner, a much neater job.
Now the water fulls, I would use like shutters that would slide in two groves to adjust the hight of the water flow.
What I need to know is, can I cement bricks on top of the liner then paint with pond paint.
The bricks would be done by a professional brick layer.
Please don't ask me to add a picture, to tricky.
If this is a no no, I will get back to my allotment.
PS. my wife thinks I'm mad.

Yes.

As long as the mortar is given time to fully cure (not just go-off, ieally a couple of weeks at least) before the pond is re-filled there shouldn't be a problem with leaching.  The problem will be getting a water-tight seal between the bricks and the pond wall and bottom.  Using a painted pond-sealer may not achieve this.

You'll probably need a thick, heavy wall to give it enough weight to hold position.

When the pump is running, the seal between brick and liner won't be critical, as the flow through the "official" channel will be great enough to mask a slight weep.  But when the pump is switched off you can expect the upper level to continue to drain slowly into the lower level so you need to build in enough freeboard or a catchment tank where the pump sits that can accomodate this excess without flooding the lower level.

Just as an alternative.. have you thought about paying a bit extra for a box-welded liner if the sides and base are square.  If you go this route, consider putting the wall in first and using two box-welded liners - one for the upper level and one for the lower level.  The uppper liner could include an oversize  overflow channel welded into the design, into which you build your adjustable weir.  You secure the weir mechanism over the liner into the walls of the pond (without compromising the liner by cutting through it) and then you only have to seal the edges of the weir.