TL;DR
- The survey is the technical visit that turns your order into a manufacturing specification, separate from the sales appointment and usually carried out by an installer or surveyor.
- Expect external and internal inspections, multiple width and height measurements, diagonal squareness checks, threshold and floor-level readings, and sub-frame and lintel assessments. Photos and notes go into the manufacturing file.
- The visit can adjust manufacturing dimensions, lead times and pricing in either direction. Rotten sub-frames, damp, lintel issues and access constraints are far cheaper to handle now than on installation day.
- Prepare by clearing access, knowing your priorities, flagging known issues, and mentioning listed or conservation-area status. Confirm Part L compliance and FENSA or CERTASS certification before signing off.
The door survey is the most important visit a homeowner often pays the least attention to. By the time the surveyor arrives, you have already chosen the product, agreed the price, and signed the order. The conversation feels routine, the visit is usually short, and most homeowners assume nothing significant is being decided. The truth is the opposite. The survey is the appointment where a sales decision becomes a manufacturable specification, where structural issues with the opening get caught before they become installation-day problems, and where the difference between a quote and a final invoice is settled.
This guide walks through what actually happens during a UK door survey, why each check matters, and how to make the most of the visit. By the end, you will know what the surveyor is looking for, what questions to ask, and what to do before the appointment to make sure the installation that follows is as smooth as the brochure promised.
A door survey is also a useful moment to think about the wider look, comfort, and performance of your home. If you are planning other improvements, it may be worth comparing your options for replacement doors, energy-efficient windows, made-to-measure shutters, or practical blinds, especially if you want the finishes, insulation, and privacy levels to work together across the whole property.
What is a door survey?
A door survey is the technical inspection of the opening, the existing door if there is one, and the surrounding structure that takes place before manufacture begins. It is separate from the sales visit, and it is the appointment that converts your order into the precise specification the factory will build to.
The survey usually happens within a week or two of order confirmation, often before any deposit is invoiced for manufacture. It is carried out by an installer or technical surveyor, not by a salesperson, and the purpose is to confirm that the door you have ordered will fit, perform and comply correctly in your specific opening. The brochure dimensions are nominal; the survey produces the actual numbers the factory needs.
The survey is not a quote, although it can adjust the quote in either direction. It is not a sales visit, although it may identify upgrades worth considering. It is the moment where the project becomes real, and the quality of the survey is one of the strongest signals of the quality of the installer.
Why the survey matters before installation
The case for taking the survey seriously becomes obvious when you look at what gets caught at this stage versus what gets caught on installation day.
Fit is the most direct concern. UK openings, particularly on properties more than thirty years old, are rarely perfectly square. A frame ordered to nominal dimensions and shipped to an out-of-square opening will not seal properly, the locking points will not engage cleanly, and the homeowner ends up with draughts and security concerns within months. The survey catches these issues and adjusts the manufacturing dimensions accordingly.
Compliance is the second concern. Replacement external doors fall under Approved Document L of the Building Regulations, which sets minimum thermal performance for any door fitted as part of a replacement. The surveyor confirms that the specification meets these requirements, including U-values and any applicable safety glazing rules. A registered FENSA or CERTASS installer self-certifies the work and provides a certificate that conveyancers ask for when you sell.
Structural integrity is the third. The surveyor checks the lintel above the opening, the condition of the timber sub-frame, the brick reveals, the threshold and the floor level. Issues at any of these points can mean the difference between a one-day installation and a two-day project with structural work involved.
Lead time and quote accuracy are the fourth. The survey confirms the manufacturing dimensions, identifies any non-standard requirements, and validates the quote. A door surveyed honestly is a door that arrives correctly and a price that does not change at the last minute.
What happens during the visit
A door survey on a typical UK home takes between thirty minutes and an hour, depending on the complexity of the opening and the property. Here is what the surveyor will actually do during that time.
