Before windows are replaced, it is essential to check the condition of the lintels to assess their structural stability.
If there are cracks running from a window’s top corners, often at 45°, the likelihood is that the lintel has failed.
Sometimes the lintel is simply weak and needs reinforcing to ensure there is no movement and in some cases there is no lintel at all and the masonry has simply been supported by the existing window frame. In this situation a new lintel must be installed or created.
Traditionally, the brickwork above a window would be removed and a new concrete lintel or steel angle installed. This is time consuming, expensive and, with three new courses of brickwork, visually unappealing. It is also extremely disruptive for the residents as it involves having mechanical props both internally and externally to support the masonry during lintel installation.
The Helifix Helibeam system overcomes all these difficulties by using the existing masonry. It is quick, simple, reliable, economical and non-disruptive. Mortar beds are channelled-out at two levels above each window and pairs of stainless steel HeliBars are bonded into the slots with HeliBond cementitious grout. A deep masonry beam is formed above the window which supports the masonry and spreads the structural loads. Generally, DryFix remedial ties or grouted CemTies are then installed vertically up through the brickwork and into the new masonry beam to secure the existing lintel. No mechanical supports are required and the existing window frame can be removed and replaced without fear of the masonry moving.
Runnymede Borough Council, Surrey
Following a window replacement programme four years earlier, these calcium silicate brick council houses were suffering from masonry shrinkage and cracking and sagging of the lintels above the windows.
The original plan was to undertake comprehensive re-pointing and install remedial movement joints plus a full lintel replacement programme. This would have involved the removal and rebuild of all cracked brickwork and the installation of stainless steel angles above all windows. This option would have been very disruptive to occupants and the building fabric, leaving a visually undesirable result, and had an average anticipated cost of £20,000 per house.
The Helifix method required no taking down and rebuilding or steel lintels, was much quicker and caused minimal disruption. Furthermore, the average cost was £3,000 on 87 houses – a saving of nearly £1.5m. Indemnified warranties were provided to the client.
London Borough of Haringey
At Trulock Court, a 10 storey ‘Y’ shaped residential tower block, the masonry above each opening was only supported by the existing load bearing metal windows and there was also a serious lack of wall ties.
The Helifix system avoided the difficulty and expense of using temporary mechanical supports and the installation of new concrete lintels. It was much quicker and more economical, enabling the window replacement and remedial wall tie programmes to be completed in just three weeks. Also, it had no effect on the building’s appearance.
Norwich City Council
Before beginning a major window replacement programme on numerous council properties, surveys indicated that masonry above the soldier course header bricks could move once the existing frames were removed, making installation of the new frames extremely difficult. major failures had been experienced before commencing installation of the Helibeam system from Helifix.
To ensure that this did not happen, and to avoid having to use disruptive and expensive mechanical supports, the council specified the Helifix system of lintel reinforcement.
Furthermore, it was cost-effective, caused minimal disruption and the work was covered by a Helifix warranty for the products and installation, undertaken by an Approved Installer, as well as third party insurance with the Consumer Protection Association.
London Borough of Barnet
A number of 1930’s council homes, due for replacement windows, had 45° cracks running from the window’s top corners and were found to have no existing lintels. A rapid and reliable means of reinforcing the masonry was required to allow the programme to remain on schedule.
The Helifix system was chosen as it was fast, economical and non-disruptive, enabling all tenants to remain in their homes while the work was carried out.
Sanctuary Housing, Scarborough
Many of these housing association properties, which were due for window replacement, had inadequate outer leaf support above the windows. Additional reinforcement was required to avoid any movement of the masonry above the openings once the existing window frames had been removed.
Using a combination of grouted HeliBars, DryFix and CemTies, new masonry beams were created over each window and the soldier course lintel brickwork secured into the beams above. Work was completed quickly and efficiently and the buildings left visually unaltered.