Made to measure vs standard doors: What you need to know

What is best? Made to measure vs standard doors? If you’re working on a new build with consistent, square openings that fall within standard UK door dimensions, off-the-shelf doors are a workable option. If the opening is non-standard by even 10mm, or you’re retrofitting into a period property, a made to measure door is almost always the better specification. Here’s why, and how to measure before you order.

Why standard doors fail in non-standard frames

Off-the-shelf doors are manufactured to nominal sizes. The actual door leaf will be slightly smaller than the stated opening to allow clearance for the frame, hinges and, in external applications, weather sealing. That clearance is typically 2-3mm per side on a factory-hung unit.

The problem surfaces when the frame itself is not to standard. This is more common than most tradespeople expect:

• Victorian and Edwardian housing: Openings were hand-cut. Width can vary 20-40mm from room to room in the same property.
• Post-war council stock: Frames were built to imperial sizes that don’t map neatly onto metric ranges, leaving gaps that are too wide for a standard door and too narrow for the next size up.
• Commercial conversions and listed buildings: Openings reflect original structural decisions, not modern catalogues.
• Extensions and alterations: Where structural work has been done, the rough opening may not have been checked against door catalogues before plastering.

Forcing a standard door into a non-standard opening typically results in one of three outcomes: packing the frame (which shifts the reveal and looks wrong), trimming the door leaf (which voids most manufacturer guarantees and risks warping if the core is cut into), or a persistent draught gap that no amount of draught strip will fix.

Made to measure vs standard doors: the real cost comparison

The common objection to bespoke timber doors is cost. It is worth separating the purchase price from the total project cost.

Standard door, non-standard opening:

• Door purchase: lower
• Labour to trim or pack: additional
• Return visit for adjustment or replacement: common
• Risk of gap, draught or acoustic failure: higher
• Client snag rate: elevated

Made to measure door, correct opening:

• Door purchase: higher per unit
• Labour to hang: straightforward, no remedial work
• Return visits: rare
• Performance to specification: reliable
• Client snag rate: low

For a contractor managing multiple plots or retrofit units, the labour overhead on remedial door work compounds quickly. A bespoke door ordered to the actual opening size typically saves time on site even if the unit cost is higher.

Where bespoke timber doors make the biggest difference

Period properties and heritage projects

Timber is the only practical material for conservation work. uPVC and composite doors will not pass planning in conservation areas or on listed buildings in most local authority areas. Bespoke hardwood or softwood doors can be manufactured to match original profiles, moulding depths and glazing patterns, something no standard catalogue comes close to offering.

At GB Joinery, we work regularly on heritage conservation projects across Cheshire and Greater Manchester, manufacturing doors that meet both specification and character requirements. Get in touch to discuss your project.

New builds where architect specifications diverge from stock sizes

Architects increasingly specify wider corridor doors (minimum 775mm clear opening under Part M of the Building Regulations), flush panel aesthetics or specific timber species that simply aren’t available off the shelf. Sourcing bespoke at the outset avoids the specification compromise that happens when a contractor substitutes a stock door for a specified one.

Acoustic and fire performance

Standard fire doors are tested and certified to a nominal size. Trim them outside the manufacturer’s permitted range and the certification becomes void. Where a non-standard opening needs a rated door, FD30 or FD60, a made to measure fire door manufactured and certified to the actual dimensions is the only compliant route.

How to measure a door opening accurately

Poor measurements are the single most common cause of a made to measure door arriving on site and not fitting. Here is the correct sequence:

Step 1: Measure the frame opening, not the old door.

If a door is already in place, remove it before measuring. Old doors may have been trimmed, may have dropped on their hinges or may be hung proud of the actual frame.

Step 2: Take three width measurements.

Measure the clear width at the top, middle and bottom of the opening (inside the frame rebate). Note the smallest figure, this is your governing dimension.

Step 3: Take three height measurements.

Measure from the finished floor level to the underside of the head on the left, centre and right. Note the smallest.

Step 4: Check for square.

Measure both diagonals. If they differ by more than 5mm, the frame is out of square and the door will need to be manufactured to match, or the frame will need to be corrected first.

Step 5: Note the rebate depth.

The rebate is the step in the frame that the door closes into. Standard is 12mm; older frames may differ.

Step 6: Specify the handed configuration.

State whether the door is left-handed or right-handed (standing outside the opening, looking at the face the door swings towards, if the hinges are on the right, it is right-handed).

Record all six measurements (three widths, three heights), the diagonal difference, the rebate depth and the hand. Send all of this to your supplier, not just the nominal size. A bespoke door manufacturer like GB Joinery will use the full data set to produce a door that hangs true on the first fix.

Timber species: does it affect the choice?

Yes, and this is another area where made to measure outperforms stock. Standard doors are predominantly manufactured in engineered softwood, MDF or hardboard-faced hollow cores. The range of available timber species in catalogue products is narrow.

At GB Joinery, we are an Accoya approved manufacturer, meaning we can supply modified wood doors with the dimensional stability and longevity that timber in exposed positions demands.

When is a standard door the right call?

There are genuinely situations where stock doors are appropriate:

• New build plots with consistent metric openings specified from the outset
• Internal doors on a tight programme where openings have been checked and match the 2040mm metric series
• Temporary or utility spaces where longevity and finish quality are secondary
• High-volume developments where a standard specification has been pre-agreed and frames are built to match

Even in these cases, the frame must be built to accommodate the door, not the other way around. The most common site problem is frames that have been plastered before the door supplier is consulted.

Contact GB Joinery to discuss your door specification, request a quote or talk through a measurement you’re unsure about. Call 0161 477 1818 or contact us online.