Arrival and initial discussion
The surveyor will introduce themselves, confirm the order details, and walk through your priorities. This is the moment to mention anything that might affect the installation: alarm sensors on the existing door, low ceilings or stairs that affect access, parking restrictions on the day, and any concerns you have noticed about the existing door (draughts, sticking, daylight gaps).
External inspection
The surveyor walks around the door externally, looking at the brickwork, render or cladding around the opening, the existing threshold, the path or step in front of the door, and the overall weatherproofing detail. They will note any cracks in the surrounding masonry, any signs of damp at the base of the frame, and any rendering or pointing that may need attention before or during installation.
Internal inspection
Inside, the surveyor checks the plaster reveals around the opening, the floor level on both sides of the threshold, the skirting boards, and any architrave or trim around the existing frame. They will look at how the existing frame is fixed to the masonry, whether expanding foam, mechanical fixings or older sealants have been used, and what condition the surrounding plaster is in.
Measurements
The measurements are the heart of the survey. The surveyor takes brick-to-brick (the actual structural opening), as well as frame-to-frame on the existing installation. They measure the width at the top, middle and bottom, and the height at the left, middle and right. The smallest measurement at each axis is what the new frame will be sized to, with appropriate allowances for fitting tolerances.
Diagonal measurements check whether the opening is square. A difference of more than a few millimetres between the two diagonals indicates an out-of-square opening, which the surveyor records so the new frame can be packed and shimmed appropriately during fitting.
The threshold is measured separately, including the height of the existing threshold, the floor levels on both sides, and any drainage requirements. For low-threshold installations, the surveyor needs to confirm that the floor level inside is suitable and that water cannot run under the door in heavy rain.
Frame and structural checks
The surveyor inspects the existing timber sub-frame for rot, the lintel above the opening for any sag, and the brick reveals for spalling or damage. On Victorian, Edwardian and 1930s properties, the original timber sub-frame is often hidden behind decades of paint and filler, and surveyors with experience can usually identify whether replacement is likely to be needed by tapping and probing carefully.
Door specification confirmation
The surveyor confirms the slab specification, the colour, the glazing details, the hardware specification and the lock and cylinder rating. This is the moment to ask any final questions about the product, including whether laminated rather than only toughened glass is included on glazed panels, what cylinder rating is fitted (TS 007 three-star or Sold Secure SS 312 Diamond), and whether the multipoint lock is from a recognised manufacturer.
Photos and notes
Most surveyors photograph the opening, the existing door, the surrounding masonry and any notable features. These photos go into the manufacturing file and are referenced if any questions arise during the build or at fitting. They also protect both parties if there is a discussion later about the condition of the opening before work began.
Sign-off and next steps
At the end of the visit, the surveyor will confirm the manufacturing dimensions, any adjustments to the original quote, the lead time from order to fitting, and the next steps. You should receive an updated specification or revised quote within a few days if anything has changed.
What the surveyor is checking behind the scenes
Beyond the obvious measurements, an experienced surveyor is making a series of judgement calls about the opening that affect both the installation and the long-term performance of the door. Most homeowners do not see this part of the visit explicitly, but it is where the value of a good surveyor really sits.
Squareness is the foundation. The surveyor is mentally building the new frame into the opening as they measure, identifying where shims will need to go, how the frame will sit relative to the existing plaster line, and where any making-good will be needed.
Damp is a recurring concern. Water staining, salt deposits or soft plaster around the existing frame are signs that water has been getting in for some time. A new frame will not solve an underlying damp problem, and the surveyor needs to flag this before the homeowner discovers it on installation day.
Lintels matter, particularly on older properties where the original lintel may have sagged or settled. A bowed top to the opening is a sign that the lintel needs attention before the new frame goes in. On listed properties, this conversation may also involve a conservation officer or structural engineer.
Services around the opening are easy to overlook. Alarm contacts, doorbell wiring, satellite or telephone cables, and external lighting all need to be considered. The surveyor identifies any services that need to be relocated or accommodated, and this is far easier to arrange before installation day than during it.
