Public House have
been experimenting with timber truss designs for a number of years now. They're
a very engineering way to span long
distances or support heavy loads. By taking a typical beam, distributing the
area away from each other with connecting diagonal members, the structural
capacity of the same amount of material increases exponentially. Almost all
lightweight, long-span structures you see are trusses - bridges, stadiums,
concert halls.
Kala Festival - Unit 38 Architects / Public house - Image: Sandra Nagel / Sienna Lorraine
For obvious reasons,
they're also difficult to introduce into our (slightly smaller) projects:
trusses require depth in order to function; the triangles and diagonals that
make up the truss are often tricky to accommodate into architecture; and they
need to be assembled from lots of individual elements.
Kala Festival - Unit 38 Architects / Public house - Image: Sandra Nagel / Sienna Lorraine
But often, trusses
could make a big difference when we're asked to span long distances or transfer
heavy building loads over a new open space below. Normally, we use a heavy
steel beam or a glulam timber beam to carry the heavy load within an efficient
structural depth, to maximise ceiling height. The drawback of this approach is
the weight of the structural beam and associated material and manufacturing
cost. Since deep down we are engineers, we've always been chewing on ways to
replace these heavy, expensive and highly engineered solutions with something
more simple and cheap.
Public House research - truss arch concert stage
So we started
investigating how to design truss systems that could be constructed from basic
raw timber sections and assembled using simple connections that kept the
overall cost below that of an equivalent steel or glulam beam.
For long spans where
a heavy steel beam or engineered glulam beam is required, using a truss
dramatically reduces the material quantities required. So much less, that where
we've developed a truss solution, we've been able to reduce material weight by
50% (vs. steel or glulam) and use only basic small raw timber sections, the
ones you can buy from your local timber merchant.
Public Works Architects / Public House - Anaerobic Digestor, 2025
But the truss
connections were the key to making this idea viable. Limiting ourselves to
cheap and readily available standard timber sections, it was important that the
connections and the carpentry to fabricate the truss were also simple (heavy
steel/glulam beams still benefit from how quickly they can be brought from the
supplier and installed on site).
With small truss
members, the connections at the nodes between the elements can require a lot of
bolts spread along the member length. Typically, custom bolted steel plates or
shoes are used. We developed a cheap and simple bolted plywood plate connection
alternative: a full-timber solution, easy to fabricate using standard CNC
machines, and the whole thing can be assembled in the workshop or on site.
Comparison study - 8.4m span roof support beam / truss (PH Research)
On projects we've
worked on, this system is a viable alternative to heavy steel beams and
engineered glulam beams. The cost is around 50% lower, the weight is around 50%
lower, its easy to assemble and lift into place.
Primary structure weight - 8.4m timber span (PH research)
Installed cost = material (beam, plate/timber stock, connectors) + manufacture (fabrication, machining, gluing) + install (transport, crane time, fixing on site). The three‑way split shown is an illustrative estimate at typical UK proportions for each build‑up, not a line‑item quote — get fabricator, timber‑frame and glulam supplier quotes before costing a real project. Ranges: steel[2–5], softwood/plywood[6,7], glulam[8–13]. (PH research)
The embodied carbon
is also 80% lower than the steel beam and 50% lower than the glulam equivalent.
As with all the design work that Public House does, it follows a careful logic
around sustainability: Do less and retain more; Use fewer materials by thinking
more and making them work harder; try to re-use materials, or standard section
sizes that can be re-used; and use materials that are not so energy-intensive.
The truss follows this logic - where the structure is required, we've developed
an innovative system that uses simple and standard-sized materials that work
hard. The embodied carbon calculations are reflective of this approach.
CO₂ basis. Process and sequestration factors for steel (S275), glulam and structural softwood (C24) are from the Inventory of Carbon and Energy (ICE) database, Circular Ecology / University of Bath [14]. (PH Research)
Kala Festival - Unit 38 / Public House
Self-build project - Public House
References| # | Source | Used for |
|---|
| 1 | PublicHouse, Structural Design Report — Anaerobic Digestor, Loughborough Junction, Rev01, 2025 | Span, load and section basis |
| 2 | SteelFlo, "Steel Fabrication Costs 2026" | Steel fabrication cost structure |
| 3 | CoreMetSteel, "UK Steel Price Forecast 2025–2026" | UK steel price trend |
| 4 | Steel Prices UK, "UK Steel Price Forecast 2026 & 2027" | UK steel price trend |
| 5 | Mixdesigncalc.com, "Steel Price Calculator" | UK structural steel £/tonne |
| 6 | BuildWiz UK, "Structural Plywood" | Plywood sheet pricing |
| 7 | Builders Merchants Direct, "Timber Prices UK 2026" | UK softwood pricing context |
| 8 | Accio.com, "Price of Glulam Beams" | Glulam £/m³ range |
| 9 | Buckland Timber, "Steel vs Glulam: Updated Costs for 2026" | Steel vs glulam cost context |
| 10 | Buckland Timber, "How Much Does a Glulam Structure Cost?" | UK glulam £/m² benchmarks |
| 11 | Lamisell, "Glulam Beams in Stock" | GL24h stock availability |
| 12 | Tailor Made Designs, "Glulam Beams" | UK glulam delivery cost |
| 13 | Robinson Manufacturing Ltd, "Glulam Beam Price Calculator" | UK glulam pricing tool |
| 14 | Circular Ecology / University of Bath, Inventory of Carbon and Energy (ICE) database | CO₂ process and sequestration factors (steel S275, timber C24, glulam) |