The issue of joint reinforcement and wind posts is increasingly coming to the fore as more and more people are looking to create bigger, lighter spaces with large windows, and small masonry piers between.
Historically, homes have been built with masonry throughout with thicker walls and smaller windows. But as the insulation properties of windows have improved designs are including larger windows and now there is a growing trend for floor to ceiling glass and large bi-fold doors in designs.
These larger windows and doors need to be supported as do the walls they sit in and the biggest issue is the lateral loads they need to withstand from wind. When a gale, like 2018’s Beast from the East came howling in, a wall with large windows or bifold doors must resist all that load on a small pier, the small bit of masonry between the windows.
Pre the 1980s when most houses were built with masonry, internal walls as well as external walls, this wasn’t so much of a problem, but modern construction generally uses light weight partitions; timber or metal stud walls that are there to divide the space rather than give structural support. With these lightweight partitions there is nothing to give the structure lateral support.
So, we end up with designs that include enormous windows, lots of load and no lateral support. Such arrangements fall outside of the basic guidance given within Part A of The Building Regulations, which has not moved as fast as architectural design and only covers smaller/basic sizes that will comply without further assessment or calculations.
One option available to us, but which we try to avoid is the use of Wind Posts. Wind Posts come in two types ones that sit in the cavity and ones that sit in the inner leaf of the masonry. Wind Posts have significant challenges the most obvious being that they are usually very heavy and unwieldy so difficult to install safely. Depending on the type used they also need to be built around which can cause issues in the aesthetics as well as construction.
Wind Posts are made of stainless steel which gives them sufficient durability to last the life of the building. However, their use does give rise to acoustic, air tightness and thermal issues which require additional consideration and complicate the detailing of the wall.
Another issue we find with Wind Posts is that the average smaller contractor, house builder, is not used to using them as they are not common. Because designs have changed but the standards have not, builders aren’t familiar with them and can be resistant to installing them and the lack of familiarity can result in incorrect installation of the Wind Posts.
Bed Joint Reinforcement is an attractive alternative to Wind Posts. It is a fabricated steel reinforcement system that is installed within the bed joints of the wall to strengthen masonry panels without thickening the wall.
It does allow the wall panels to span further without additional lateral support without interrupting runs of blockwork, preventing the installation of cavity insulation and creating vertical joints in the internal leaf of the wall.
We use market leading software to assess the capacity of wall panels and to make the best use of the options available to us to realise our client’s vision for the project.
If you are planning an extension or alteration that involves large windows of bi-fold doors then please call us on 01993 225 085 for an initial discussion about your project.