Hopper windows don't offer much ventilation - they only open a narrow strip at the top - but they are watertight even when open as long as the wind isn't strong enough to drive the rain up over the open glass. If there is sufficient clearance above the window, the glass can be lifted out for more ventilation - but of course it then has to be stored somewhere where it won't get broken!
The 'glass' can be either plain glass (with polished edges) or plastic that can be cut at home. The drainholes shown in the first illustration are important (!) and sealed with epoxy resin, they shouldn't give any rot potential, as they used to.
The green external trim ring is purely cosmetic.
Weatherseal (weatherstripping?) is shown in grey - I've incorrectly shown it along the bottom where it should be left off, so that any rain can drain into the internal gutter and then out the drainholes.
The old-fashioned turnbuckle fastening has several purposes:
- it holds the window closed (!);
- it can have a wedge shape to clamp the glass agasint the weatherseal;
- the mounting block under the glass stops the glass from being able to move upwards when being towed.
If anyone wants these and other illustrations in a pdf, email me.
Andrew
angib (at) blueyonder (dot) co (dot) uk
