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Specification
Knowledge Centre
What is permitted development, what is not, and how the National Park, conservation areas and listed status change a specification. Plus the regulations that always apply.
Flagship guide · 10 min read
From the first conversation about draughty windows to the day the fitting team leaves, a glazing project has a natural sequence. This guide sets it out in full, so you know what to expect and when.
Flagship guide · 3 min read
A fire rating is decided by where the door sits, not by what it is made of. Here is how to work out which of your openings need one, and who signs it off.
Planning & Regulations · 3 min read
Most window and door replacements do not need planning permission, but several common situations change that answer.
Planning & Regulations · 3 min read
Conservation area status does not ban new windows, but it does change what needs permission and what a planning officer will expect to see.
Planning & Regulations · 3 min read
Listed status makes consent a legal requirement for almost any change, but it also opens the door to some excellent heritage-specification alternatives.
Planning & Regulations · 3 min read
Building regulations apply to nearly every window and door replacement, regardless of planning permission, and cover far more than just thermal performance.
Planning & Regulations · 3 min read
Fire safety touches glazing in two distinct ways: providing an escape route, and in some cases resisting fire itself. It pays to know which applies to your project.
Planning & Regulations · 3 min read
A bedroom above ground floor usually needs a window that can double as an emergency exit. The dimensions are specific, and worth checking before you order.
Planning & Regulations · 3 min read
Energy regulations for glazing have tightened steadily, and most homeowners now choose a specification well above the legal minimum rather than to it.
Planning & Regulations · 3 min read
Part L is the specific regulation that sets the minimum energy performance for replacement windows and doors. Here is what it actually requires.
Planning & Regulations · 3 min read
FENSA is the scheme that lets a window installer self-certify building regulations compliance without a separate building control application.
Planning & Regulations · 5 min read
The National Park is not one rule applied everywhere. What matters for your windows depends on the building, its status and where it sits — here is how to work out which of those apply to you.
Planning & Regulations · 3 min read
The eastern edge of our working area runs into the Yorkshire Dales. The considerations are close cousins of the Lake District's, with their own authority and their own emphasis.
Planning & Regulations · 3 min read
Most homeowners have never heard of Article 4 until a planning officer mentions it. It is the single most common reason a window replacement unexpectedly needs an application.
Planning & Regulations · 3 min read
What the regulations ask for, what certification proves, and the paperwork worth keeping.
Planning & Regulations · 5 min read
Short answer: often yes, sometimes no, and it depends on the building rather than the material. Here is how conservation officers actually approach aluminium windows.
Planning & Regulations · 4 min read
Short answer: colour can matter as much as material in a conservation area, and changing it can be more sensitive than a straight like-for-like replacement. Here is why, and what to check first.
Planning & Regulations · 4 min read
Short answer: glazing bars are one of the most closely examined details on a period elevation, because they carry more of a window's traditional character than almost anything else. Here is what to know before you specify them.
Planning & Regulations · 5 min read
Short answer: replacing an existing door or window opening with a sliding door usually falls under permitted development on an unlisted house. Enlarging the opening, or a listed or conservation area property, changes the answer. Here is how to tell which applies to you.
Planning & Regulations · 4 min read
Short answer: rooflights on an existing roof slope are frequently permitted development, subject to specific limits on how far they project and how high they sit. Conservation areas, listed buildings and roof extensions change the position. Here is how to check yours.
Planning & Regulations · 3 min read
Sometimes, but never assume it. Enlarging an opening can fall within permitted development on an unconstrained house, and almost never does on a listed building or a principal elevation in a conservation area.
Planning & Regulations · 3 min read
Usually because the two properties are not in the same planning position — different designation, different elevation, different history, or work done before the current rules applied.
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