Drainage at the threshold matters more than most homeowners appreciate. The surveyor checks the path or step level relative to the existing threshold, looks for any signs of water pooling, and considers how rainwater will run off after the new threshold is fitted. Low aluminium thresholds are popular for accessibility, but they only work when the surrounding drainage is detailed correctly.
Access for the installation team is the final practical check. The surveyor confirms how the new door will arrive at the property, where the van will park, and whether the route from van to opening is clear. On flats, terraces with rear access only, or properties with restricted parking, this is worth flagging early.
Questions the surveyor may ask you
The conversation during a survey is not just one-way. Expect the surveyor to ask a series of questions that affect the final specification. Being prepared makes the visit more efficient.
How will you use the door? Daily access for a busy family, occasional access from a side entrance, or main front door for a property where appearance matters most? Each affects the recommended specification.
What direction does the door need to swing? Inward or outward, hinged on the left or the right? On replacement projects this is usually obvious, but on new openings or where you are reconfiguring the entrance, it is a deliberate decision.
What colour and finish? If you have selected a standard colour, the surveyor confirms it. If you have ordered a bespoke colour or RAL match, they confirm the exact reference. For composite doors, foiled finishes, painted finishes and through-coloured options have different properties worth understanding.
What hardware finish? Brass, polished chrome, brushed steel, antique bronze, matte black or pewter? The surveyor confirms the choices match the rest of the specification and that the finishes coordinate with the door colour.
What are your priorities? Security, thermal performance, noise reduction, mobility access, kerb appeal? The surveyor uses your answers to confirm that the specification matches your priorities, and may suggest upgrades that align better with what matters to you.
Are there pets, small children or mobility considerations? These affect the recommended threshold detail, the type of letterplate restrictor, and whether additional safety features are worth considering.
What can change after the survey
The honest answer is that the survey can change several things, and this is one of the reasons the survey matters. A surveyor who does not adjust anything from the original quote is rare; a surveyor who never adjusts anything is one to be cautious of, because it suggests the original quote may have skipped detail.
Manufacturing dimensions are the most common adjustment. The exact size sent to the factory is based on the survey, not the quote, and small adjustments are normal.
Pricing can change in either direction. If the survey reveals additional work needed (rotten sub-frame, lintel issues, brick repairs, or upgraded threshold detail), the price typically increases. Reputable installers walk you through any changes before invoicing, with a written confirmation of what is being adjusted and why.
Installation method may change. A standard one-day fit may extend to a day and a half or two days if structural work is needed. Conversely, a job initially quoted for two days may shrink if the survey confirms the opening is straightforward.
Lead time from order to fitting is confirmed at the survey stage. Standard composite doors typically run four to eight weeks; bespoke timber, aluminium with custom RAL finishes, and non-standard sizes can run ten to twelve weeks or longer.
UK regulations and certification
The survey is also where compliance gets confirmed. Three areas are worth being aware of.
Approved Document L of the Building Regulations sets the minimum thermal performance for any replacement door. The current edition incorporates the 2023 amendments and applies to dwellings in England. The limiting whole-door U-value for replacement windows and doors in existing dwellings is 1.6 W/m²K. Modern compliant doors typically perform comfortably better. The surveyor confirms the specified door meets these requirements.
Safety glazing rules apply to any glass within reach of the door at low level. Glazing within 300mm of the door, or below 1500mm from floor level, must be toughened or laminated safety glass. For security on glazed door panels, laminated glass is the better specification because it holds together when broken.
Certification is handled by FENSA or CERTASS through registered installers under the Competent Person Scheme. A registered installer self-certifies the work and provides a certificate confirming Building Regulations compliance, usually within four to six weeks of installation. FENSA covers replacement windows, roof windows, roof lights and doors in existing dwellings under 18 metres in height. The certificate is what conveyancers ask for when you sell. Without it, buyers can demand a retrospective Building Control inspection, which is costly and avoidable.
