When are hybrid construction methods the best option to reduce costs and create the most efficient solution? In a recent article on value engineering foundations, we did mention that sometimes we look to simplify the superstructure as it may have been over-designed. This is still the case, but there are occasions when a single solution does not offer the best value for the overall build/design.
Hybrid construction is about choosing the right construction types for the right application and project. We will share some example projects with you where hybrid construction was the best choice and explain why.
When designing a building, once you are out of the ground and the foundations are complete, you are mostly free to choose your design method for the superstructure be it timber, steel or concrete frames or a modern method of construction. Although this may have a bearing on the foundations, they will have been designed around soil parameters, rather than the superstructure.
It might seem obvious, but it is often mixed-use buildings; shops and flats, garages and apartments that call for the construction type to match the application rather than a one size fits all solution. Soundproofing for residential flats will need to be different from the retail units below them, garages need different layouts and considerations to any retail or residential units above them. Again, we have written in the past about unifying designs for foundation purposes, but this is where our skill and experience allow us to find the most efficient solution for our clients and the project.
Example 1. Concrete and Steel frame
We had a project that was designed as steel frame over a car park, mixed with a timber frame structure for residential units. However, we felt it would be more efficient to use a concrete frame podium. It was a constrained site and an odd-shaped design, which didn’t suit a steel frame. The detailed designs had not been completed and we could see that a concrete frame would allow more flexibility for any changes in design, which we anticipated were likely and were eventually made. The concrete podium/frame also allowed for better fire resistance between the car park and residential flats above.
As the footprint of the building almost filled the site space for material storage and unloading was limited. The concrete podium provided a suitable place for the unloading and storage of the timber frame which otherwise would have needed a just in time delivery plan.
Example 2. Concrete podium with steel frame
This project was a five–story residential unit, which was classified as a 2B building under Building Regulations. We suggested that the ground floor was designed as a concrete podium, which can be designated as a key element. Doing this meant that everything above this level need only be designed as a 2A building (less than five floors). The efficiency of this decision meant that there are no onerous tying requirements throughout all five floors as the concrete podium protects the floors above from disproportionate collapse.
Example 3. Loadbearing masonry with timber frame extension
This project was a relatively small cantilever extension. The original building was loadbearing masonry, but we used timber frames to give us more flexibility because of the over–hang of the kitchen extension.
Example 4. Concrete slab and composite concrete slabs
In a basement project the original design used a composite concrete slab to form the lid, but this solution couldn’t achieve a warranty for waterproofing. Composite was originally chosen because of its span, price and the speed. We were able to solve the problem using a concrete slab. The strength of our consultancy is that we have extensive experience with basements and can identify the right material and construction type for the application early in the project.
Example 5. Concrete Frame with modular construction
Block A of this project of new modular housing in Rainham, London https://www.david-miller.co.uk/ov-4-modular.php was a concrete frame with modular construction.
Value engineering by SWJ Consulting
There are some good hybrid construction combinations that enable design flexibility such as masonry and timber frames. A mix of concrete frame and steel frames typically work well for taller buildings. A concrete frame core for elevator shafts and stairs give the building a stiff concrete core with a steel frame around the outside, which is lighter, quicker to build.
SWJ Consulting are used to working in the design & build environment, working under pressure to find solutions that are more efficient for contractors. We are experienced and adept at looking at designs with a fresh pair of eyes and with the contractor’s priorities in mind.
If you have a project you would like to discuss then please give a call on 01993 225 085 or mail@swjconsulting.co.uk
