Glass roof extensions ensure your living space is awash with natural light. They now come with self-cleaning features. They provide excellent insulation. Imagine reading a book under the stars… the list goes on.
With the growing trend of glass roof extensions, our architects have compiled this handy guide. Topics covered include: planning permission, building regulations, costs, effective heating methods… and much more!
We trust you’ll find it beneficial.
Deciding whether to opt for Planning Permission or Permitted Development can be complex. Planners treat the structure (the walls) and the roof of glass extensions differently.
Specific types of glass roof extensions can be constructed without planning permission under Permitted Development.
Yet, several criteria must be met for your new glass roof extension:
If your glass roof extension doesn’t meet these requirements, planning permission will be necessary. However, this may allow your architect more creative freedom as planning policies tend to be more flexible than Permitted Development rules.
Permitted Development regulations for glass roof extensions are rather vague. The clause regarding allowable external materials states:
“The materials employed in any external work (excluding those used in conservatory construction) must closely resemble those of the existing dwellinghouse exterior.”
Typically, homes feature brick construction with slate or clay tile roofs. Therefore, any extension under Permitted Development should use similar materials.
However, the policy exception, ‘excluding materials for conservatories’, indicates that glass extensions are permissible, as they are common in conservatories.
We highly recommend obtaining a Certificate of Lawful Development from your local planning authority before proceeding with Permitted Development for glass roof extensions. They will issue a certificate confirming that your proposed extension is ‘lawful’ and would not require planning permission.
Great news! If you’ve reached this point, your glass roof extension has been approved!
Yet, some steps remain before construction can begin.
Firstly, your architect’s comprehensive plans must receive approval from Building Control. Energy efficiency standards pose a challenge with large glass areas in your extension, potentially conflicting with building regulations.
This regulation restricts the proportion of openings or glazed elements in glass roof extensions, including:
These elements must not exceed 25 percent of the extension’s floor area. For a modest extension featuring patio doors and a lantern light, this limit can quickly be reached.
Enhancing the thermal resistance of other elements like floors, walls, or the roof is one option. If insufficient, upgrading to high-performance glass with superior thermal efficiency might be necessary.
Another method involves a Standard Assessment Procedure (SAP) calculation to prove that the CO2 emissions from the extension will not exceed those from a conventional extension of the same size. Solutions might include better loft insulation or more efficient heating systems.
Conservatories can be exempt from Building Regulations if they’re separated from the main house by external-quality doors/windows and have their own heating controls. This option is less feasible for those desiring an open plan.
Pros of Glass Roof Extensions
Cons of Glass Roof Extensions
The visibility through a glass roof might raise privacy concerns. Various solutions can mitigate this:
Glass roofed rooms can feel cold in winter. However, numerous heating solutions exist:
Choosing a water-based system over electric is advisable due to lower operational costs and is a must for new extensions.
Trench heating, integrated into the floor’s perimeter, removes the need for radiators and heats the space via natural convection, visible only by its grille.
Aiming for the lowest possible U-Value in glass helps retain heat, minimizing heat loss and energy costs. Selecting glass with a low U-Value is crucial for efficiency and cost-saving.
The typical price for a fully glass roof spans from £1,800 to £2,200 per m2.
Methods to reduce expenses:
Our architects excel in creating innovative and singular extensions. That’s why we believe glass roof extensions are an excellent choice for those wishing to distinguish their homes.
We possess extensive experience in designing glass roof extensions. If you need advice or want to discuss ideas, why not schedule a free 30-minute call with one of our architects?