Listed buildings and conservation areas have additional considerations. Listed building consent is usually required for any change to a door on a listed property, and conservation area planning may restrict the choice of replacement materials and styles. If your property falls into either category, mention this at the survey stage so the surveyor can confirm the specification meets the planning requirements.
How to prepare for a door survey
The visit goes more smoothly with a small amount of preparation. None of this is essential, but each step makes the survey more efficient and the result more accurate.
Clear access to the door on both sides. Move furniture, rugs and storage away from the existing door so the surveyor can measure cleanly and inspect the surrounding plaster. Outside, clear plant pots, bins and any seasonal clutter from the immediate area around the threshold.
Know your priorities before the visit. Have a clear sense of whether security, thermal performance, kerb appeal, mobility access or something else matters most to you. The surveyor will ask, and a clear answer helps them confirm the specification is right.
Mention any known issues. If you have noticed draughts, cracking, damp staining, sticking or visible movement around the existing door, point it out at the start of the visit. The surveyor will look anyway, but flagging it directly saves time and ensures nothing is missed.
Have any renovation plans to hand. If the door is part of a wider renovation (a kitchen extension, a hallway redecoration, a porch addition), share the plans with the surveyor. Coordinating timing and specification with related work avoids problems later.
Confirm parking and access for the installation day. If your property has restricted parking or limited access, mention it at the survey so the installer can plan accordingly. Suspended bays, neighbour cooperation and tight access routes are far easier to arrange in advance.
Have your home documentation accessible. If you have a FENSA or CERTASS certificate from a previous installation, or any planning correspondence relating to the property, having it to hand can save time.
Examples by property type
Surveys vary considerably depending on the property. Here are the situations we see most often, with the practical considerations for each.
New build with an unfinished floor level
The property is recently completed, but the final floor finish (tile, wood, vinyl) has not yet been installed. The surveyor needs to confirm the eventual floor level so the threshold detail is correct. Installing before final flooring can mean the threshold sits too high or too low once the floor is finished. The right answer is usually to install the door after final flooring, or to confirm exact floor levels with the contractor before manufacture.
Period home with uneven brickwork
Victorian, Edwardian and 1930s properties rarely have square openings. The surveyor takes multiple measurements at different points and checks diagonals carefully. The new frame will be sized to the smallest dimensions and packed with shims during fitting. Period homes also often have rotten timber sub-frames hidden behind paint, which the surveyor flags so the homeowner is not surprised on installation day.
Terraced house with rear-access only
Access for the new door and removal of the old one needs careful planning. The surveyor confirms the route, checks for any obstructions, and notes where the van can park. On terraces with shared rear access, neighbours may need to be informed in advance. Larger composite doors and aluminium systems can be heavy and awkward to manoeuvre through narrow access routes.
Renovation where the opening is changing
The project involves widening the doorway, moving the entrance, or replacing a window with a door. The survey is more involved, often coordinating with a builder or structural engineer. The surveyor confirms when the opening will be ready for the new frame, what structural work is needed, and how the timing aligns with the wider project.
Listed building or conservation area
The surveyor confirms the specification meets any planning consent or listed building consent already obtained. Engineered timber in a sympathetic style is usually the required material. The survey may also identify period details that need to be replicated or preserved. Discuss the project with the local conservation officer before the survey if you have not already done so.
Mobility access requirement
The homeowner needs a low or level threshold for wheelchair access, walking aid use or general mobility. The surveyor confirms the floor level on both sides, the drainage at the threshold, and the suitability of a low aluminium threshold for the property. Low thresholds work well in most situations but require careful detailing to avoid water ingress in heavy rain.
What happens after the survey
Once the survey is complete and any specification adjustments are confirmed, the project moves into the manufacturing phase. The factory typically takes four to eight weeks to build a standard composite door, longer for bespoke timber, aluminium with custom finishes, or non-standard configurations.
