The roof lantern upstand in detail.
Building upstand for roof lantern.
These double timbers are called trimmers.
Current building regulations state that the upstand must protrude at least 150mm above the finished roof surface and are typically made of timber.
An upstand be it against a parapet penetration or facade ensures that the waterproofing does its job and that exposed brickwork external facades or other building elements are not flooded or saturated.
Upstands need to protrude by a minimum of 150mm above the roof and have a pitch of a minimum of three degrees.
All our roof lanterns shown on this website are designed to be fixed onto a kerb like detail which rises proud of the supporting flat roof assembly precisely at the open edge of the lantern aperture.
Upstands are used to keep the glazed section of the rooflight off of the roofs surface.
The cut ends of the rafter joist will need to have new support introduced usually achieved by fixing two pieces of timber together which span across the new opening on either side.
Sponsored by made for trade.
Measure the timber to timber hole and deduct 30 mm from the length and width this will make the roof lantern overhang inside 15 mm all the way around to allow room for plaster work see diagram.
The job of an upstand sometimes referred to as a kerb is to lift the glass element of your rooflight off of the roof s surface and is required by building regulations for safety and weathering reasons.
For every roof lantern we supply we will provide a plan and section drawing detailing the correct measurements for the builder to work to.
Screw a timber down around the hole approx 100mm high and 70 mm wide making sure the size of the hole does not change.
An upstand is the fixture that keeps the glazed unit from coming into contact with the surface of the roof and is needed for most building regulations.
To install a rooflight in a roof generally entails cutting part of one or more of the roof s rafters or joists away.
The upstand must be at least 150mm in height and should a minimum pitch of at least 3 degrees.
On exposed membrane roofs the upstand height is measured directly from the membrane surface.
Obviously written communication with drawings plan and section is absolutely essential in order to ensure good detailing between our roof lanterns and the builder s supporting kerb upstand.
Upstands also help protect against rainwater bouncing up off the finished roof surface.
Darren collins 4th september 2017.
Rainwater can build up on a roof during heavy storm events and it may be stating the obvious but unless checked this water could spill into building and saturate construction elements electrical installations as well as internal finishes and effects.
Set out the timbers on the flat roof leaving a hole where the roof lantern will be fitted and allowing enough room for spotlights if required.
