Windows / Doors in Garage conversions
When installing external grade doors or windows you need to ensure all current regulations are met. The first one is ‘u’ value. Externally glazed areas need to achieve a level of retaining heat set out by building control. Double glazed windows and doors may need low emissivity glass in argon filled units. The ‘u’ value is different whether you have uPVC or metal windows. Metal windows must have a ‘thermal break’ incorporated into the design to achieve the required value. The same applies to doors. Windows must also incorporate ‘trickle vents’
Bear in mind that doors opening into a conservatory will either need to be external grade doors OR the conservatory comes under the heat loss calculations and glazed area regulations for the rest of the building. This states that no more than 25% of the TOTAL FLOOR AREA of a dwelling should be glazed. Basically if your house floor plan measures 100 square metres then you are allowed no more than 25 square metres of glass in the house. That would include the conservatory and conservatory roof (provided its glazed with either polycarbonate or glass). Exceptions can be made and usually involve beefing up the insulation level somewhere else to compensate.
Timber frames may be used but also need to achieve a certain ‘u’ value and must be rebated sufficient to carry a 24mm double glazed unit. Some older styles of window will not accommodate this size of unit so check before you order. Most newly manufactured timber windows available from timber merchants are suitable.
What you will find however is the opening across the front of the garage is not a ‘standard’ size so if you want to fit a ‘standard off the shelf window’ further construction work will be required.
For ‘fire egress’ windows certain specifications have to be met. The opening part of the window should be no more than 1100 from finished floor height. The opening should be at least 0.33m2 and open at at angle to facilitate ease of egress. The window should also pivot from the corner (fire escape hinges) and not as in non-fire upvc windows where the hinge slides inwards as its opened. ‘Easy clean’ upvc hinges satisfy the fire regulation. A non locking handle must be fitted to the escape window.
There are also regulations regarding safety glass, more applicable to doors and feature (low slung) windows. Doors must have safety glass top and bottom, be it toughened or laminated, any glazed area of a window below 800mm from finished floor height or within 300mm of a door combination also must be safety glass.
Don’t panic though, manufacturers are fully aware of the regulations so they will usually be glad to help and more often send their surveyor in the case of upvc.
If you need to give manufacture sizes to a manufacturer for a upvc window or door measure the opening at its narrowest point and knock 10mm off that size to get your manufacture size. Even better get their surveyor to come and measure up and specify the window.
A good tip for the garage front is to include a 20mm frame extension to both sides. This will enable you to use insulated plasterboard on the internal reveals without encroaching into the glazed area with final finish.
A French door or patio door may also need to be fire egress rated and would need a ‘thumb turn’ lock internally so you can get out without the key.
For more information please search the internet for approved documents relating to Glazing regulations, Fire regulations and Ventilation. Ultimate handyman no longer links to any Government website as they keep moving or deleting the pages which leaves us with hundreds of dead links on our site. We cannot put a copy of the approved documents on this server as the documents are regularly updated and so you could be viewing an out of date document.
