February 28, 2023

Wind Load on Windows Case Study: Mawgan Porth House

Written by Rebecca Clayton

Designing Architectural Glazing with High Wind Load on Windows

Cornwall and the Southwest of the UK have some of the most stunning views in the country, with elevated plots for coastal views and direct access onto beaches or beautiful countryside. But these projects also come with some specific challenges, the main one being the weather considerations for their exposed locations.

Stone Haven in Cornwall

In 2021 the Met Office reported winds of 59mph in Berry Head which was the highest wind level recorded in the area at the time. And the strongest recorded wind speed in the UK was also recorded in Cornwall with a wind speed of 96mph measured in Gwennap Head in 1973.

To maximise the impact of the location and views in architectural building, architectural glazing is often a key part of a home design in Cornwall. But how can you ensure that the glazing designed for the building will be able to withstand the heavy wind loads on windows for the area?

IQ worked on this highly exposed replacement dwelling in Mawgan Porth which is a brilliant case study, showcasing how high wind loads on windows can be considered at all stages of the project and design. Read on below to find out how IQ approached this difficult gazing design and how our glazing systems were adapted to suit the exposed coastal location.

Wind Load on Windows in Mawgan Porth: The Beginning

IQ was contacted by the architects of this replacement Beach House dwelling in Mawgan Porth, Cornwall to provide the architectural glazing for the cliffside home. Whenever the IQ team begin to look at the glazing specification for a project, we always ask for the address. This allows us to better understand the location, topology, and any specific requirements for a project’s orientation to calculate the wind loads on windows.

On looking at the drawings and location of this Cornwall home it was clear immediately that wind loading to the windows would be a major design consideration.

The wind load on windows calculations for the North East and Southwest elevations of the house in Mawgan Porth

The wind load on windows calculations for the North West and South East elevations of the house in Mawgan Porth

The elevations of the home and the windows would be subjected to wind loadings of 2.1 to 2.9 kN/m2 as a minimum with some doors requiring a 3.4 kN/m2 loading requirement. IQ then took this into consideration when working with the architects on the specification of the slim sliding glass doors, windows and fixed frameless glass elements.

Wind Load on Windows in Mawgan Porth: The Frame Specification

When the order was placed with IQ for the glazing subcontract, we began our design works for the architectural glazing.

In order to design the glazing for the wind load to the windows, we made several adjustments to our typical glazing details.

Reinforcement bars were included within some the sliding glass door interlocks. These do not change the slim sightlines of the sliding glass doors but do provide additional strength to these interlocks. The reinforcement resides within the interlock chamber itself so that the visual appearance of the door sightlines is unchanged and still minimal. However, we can then ensure the wind load on windows is allowed for.

A reinforced interlock for sliding glass doors

In some other areas of the build, deeper interlocks were used for the sliding glass door junctions. These were used on the glass doors with large glass sizes and higher wind loads on windows. The deeper vertical interlock again, maintains the 21mm sightlines of the glass door panes but the deeper section creates additional strength to the joint.

The heaviest wind load for all elements of the project was a loading of 3.4 kN/m2 which was the glazing to the protruding double height annex, situated on the north west corner of the home.

To the ground floor of this wing, minimal windows sliding doors were used with 60mm deep vertical interlockers between the sliding glass panes on the outward facing north-western elevation. The doors where were 2.1m tall and 2.2m wide in a fixed-sliding configuration. On the mirrored face of the wing, a narrower minimal window (2.1m tall x 1.5m wide) was used with a 40mm interlock strengthened with an integrated reinforcement bar.

For each element, we ran the sliding glass door configurations (including size and wind load) through our wind loading calculation software which allows us to determine the required interlock to use.

A high wind load interlock for sliding glass doors

Due to the distance of the project from the sea, all framing was finished in a marine grade RAL PPC finish as is normal for any projects within close proximity to the coast.

Wind Load on Windows in Mawgan Porth: The Glass Specification

When designing and detailing the project, very little change was actually required to a typical glass specification (for IQ standards). As the systems and structural glazing methods we use require high specification glass as standard, the glass units used in the Mawgan Porth house were very similar in composition.

However, this might not be the case with all glaziers or glazing suppliers so if conducting a similar project be sure to check this before ordering.

No additional interlayers were required to achieve the strength of glass for the wind loadings. However, 8mm TXD glass was required for most of the highest wind load windows on the project.

A solar control coating was applied to some of the windows for solar protection.

Wind Load on Windows in Mawgan Porth: The Installation

Due to the location and the access to site, the installation and logistics management of the project had to be considered very carefully.

The glass was delivered to site on a 26 tonne Hiab which parked in layby on the main road through Mawgan Porth. The glass then had to be unloaded individually onto a transit flatbed which took the glass down the narrow lane to the site. There, it was off loaded via a telehandler and manually manoeuvred into place.

The Completed Glass Installation

While the glass installation is now complete, building is still being finished and constructed by Noble Construction. It will take a few months for the gardens to be completed and finished images of the project taken.

But so far, the build is looking very impressive and the expansive views of Mawgan Porth beach are captured brilliantly through the architectural glazing installed.

Within the cocoon of the house, you are protected from the harsh winds of Cornwall beyond, enabling the occupiers to enjoy the landscape from a protected and highly performing structure.

The successful glazing design and exacting wind load design for the windows plays a key part in the overall performance of the project. Keep an eye on our social media feeds for the fully completed images of this impressive project.