# PEB Anchor Bolts and Foundations Set the Programme

> On a pre-engineered building, the steel can be fabricated quickly, but it can only be erected on foundations whose anchor bolts match the PEB supplier's approved anchor bolt plan. If that plan is not frozen before casting, or the bolts are set out of position or level, erection stops and the fix is engineered rework. The foundations, not the steel, usually set the programme.

## Fast steel, slow concrete

The usual case for a pre-engineered building is speed. The frame is designed
and fabricated in a factory while the site is prepared, then bolted together
rather than cast. That is true, and it is why owners and CFOs are often
surprised when a PEB project slips at the very point the steel arrives.

The reason is simple. **Steel can only be erected on foundations whose anchor
bolts match the frame.** The bolts are cast into concrete weeks earlier, usually
by a different contractor, from a drawing issued by the PEB supplier. If that
drawing changed after the pour, or the bolts moved during it, the base plates
will not land. The crane and erection crew wait, the steel sits in the yard, and
the fix is engineered rework in concrete that has already cured.

The common misconception is that foundations are "the civil part" and steel is
"the PEB part", meeting on site as two separate scopes. **In reality the anchor
bolt is where the two scopes become one**, and the programme is decided there.

## Who owns each part of the interface

Most of the delay at this interface comes from responsibilities that nobody
wrote down. A typical split looks like this, though every contract should state
its own.

| Item | Typically provided by | What goes wrong if it is unclear |
| --- | --- | --- |
| Anchor bolt plan and column base reactions | PEB supplier | Foundations designed from a preliminary or superseded drawing |
| Foundation and pedestal design | Civil structural engineer | Pedestal too small for the bolt group or edge distances |
| Supply of anchor bolts and templates | Agreed in contract, PEB supplier or civil | Bolts arrive late, or in the wrong length or grade |
| Setting bolts, levels and protection during the pour | Civil contractor | Bolts shift, tilt or have damaged threads |
| Survey before and after concreting | Civil contractor, witnessed by erector | Errors found only when the column is lifted |
| Grouting under base plates | Agreed in contract | Grout left out, or placed before the frame is aligned |
| Acceptance before erection | PEB erector | Erection starts on bases nobody has checked |

The point for a buyer is not which column each item sits in. It is that **every
row has a named owner before the first pour.** A
[PEB buyer's guide](/guides/peb-buyers-guide-india) is a good place to see where
this sits in the wider procurement.

## Freeze the anchor bolt plan before casting

The anchor bolt plan follows the frame design. When the frame changes, the bolts
can change with it. Common late changes that move bolts or reactions:

- Bay spacing or building length adjusted to suit the site
- A crane or monorail added or upgraded
- A mezzanine introduced or relocated
- Framed openings for doors, docks or louvres added to end walls and side walls
- An extension planned, needing a different end frame

Each of these is a reasonable decision, and each is expensive once bolts are
cast. The discipline is straightforward: **bolts are cast only to an anchor bolt
plan issued for construction**, under revision control, with the civil
contractor confirming in writing which revision they are setting to. A drawing
marked preliminary or for approval is for the foundation design, not for the
pour.

The wider choice between steel and concrete frames, and how each handles
changes during design, is covered in our
[PEB versus RCC industrial building comparison](/compare/peb-vs-rcc-industrial-building).

## Templates, levels and grout pockets

The physical work of setting bolts is not complicated, but it is unforgiving.

**Templates.** A rigid template, drilled to the anchor bolt plan, holds each bolt
group in its correct pattern while concrete is placed. It must be fixed so it
cannot move or rotate, and set out from the grid lines, not from the previous
foundation.

**Projection and threads.** Each bolt must project far enough above the concrete
for levelling nuts or packing, the base plate, washers and the final nut, as the
drawing requires. Threads are protected during the pour; concrete on a thread is
removed before it hardens, not with a grinder later.

**Levels and grout gap.** The top of the pedestal is usually cast slightly below
the underside of the base plate, leaving a gap that is grouted after the frame is
aligned. The level and gap come from the PEB supplier's drawings.

