Windows & External Doors

Per EN 14351-1, all windows and external pedestrian doors placed on the EU market must carry CE marking with a Declaration of Performance (DoP). The DoP must declare performance values for essential characteristics including air permeability (EN 12207), watertightness (EN 12208), resistance to wind load (EN 12210), thermal transmittance, and acoustic performance. Products must be tested by a notified body where required.

1. Verify CE marking is present on the product or accompanying documentation per EN 14351-1

2. Obtain and review the Declaration of Performance for each product type

3. Confirm declared performance values meet project specification requirements

4. Cross-reference product labels or markings with delivery documentation

5. Check that any fire-rated doorsets carry additional certification per EN 16034

- CE marking documentation missing or not available on site for verification

- Declared performance values do not meet the project specification requirements

- Products substituted without re-verification of performance declarations

- Fire-rated doors supplied without EN 16034 classification documentation

Per EN 14351-1 and manufacturer's installation instructions, window and door frames must be installed plumb, level, and square within specified building tolerances. Fixings must be suitable for the substrate and spaced per manufacturer's requirements. Frames must be shimmed to prevent distortion and allow thermal movement. Structural openings must be within tolerance to avoid excessive packing or gaps.

1. Check frames are plumb (max 2 mm per metre) and level using a spirit level

2. Verify fixing type is appropriate for the wall substrate (masonry, timber frame, steel)

3. Confirm fixing spacing meets manufacturer's requirements (typically 150 mm from corners, 600–800 mm centres)

4. Check shims are correctly positioned and do not distort the frame profile

5. Verify operating clearances allow smooth opening and closing of all sashes and leaves

- Frames racked or twisted due to inadequate shimming, causing operation difficulties

- Fixings too widely spaced or incorrect type for the substrate material

- Frames fixed too tightly without allowance for thermal expansion

- Opening tolerances exceeded, resulting in excessive gap filling

- Cavity closers missing or incorrectly installed around frames

Per EN ISO 10077-1, the overall thermal transmittance (Uw) of the window must be calculated considering the frame (Uf), glazing (Ug), and linear thermal transmittance at the glass edge (Ψg). Thermal breaks in aluminium frames are essential to achieve required Uw values. The installed Uw must meet the project specification and national EPBD implementation requirements for the climate zone.

1. Verify the declared Uw value from the product DoP meets project specification requirements

2. For aluminium frames, confirm thermal break profiles are continuous and undamaged

3. Check glazing spacer bars — warm-edge spacers reduce Ψg and improve overall Uw

4. Use thermal imaging to identify thermal bridges at frame-to-wall junctions after installation

5. Confirm insulation is present around the frame perimeter to prevent cold bridging

- Uw value declared by manufacturer not achieved due to incorrect glazing unit specification

- Thermal breaks in aluminium frames damaged during handling or installation

- Cold bridging at frame perimeter due to missing insulation between frame and wall

- Warm-edge spacers specified but standard aluminium spacers installed instead

Per EN 12207, windows must achieve the declared air permeability class (Class 3 minimum recommended for most applications, Class 4 for exposed locations). Per EN 12208, watertightness classification must suit the building exposure — typically Class 5A to 9A for most applications. Weather seals must be continuous, correctly profiled, and properly seated in their grooves.

1. Review the declared air permeability class per EN 12207 and confirm it meets project requirements

2. Verify the declared watertightness class per EN 12208 against the building exposure conditions

3. Inspect weather seals on all opening lights — check for continuity, correct seating, and compression

4. Check drainage slots in outer frames are clear and correctly positioned to drain water

5. Use a smoke pencil or anemometer around opening lights to detect air leakage paths

- Weather seals displaced from grooves or incorrectly fitted, reducing air tightness class

- Drainage slots blocked by sealant or debris, causing water to back up into the frame

- Air permeability class too low for exposed locations, leading to excessive draughts

- Gaskets compressed beyond recovery at corner joints, creating leakage points

Per EN 572, basic glass products must meet dimensional and quality requirements. Insulating glass units (IGUs) must comply with EN 1279 series for durability, moisture penetration, and gas leakage. Safety glazing in critical locations must meet EN 12600 impact classification (minimum 1C1 for doors, low-level panels). Glazing must be correctly seated on setting and location blocks with appropriate clearances per EN 12488.

1. Verify safety glazing is installed in all critical locations per EN 12600 (doors, side panels, low-level glazing below 800 mm)

2. Check IGU markings confirm compliance with EN 1279 and match specification (coating type, gas fill, spacer)

3. Inspect glazing blocks — setting blocks at quarter points, location blocks correctly positioned per EN 12488

4. Verify glazing rebate drainage is clear to prevent water accumulation around the IGU edge seal

5. Check for visible defects: scratches, chips, seal failures, or condensation between panes

- Safety glazing omitted in critical locations such as doors and low-level panels

- IGU seal failures allowing moisture ingress between panes (visible as fogging)

- Glazing blocks missing or incorrectly positioned, causing glass to bear on frame

- Toughened glass with nickel sulphide inclusions causing spontaneous breakage

Per EN 15651, sealants used at window and door perimeters must be classified for their intended use (Type F for facades, Type G for glazing). Sealant classification per EN ISO 11600 must match the expected joint movement. Joints must follow the principle of inner seal (airtight) and outer seal (weathertight but vapour-permeable) to prevent interstitial condensation within the frame-to-wall junction.

1. Verify sealant products are classified per EN 15651 and EN ISO 11600 for the intended application

2. Check internal sealing is continuous and airtight (vapour-resistant tape or sealant)

3. Confirm external sealing is weathertight but allows vapour to escape (pre-compressed foam tape or vapour-permeable sealant)

4. Inspect sealant bead profile — minimum contact width of 6 mm on each substrate, correct depth-to-width ratio

5. Verify backing rod or bond-breaker tape is used to prevent three-sided adhesion in movement joints

- Same sealant used internally and externally, trapping moisture within the frame junction

- Sealant applied without primer on substrates requiring it, causing adhesion failure

- Joint dimensions outside sealant manufacturer's recommended range for the product class

- Pre-compressed foam tape not fully expanded before cladding or render is applied over it

- Three-sided adhesion in movement joints causing sealant to tear when the joint moves