Getting an RSJ installed in a Dublin home
Taking out a wall between a kitchen and a back room, or opening the rear of the house to an extension, almost always means a beam going in. People call it an RSJ, and whatever the correct term, the job around it follows the same pattern every time. Here is what to expect, in the order it happens.
The engineer comes first
No fabricator or builder should size your beam. A structural engineer inspects the house, works out what the wall is carrying, and produces a calculation and a drawing that names the exact section, its length, and how it sits at each end. That drawing is what we price and fabricate from.
If your builder says a beam size from experience, treat it as a guess until the engineer confirms it. A beam that is too light sags and cracks the plaster above. A beam that is too heavy costs more than it needs to and can be harder to get into the house.
What we fabricate
From the engineer's drawing we cut the beam to length, drill it, and weld on whatever the design calls for: end plates, cleats for timber joists, or a plate on top if blockwork sits directly on the beam. Where two beams meet at a corner opening, we fabricate the connection between them as part of the same job.
Everything is fabricated under EN 1090 EXC3 in our Dublin 22 workshop, so the beam leaves with its declaration of performance and CE marking. Building control will ask for that paperwork, and it is far easier to hand it over on the day than to chase it afterwards.
Padstones and bearings
A steel beam cannot just rest on a block leaf. The engineer specifies a padstone, a dense concrete block that spreads the load, and a minimum bearing length at each end. This is the detail most often got wrong on site, and the most common reason sign off is delayed.
We supply the beam with the bearing lengths marked, and your builder beds the padstones in strong mortar ahead of the lift. Getting the levels right at this stage is what makes the beam drop in cleanly.
The day of the lift
Before the old wall comes out, the floors above are held on adjustable props, usually acrows with strongboys through the wall. The wall comes down, the padstones go in, and the beam is lifted onto them. On a typical Dublin semi the beam for a rear opening is a few hundred kilograms, which is a two to four person lift or a small crane over the house for heavier sections.
Tell us about access when you order. A terrace with no side passage, a laneway too narrow for a HIAB, or overhead wires all change how we deliver, and it is far cheaper to plan around them than to discover them on the morning.
After the beam is in
Once the beam is bearing at both ends and the connections are made, the props stay in place until the mortar and any new masonry above have gained strength, usually a week or so. Your builder or engineer confirms when they come out.
The beam then gets boxed in and fire protected as part of the fit out. If the beam sits below the ceiling line, that is a design conversation for the engineer, not something to fix on site by trimming the steel.
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.