When an opening needs a steel girder
Open out the whole back of a house, or remove a corner so two openings meet, and a single beam is often no longer enough. That is when the engineer's drawing starts showing a girder: a heavier beam whose job is to carry other beams. Here is what that means for your project.
What a girder actually is
A girder is not a different kind of steel. It is a beam, usually a universal beam or column section, that carries other beams instead of carrying the floor or roof directly. Because it collects the load from several beams, it is bigger and heavier than everything around it.
In a typical Dublin rear extension, the girder runs along the line of the old back wall. The beams that span across the new opening land on it, and the girder passes all of that load down to its own supports at each end.
Where the load goes
A girder concentrates a lot of weight onto two small points, and those points need proper support. Sometimes that is a steel post, sometimes a beefed up section of wall with padstones, and occasionally a new foundation if the existing ground cannot take it.
This is the part of the design that decides whether the job is straightforward or involved. Removing a corner of a house means the girder meets another beam at the corner post, and that post carries load from both directions. It is very doable, but it has to be engineered, not guessed.
Fabrication and connections
We fabricate girders with the connection points for the incoming beams already welded or drilled in: cleats, end plates or seated connections exactly where the engineer's drawing puts them. The beams that land on the girder are fabricated in the same job so the whole arrangement fits together on site.
Everything leaves the workshop CE marked under EN 1090 EXC3 with its declaration of performance, which is the paperwork your building control or certifier will ask for.
Getting it into the house
Girders are heavy. A section carrying a full rear opening on a two storey house can run to half a tonne or more, which is beyond a manual lift. Plan on a crane or a telehandler, and tell us early about access: over the house from the front road is common on Dublin terraces and needs a proper lift plan.
The girder usually goes in before the beams it carries, propped until the supports and connections are complete. Your builder and engineer sequence this; our job is to deliver steel that fits the first time, marked so everyone knows which end is which.
What to send us
The engineer's drawing is the starting point: section sizes, lengths, connection details and the support arrangement at each end. A photograph of the structural drawing page is enough for a budget price, and the full drawing gets you a firm quote.
If you are earlier in the process and wondering whether your planned opening needs a girder at all, that is a question for your engineer, but we are happy to talk through what similar jobs have involved.
Want this priced for your own job? Send us your drawings or a photo and we will come back with a fixed price, usually within one working day.
Common questions
Need this done properly? Talk to the workshop.
Send us drawings, a sketch or a site photo. We come back with a fixed price and a firm lead time, usually within one working day.