The installer will contact you to confirm the installation date once the door is ready. Most reputable installers give at least a week’s notice and confirm the appointment a day or two beforehand.
On installation day, the team arrives, lays protective sheeting through the access route, removes the old door and frame, prepares the opening, fits the new frame plumb and square, hangs the slab, fits glazing and hardware, seals internally and externally, tests operation thoroughly, and cleans up before handover. A standard replacement on a sound opening is a half-day to one-day job.
After installation, you should receive the FENSA or CERTASS certificate by post within four to six weeks. Keep this with your home documentation. The manufacturer’s product warranty and the installer’s workmanship warranty should both be issued at handover. Most reputable installers also offer a free service call in the first year to fine-tune any minor adjustments as the door beds in.
Frequently asked questions
1. How long does a door survey take?
Typically thirty minutes to an hour for a standard front door on a UK home. More complex projects, including listed buildings, large glazed doors, sidelights, or openings being altered structurally, can take longer. The surveyor should not feel rushed; this is the appointment that determines whether the installation will be straightforward.
2. Is a door survey the same as a quote?
No. The quote is the initial pricing visit, usually carried out by a salesperson. The survey is the technical inspection, usually carried out by an installer or surveyor, that confirms the manufacturing dimensions and may adjust the original quote based on what the surveyor finds.
3. Do I need to be home for the survey?
Yes. The surveyor needs internal access to measure the opening and check the surrounding structure, and there are usually questions about the specification that need confirming. You do not need to follow the surveyor around the house, but you should be available for the discussion and sign-off.
4. Will the surveyor remove the old door?
No. The survey is a non-invasive inspection. The existing door stays in place until the day of installation. If the surveyor needs to access something behind the existing frame, they will discuss this with you and arrange it appropriately.
5. Can the price change after the survey?
Yes, in either direction. The survey may reveal additional work needed (rotten sub-frame, lintel issues, brick repairs) that increases the price, or confirm a simpler installation than originally allowed for. Reputable installers walk you through any changes in writing before invoicing.
6. What measurements are taken?
Brick-to-brick width and height at multiple points, frame-to-frame on the existing installation, diagonal measurements to check squareness, threshold height, floor levels both sides, and any sidelight or fanlight dimensions. The smallest measurement at each axis is what the new frame is sized to.
7. What happens if my doorway is not square?
This is normal on UK properties, particularly older ones. The surveyor records the discrepancy and the new frame will be sized to fit and packed with shims during installation. An out-of-square opening is rarely a problem in itself; the survey is the appointment where it gets accommodated correctly.
8. Can I change the style after the survey?
Sometimes, but it depends on how far through the order process you are. Minor changes (colour, hardware finish, glazing pattern) can often be accommodated up to a certain point. Major changes (door type, frame material, size) may require restarting the order. Discuss any changes with the installer as early as possible.
9. Do replacement doors need Building Regulations approval?
Yes. Replacement external doors are controlled fittings under the Building Regulations and must meet thermal performance, safety glazing and security standards. A registered FENSA or CERTASS installer handles certification on your behalf and provides a certificate confirming compliance.
10. Will I get a FENSA or building compliance certificate?
If your installer is registered with FENSA or CERTASS, yes, usually within four to six weeks of installation. Keep this with your home documentation; conveyancers ask for it when you sell. If your installer is not registered, the work needs to be notified to local Building Control instead, which adds time and cost.
11. What should I do before the surveyor arrives?
Clear access to the door on both sides, know your priorities, mention any known issues with the existing door, have any renovation plans to hand, and confirm parking and access. None of this is essential, but each step makes the visit more efficient.
12. What if I have a listed, period or conservation-area property?
Mention this at the survey stage. Listed building consent or conservation area approval may apply, and the specification may need adjusting to meet planning requirements. Engineered timber in a sympathetic style is usually the required material on listed properties. Discuss the project with the local conservation officer before ordering if you have not already done so.