Window replacement and brickwork

Whether you are upgrading to modern double glazing or repairing a damaged bay window, addressing the masonry ensures your new units don't suffer from damp, drafts, or structural sagging in the years to come.

What Does the Work Involve?

• Site Preparation: Protecting internal flooring and furniture with heavy-duty dust sheets and setting up external access or scaffolding if required.
• Removal: Carefully removing the existing glazing and frames to minimise damage to the surrounding brick reveals.
• Structural Assessment: Inspecting the existing lintel (the beam above the window) for signs of failure, rust, or timber rot.
• Brickwork Repair: Replacing "spalled" or blown bricks and repointing the mortar joints around the opening to ensure a weather-tight seal.
• Lintel Installation: If the original support is inadequate, a new steel or concrete lintel is installed to support the weight of the masonry above.
• Window Fitting: Securing the new unit, fitting the external cill, and applying expanding foam or specialist tape for airtightness.
• Finishing: Applying external silicone sealant and making good the internal plasterwork, window boards, and decorative trim.

Typical Costs

Prices vary significantly based on the frame material (uPVC, Timber, or Aluminium) and the extent of the masonry work required. Structural changes, such as widening an opening, will always attract higher labour costs due to the need for temporary supports (Acrow props).

Note: Regional variations apply, with London and the South East typically seeing 15-20% higher labour rates than the national average.

How Long Does It Take?

• Straightforward Replacement: 3–5 hours per window for a standard uPVC unit with no structural issues.
• Window + Lintel Replacement: 1–1.5 days per window to allow for mortar setting and structural safety.
• Full House (8-10 windows): 3–5 days for a standard crew, including minor brickwork touch-ups.
• Structural Alterations: 2–3 days per opening if widening or lowering the brickwork is required.

DIY or Professional?

While a confident DIYer can fit a window, it is rarely recommended for three reasons: certification, structural risk, and warranty. Professional installers provide FENSA or Certass certification, which proves the work meets UK Building Regulations—essential when selling your home.

Replacing a window without checking the lintel can lead to cracked masonry or even partial wall collapse. Always seek professional advice if you notice "stepping" cracks in the bricks above your current window.

Choosing the Right Tradesperson

• Check Accreditations: Look for FENSA, Certass, or Assure registration to ensure the work is self-certified for Building Regs.
• Brickwork Expertise: If structural work is needed, ensure they have a qualified bricklayer or can demonstrate masonry experience.
• Insurance: Verify they hold Public Liability insurance (minimum £2 million).
• Questions to Ask:
  • Do you provide an insurance-backed guarantee?
  • Will you match the existing mortar colour for the brick repairs?
  • Is the disposal of the old frames and rubble included in the quote?
  • Will you be installing a new lintel or using the existing one?

UK Regulations

• Part L (Conservation of Fuel and Power): Replacement windows must meet specific U-values (thermal efficiency standards).
• Part F (Ventilation): Most new windows must include trickle vents to prevent condensation and mould.
• Part K (Protection from Falling): Toughened safety glass is mandatory for windows within 800mm of the floor.
• FENSA/Certass: You must receive a compliance certificate within 30 days of the job being completed.

Common Problems

• Mismatched Mortar: Using modern cement on old lime-mortar bricks can cause the bricks to crumble and looks unsightly.
• Cold Bridging: Failing to insulate the cavity or reveal properly, leading to a "cold spot" where mould will grow internally.
• Failed Lintels: Installing a heavy new window into an opening where the old timber lintel has rotted, causing the brickwork to sag.
• Poor Drainage: Incorrectly fitted cills that allow water to run back into the brickwork rather than away from the house.

Frequently Asked Questions

Do I need planning permission to change my windows?

In most cases, no, as it falls under Permitted Development. However, if you live in a Conservation Area or a Listed Building, you will almost certainly need consent, especially if changing the material or style.

Why do I have cracks in the bricks above my window?

This usually indicates lintel failure. Over time, timber lintels rot or steel lintels corrode and expand. These should be replaced during the window installation to prevent further structural damage.

Is a FENSA certificate really necessary?

Yes. When you sell your house, the buyer's solicitor will ask for it. Without one, you may have to pay for an indemnity insurance policy or an expensive retrospective inspection by Building Control.

Can you match the bricks if you widen my window?

Professional brick-matching services can find a close match for most UK bricks. If the house is very old, your tradesperson may suggest "toothing in" reclaimed bricks for a seamless finish.

What are trickle vents and do I need them?

Trickle vents are small openings in the frame that allow for background ventilation. Under current UK Building Regulations, they are mandatory for most replacements to ensure adequate airflow and prevent dampness.