# NI Building Regulations, Technical Booklet A: Structure
Technical Booklet A in Northern Ireland does the same job as structural sections elsewhere: it's there to make sure the building actually stands up and copes with the loads it will see.
1. What it covers
Technical Booklet A deals with:
- Foundations and ground · loads, bearing capacity, settlement.
- Load-bearing walls, columns, beams · stability and strength.
- Floors and roofs · structural capacity, deflection, loadings.
- Stability against wind and other lateral loads.
- Disproportionate collapse for certain buildings (bigger or taller).
It gives you the functional requirements (what the structure must achieve) and accepted ways of meeting them, typically by following specific British Standards or Eurocodes and standard details.
If you follow the methods and codes in Booklet A, Building Control will usually accept that you've met the structural requirements.
2. Design vs build, who does what
The designer/engineer
- Picks the right structural codes (Eurocodes or BS) and NI load data.
- Designs foundations, walls, beams, lintels, floors, roofs to those rules.
- Prepares drawings, calculations, and maybe certification.
Council Building Control
- Checks the structural design against Technical Booklet A when you apply.
- May query details or ask for additional calcs.
You, the contractor
- Build exactly what's on the approved structural drawings and spec.
- Don't change sizes, spans, bearings, or layouts unless the engineer and Building Control sign it off.
If you freelance the structure on site "because that's how we usually do it in England," you're stepping outside NI's approved design.
3. On-site structural hot spots
Foundations
Follow the depths and widths on the drawings. If the ground you find isn't what the design expected, stop and get new instructions · don't just deepen or shallow them on feel.
Lintels and beams
Fit exactly the lintel/beam type, size, and bearing shown. Use the correct padstones and spreaders, don't substitute random blocks.
Load-bearing walls
Don't remove or thin load-bearing walls unless it's clearly included in the design with replacement beams/lintels. Make sure blockwork/masonry density and type match the spec.
Floors and roofs
Joist size, spacing and orientation are not suggestions, they're designed that way. Prefab trusses must be installed, braced and fixed as per the manufacturer's layout and details.
Ties, straps and bracing
Wall ties, restraint straps and bracing are there to hold the shell together under wind and other loads. Miss them or move them and you're well outside the comfort zone of Booklet A.
4. Disproportionate collapse
For some NI buildings, especially multi-storey or certain uses, Technical Booklet A brings in measures against disproportionate collapse. That can mean:
- Tying floors and walls together more strongly.
- Using specific detailing or structural continuity.
If you're on that kind of job, expect heavier or "belt and braces" structural details. Stick to them: don't lighten or remove "spare" steel or fixings.
5. How this plays with NI Building Control
Because everything runs through district council Building Control:
- Your structural design is checked against Booklet A at plan-check stage.
- Inspections may focus heavily on structure: foundations, frames, lintels, floors, roofs.
- At sign-off, they're assuming what's in the ground and walls matches what was approved.
Before you start
- Get the approved Building Control drawings and structural calcs.
- Confirm the application has been approved, not just submitted.
During the build
- Flag anything structural that doesn't match site conditions.
- Don't make un-designed alterations · kick them back to designer + Building Control.
Before completion
- Check structure against the drawings, especially any changes that crept in.
- Make sure mid-job structural changes have formal approval on record.
Your mental switch for NI
"I'm under the NI Building Regulations Order and Technical Booklets, not English or Scottish regs. Structure = Technical Booklet A + what council Building Control has approved. Any 'standard details' from England or Scotland get run past the NI designer/BC before I use them."
What to do next
- Read: Working in Northern Ireland · building regulations overview
- Read: NI Building Regulations · Technical Booklet B: Materials and workmanship
Sources
- Building Regulations (Northern Ireland) Order 1979 · primary legislation.
- Technical Booklet D (NI) · Structure (note: NI uses different letter assignments).
- Eurocodes / British Standards · structural design codes referenced in NI guidance.
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