When it comes to fitting your pond window, you have a couple of options. You can either fit it into the brickwork directly, or use a fibreglass frame.
Brickwork Option
Fitting a pond window into brickwork tends to be the more economical option.
A 45mm (width) x the thickness of the glass (depth) rebate is cut into the brickwork (an alternative to brickwork is railway sleepers) on the inside of the pond. This means that when the pond is full the glass will be pressed against the rebate by the water pressure and held in place. Make sure to cut the blocks before you lay them. Allow an extra 5mm in the height for packers to be placed under the glass.
When constructed, the brickwork will form a recess that the glass can be slotted into. The opening should be 6-10mm bigger than the glass size. This will allow for a 3-5mm gap each side of the glass (this gap will be filled with silicone). Please ensure that the cement has cured before attempting to fit the glass.
Place the packers underneath the glass and ensure that it is level along the top. Ensure the the glass is held in place with clamps at the stage. Now fill the 3 to 5mm gap with silicone. When this has dried, use cement render to fill in across the blocks to the glass to make a smooth surface.
When the render has dried, mask off the pond window glass 40mm in from the edge on the 3 sides that are set into the brickwork. This will act as a guide when you are cutting the liner.
Move the liner into place and hold it in position with some timber placed on top of the brickwork. The liner should be flat against the sides of the pond and the glass with no creases or gaps. This is very important as if there are creases or gaps present, the water pressure can dislodge the liner from the silicone.
A white pencil line can be drawn onto the liner (corresponding with the masking tape behind) to ensure that the liner extends onto the glass by 40mm all the way around.
Once the opening has been cut in the liner, the silicone can be applied to the render and the glass. Please follow the instructions on the silicone as to the amount that needs to be applied. A general rule of thumb is around 10 beads of silicone in total. Some people opt to leave the last bead of silicone 10mm back from the reveal so as to be certain to not get any silicone showing from the viewing side.
When the silicone is in place you can the lift the liner into position using the tape as a guide. Using a small amount of pressure, smooth a small section of the liner down onto the silicone using your hand. Peel back the liner and look at the beads of silicone. They should be just flattened out enough so that they are touching each other. If too much pressure is used the liner can stretch and it won’t line up with the tape. Once you are satisfied that you have got the right amount of pressure, stick the liner down all the way around. Now remove the tape. You can take this opportunity to trim back the liner if it is showing on the viewing side. Once you are satisfied, run your finger along the edge of the liner to smooth it back against the glass.
An alternative option is to roughly cut the liner (ensuring that it is extending over the glass at a minimum of 40mm all the way round). You can then apply two beads of silicone at the far edge of the render all the way round, stick the liner to them with adequate pressure and then leave to cure overnight. When you are satisfied that they have cured, add the next 2 beads, rinse and repeat until you have the required number of beads. You can now neaten up and trim back the pond liner so that it is not visible from the viewing side.
Below is a bird’s eye view of this method.
An 80mm wide strip of sealant is applied to the pond liner on all sides of the cut out for the opening. When in position, 40mm of the liner will be stuck to the brickwork. The other 40mm will be stuck to the glass. The liner that is stuck to the glass will not be visible from the outside as the rebate will cover it. Make sure to leave the last bead of sealant a slight bit back from the edge of the liner. This ensures that when you press the liner to the glass the adhesive doesn’t squish out and spread over the glass.
A second option is to use the same method. However, you would put the liner in first, siliconing it to the render. Followed by the glass which is siliconed to the liner and then pack more silicone in around the glass. Some people prefer this method as they feel more comfortable knowing that the water pressure is sandwiching the liner in between the glass and the render. One criticism is that there are likely to be more creases in the liner with it being shoved in behind the glass. Therefore if you are using this method ensure that lots of silicone is used to reduce any risks of leakage.
Top tip: leave the pond window adhesive in a bucket of warm water to ensure that it’ll come out easily.
Fibreglass Option
Another option to fit your pond window is by using a fibreglass frame.
To do this, you would create a hole in the brickwork for the frame to fit into and then render around the frame. Ensure that the rendering gives the frame a flat finish. The frame is also screwed into the brickwork for added stability (four screws would tend to be used as a rule of thumb). The rendering should allow the frame to project out slightly from the wall. Insulation (1 inch Kingspan boards) or rendering would then be applied on top of the brickwork. This will give a flush finish with the edges of the frame.
Fibreglass is then applied over the whole of the inside of the pond and over the frame itself. The glass is then installed and siliconed in to the frame.
Disclaimer: We shall have no liability for the accuracy of the fitting information above and cannot be held liable for any third-party claims or losses of any damages.