Fine Doors, a UK door specialist with over three decades' experience, has set out points for buyers of wooden double glazed French doors. Part L of the Building Regulations asks replacement external doors to achieve a whole-unit U-value of 1.4 W/m²K or lower. Specification choices decide whether a door meets that limit.

Understanding U-Values and Glazing Choices

A standard 4/16/4 configuration, with a 4mm pane, 16mm cavity and 4mm pane, filled with argon typically achieves 1.3–1.4 W/m²K. That sits within the limit. Where more than 60% of the internal face is glazed, the 1.4 W/m²K figure applies. Triple glazed units start from 0.8 W/m²K, which is 43% better than the 1.4 W/m²K guideline. Customers should check that quotes state the gas fill, glass type and frame material.

Timber Types and Sizes

Oak, meranti and accoya are the usual hardwood species for exterior French doors. FSC or PEFC certified timber is standard. Buyers should ask how each species and finish is expected to cope with exposure to British weather, and how often the finish needs maintaining. Made-to-measure doors can be produced up to 1.3 metres wide, with double sets reaching 2.1 metres.

Security Standards and Locking Specifications

Wooden French doors are typically supplied with espagnolette locking, a latch and a mortice deadlock. Doors sold as security rated must satisfy PAS 24:2022 testing and use 3-star TS007 anti-snap cylinders, which gives buyers a clear benchmark when comparing quotes. Glass within 1500mm of floor level must be safety glass. It can be toughened or laminated.

Building Regulations Compliance and Exemptions

Replacement external doors must comply with Approved Document L, and the FENSA Scheme lets installers self-certify their work. Listed buildings and properties in conservation areas are exempt, as are doors with less than 50% glazing. Whether an exemption applies depends on the individual property, so customers should confirm it with the supplier or surveyor. They should also ask for installation certification before purchase.

Making an Informed Decision

Buyers should request U-values in writing, compare timber species and finishes, and check whether the property is listed or in a conservation area. Fine Doors stocks hardwood, oak and softwood doors from importers LPD Doors and XL Joinery.

About Fine Doors

Fine Doors is a UK door specialist with over three decades' experience. It supplies internal and external doors, frames, architraves, skirting and door hardware, and is an exclusive stockist of LPD Doors and XL Joinery products. Its range includes oak, hardwood and softwood doors, French and bi-fold doors, and pre-hung sets. Visit https://www.fine-doors.co.uk

Media contact

Fine-doors

Email: info@fine-doors.co.uk

Address: 47 Queens Road,Buckhurst Hill, United Kingdom

Phone: 020 8505 1333