Roof Window Between Rafters

The standard for roof windows is 900x600mm and these are installed between rafters at 600mm centres.

Roof window between rafters.

In finished space insulation is placed between the rafter boards and drywall or other material is fastened to the face of the boards. The windows are placed on the same level in the slope with just over 800mm of roof surface between them. So you can get small ones or wide ones or long ones but you can t get long and wide ones. The ridge board must be the same width as the rafter boards.

In heavy duty construction a ridge beam might be used instead. Standard diameters for tubular skylights are 10 inches 14 inches and 21 inches sizes that allow the skylights to easily fit between roof rafters or trusses. If you choose or need to go with an unvented roof you would need either exterior insulation or a flash coat of closed cell spray foam first then you could round out the insulation package with mineral wool. The rafters are 4inch by 2inch on approximately 400 mm centres and extend around 7ft from purlin to ridge apologies for mixed units.

We install windows on rafters when the window width matches the spacing between rafters it ensures stability of the construction and the durability of the connection. Velux roof windows for example are available in sizes from 470 x 980mm to 1340 x 1600mm and 940 x 550mm to 780 x 1800mm angus says. They can also be provided in much larger sizes for example glazing vision pitchglaze windows can measure up to 3000x1000mm. Roof construction and timbers framing a roof window if your roof window fits between existing rafters or truss work it can be just a simple job of fitting the window to the existing woodwork or adding some timber framework to take plasterboard at a later stage.

Other common sizes are 980x980mm and 900x1200mm the latter is designed to fit in a double rafter space. Installation on rafters is recommended especially when we replace old windows in already existing roofs with new ones or when we install big windows. Choosing windows narrow enough to fit between roof rafters or trusses is a good idea that will keep your costs manageable. Widths tend to be based on the standard spacing of timber roof rafters.

If you have an easy roof to vent and decide to go that route you could use mineral wool insulation between the rafters and beneath the vent channels. The polished tubes that carry sunlight into the room can be extended to reach through any attic space to the ceiling of a room below.