
Where do You fit the frame if it is not aloud to let any wieght go against a lintel. Please bare in mind the lintel itself is 75mm high and if installed correctly should have 150mm bareings either side of the opening. Doesnt leave many places left to drill and fix it. Besides that You would need a window frame 300mm wider than the opening and atleast 90 mm higher. That way You can be sure there will be no sideways pressure on the lintle.
sillyness.
I hate to say it,if You get settlement in a way that will effect You window opening, block or Brickwork You are in trouble anyway. As this would mean Your base has settled or even worse broke its back.
I have to say Yes a frame is only a small cost towards Your pond build, but I think it has been proven time and time again a total waste of money. When there ways just as effective to get the same results at practically no cost.
Justin