External doors
An external door keeps weather out, people out and heat in, which is why it is thicker, heavier and more expensive than an internal one. It is normally specified as a complete doorset, because the security and thermal performance belong to the leaf, frame, glazing and locks together.
We are still building this range, so there is nothing to browse on this page yet. Rather than fill it with placeholders, here is what we would tell you if you rang up about an external door today.
No external doors in the catalogue yet
The external range is not stocked at the moment, and we would rather say so than show you products we cannot supply. Internal and fire doors are available now.
What makes a door an external door
An external door has three jobs an internal door does not: keep weather out, keep people out, and keep heat in. Each of those adds material, and material is why an external leaf is usually 44mm thick against the 35mm of a standard internal door, and why it weighs enough to need three hinges as a matter of course.
It is also why an internal door fitted in an external opening fails, and fails fast. The core is not built for the moisture, the finish is not built for the exposure, and the construction is not built for the sun hitting one face while the other stays cold. Doors fitted the wrong way round like this twist within a season.
A front door and a back door are different problems
The front door is the one people judge the house on, and it is usually the one with the security requirement, because it is visible, accessible and the door a locksmith or an insurer will ask about.
The back door is the one that takes the abuse. It is opened more often, it is more likely to face the weather, and it is more likely to be the one that gets a wet dog and a bag of compost through it. Specifying the same door for both is common and is usually the wrong call on one of them.
Security and thermal performance, honestly
Security for doors in new dwellings in England is usually addressed through Approved Document Q, which references a security standard for doorsets, and thermal performance through Approved Document L, which sets a maximum U-value for replacement doors. Both apply to the complete doorset — the leaf, the frame, the glazing and the locking hardware together — rather than to a leaf bought on its own.
[VERIFY: Approved Documents Q and L, current editions] and [NEEDS HUMAN SIGN-OFF] on any statement about which requirements apply to a specific building. Replacement doors in an existing home are treated differently from doors in a new dwelling, and getting that distinction wrong in either direction is expensive.
The practical point when you are comparing products: a lock, a cylinder and a hinge set are part of the performance, not accessories to it. A door quoted without them is not directly comparable with one quoted with them.
Measuring an external opening
External doors are far more often replaced as a complete doorset, frame and all, than internal ones are. If the frame is staying, measure the opening inside the existing frame. If the frame is going, measure the structural opening in the brickwork, which is a different and larger number.
Say which one you have measured when you ask anyone for a price. It is the single most common source of confusion on an external door order, and the two numbers can differ by 100mm or more.