Secondary Glazing for Flats and Leaseholders

Why leaseholders can usually proceed

Most residential leases reserve the structure, the external walls and the windows to the freeholder, while the internal finishes and the airspace of the flat sit with you. Secondary glazing is fixed to the internal reveal or the architrave on the room side of the existing window, so it does not touch the primary frame, the glass or the outside face of the building. That is why it is the one glazing improvement leaseholders are commonly able to make.

Getting permission properly

Read the alterations clause in your lease before ordering. Many leases require written consent for internal alterations even when they are minor, and a short letter to the managing agent with a product specification and a note that the work is reversible normally settles it. Where the block is listed or in a conservation area, the freeholder may also need to satisfy the local authority, so allow extra time.

• Check the alterations and nuisance clauses
• Write to the managing agent with a specification
• State that fixings are reversible and internal
• Allow longer where the block is listed

The noise problem in city centre flats

Converted mills, warehouse conversions and new build apartment blocks sit close to main roads, tram lines, delivery bays and late night venues. The dominant sound is low frequency and it arrives through large single glazed or thin sealed units with hard reveals. A wide cavity of one hundred millimetres or more with acoustic laminated glass on the room side is the specification that changes how the flat feels at night.

Installation inside an occupied block

Work is carried out room side, so there is no scaffolding, no cherry picker and no external access to arrange with the managing agent. A typical one or two bedroom flat is a single day. We template on the survey visit, protect floors and lift access routes, and remove all packaging from site the same day, which is usually the condition managing agents care about most.

• No external access or scaffolding
• Single day for most flats
• Lift and communal area protection
• Waste removed the same day

Ventilation and condensation in flats

Flats are airtight and often under ventilated, so sealing a window without thinking about air movement can move condensation elsewhere. Where the primary window carried the background ventilation we fit trickle vents in the secondary head so the flat keeps its designed air path. Extract fans in the kitchen and bathroom matter more in a flat than in a house, because moisture has nowhere else to go.

What it does for value and letting

For owner occupiers the gain is comfort and quiet. For leaseholders letting the flat, a quieter bedroom is one of the few improvements tenants notice immediately, and the reduced heat loss helps the EPC without altering anything the freeholder controls. Because the system unscrews, it can be removed at the end of the lease if you are ever asked to reinstate.