The windows on sheds and summer houses, workshops and log cabins rely on the windows to let light in so are crucial to your enjoyment of your new garden building. The way these windows are fixed to the building is also crucial so you need to be aware of the method used. The reason for this is so that you don't end up with leaking windows which can be a nuisance.
There are various ways as to how the windows are secured into place. You will often find that they are 'dry fixed' using timber beading. This is a very good way of keeping your shed or summerhouse dry provided the beading is pushed up tight against the glass. Some building only use small nails or brads to secure the glass in place and this can sometimes leak. Another option is with a mastic or sealant around the outside edge of the glass and the shed wall or even with sealant behind the glass.
When I had my garden shed company we use to use the dry fixing method but this was supplemented with a window ledge with a recess cut for the glass to sit into. The beadings were fixed from inside the shed or summerhouse and pressed tight against the glass. This was also more secure as the beading could not be removed from outside.
The type of windows varies from the cheap mass produced sheds which tend to have non-opening windows with plastic tacked into position. On the better sheds the windows would be sealed with mastic and, probably, have at least one opening window which can be great if you are working inside the shed. The opening window would normally be hinged from the top and would have a casement stay at the bottom of the shed window so the window can be fixed in an open position. On summer houses and log cabins the opening mechanisms can be slightly grander. You may find there is an option for double glazed windows on some summerhouses and this will help to keep the building warmer during the winter and cooler during the summer.
If you are concerned about shed or summerhouse security then it is possible to have 'security windows'. These are very narrow windows, typically only about 8" tall and 24" wide. This means that access to your garden shed or summer house is not possible through the window. If you want to have the normal size windows than you could out bars across the windows and this again will aid security.
Another good piece of advice is to put curtains up in the shed and this will stop opportunist thieves being tempted by your prized possessions You could also select obscure glass or have no windows in your shed. What the eye does not see the heart not grieve over. I think what this means if you remove temptation it will be people are less likely to want to steal.
My advice is based on 39 years in the garden sheds business and you can get more information about shed and summer house windows on this page.