**Tolerance across the building.** Accuracy matters within each bolt group and
across the whole grid, because small errors repeated along a long building stop
the last frames from fitting. Permissible deviations for erected steelwork are
set out in **IS 12843**, and the general idea of tolerances is explained under
[construction tolerances](/glossary/construction-tolerances). The tolerances that
apply to a project are those stated on its drawings and specification.

How the frame then goes up is covered on our
[PEB erection and site works](/services/peb/peb-erection-and-site-works) page.

## What a mis-set bolt actually costs

Once concrete has cured, every remedy is engineering work:

- Enlarging or slotting holes in the base plate
- Fabricating new or adapted base plates
- Installing post-fixed anchors in place of cast-in bolts
- Cutting bolts and re-embedding new ones
- Breaking out and recasting the pedestal

Anchor bolts carry tension and shear from the frame, including uplift from wind
under **IS 875 (Part 3)**, so **none of these is a site decision.** Each needs
the structural engineer's design and approval under **IS 800:2007** and
**IS 456:2000**, which takes time. Meanwhile erection of that frame waits, and
because frames go up in sequence, so may the frames after it.

The commercial cost often exceeds the physical one: an idle crane, a crew that
cannot be redeployed, steel stored and double-handled, and an argument over who
pays. That argument is short when the interface was written down and long when
it was not.

## Plan the foundations backwards from steel delivery

The programme that works starts from the date the erector needs the first
foundations, then works backwards. Before that date the foundations must be
cast, cured to the engineer's requirement, surveyed and accepted. Before they
can be cast, the anchor bolt plan must be issued for construction. Before that,
the frame design must be stable enough that the bolts will not move.

Laid out this way, two things become visible. First, **the design freeze for
the frame is a foundation milestone**, not only a steel milestone, so late
changes to bays, cranes or mezzanines have a cost that the programme shows
immediately. Second, foundations can be cast and accepted in the same order the
frames will be erected, so erection can start at one end while the civil works
finish at the other. That overlap is where much of the PEB time advantage comes
from, and it only exists if the first foundations are right.

## Common mistakes

- **Casting to a preliminary anchor bolt plan** while the frame design is still
  changing.
- **Leaving bolt supply and setting undefined** between the civil and PEB
  contracts.
- **Setting out each foundation from the last one** instead of from the grid,
  so errors accumulate.
- **Templates not fixed firmly**, so bolts move when concrete is vibrated.
- **No survey after the pour**, leaving errors to be found by the erector.
- **Assuming foundations are ready by date** rather than by test results.
- **Grouting before alignment**, locking a frame in the wrong position.

## What to ask before the first foundation is cast

- Is the anchor bolt plan issued for construction, and which revision is the
  civil contractor using?
- Are any frame changes still possible, and what would they move?
- Who supplies the bolts and templates, and who sets and surveys them?
- What tolerances apply, and where are they written?
- What concrete strength must be reached before erection, and how will it be
  confirmed?
- Who accepts the foundations on behalf of the erector, and on what record?
- Who designs and approves any remedy if a bolt is out?

## Standards referenced

Steel design and construction under **IS 800:2007**; concrete under
**IS 456:2000**; wind loads under **IS 875 (Part 3)**; foundation bolts under
**IS 5624**; and tolerances for erection of steel structures under **IS 12843**.
Bolt sizes, grades, embedment, edge distances, tolerances, curing requirements
and any remedy for a mis-set bolt must be established by the project's
structural engineer and the PEB supplier's design.

## Frequently asked questions

### What is an anchor bolt plan?

It is the PEB supplier's drawing that shows the position, grouping, projection and orientation of the bolts at every column base, usually with the column reactions the foundations must be designed for. The civil engineer designs the foundations from it and the civil contractor sets the bolts to it. It is the single document that connects the steel design to the concrete.

### Can foundation work start before the PEB design is final?

Excavation and some preparatory work can, but bolts should not be cast in until the anchor bolt plan is issued for construction. If the frame design changes afterwards, for example bay spacing, a crane, a mezzanine or a framed opening, the base reactions and bolt layout can change with it. Casting to a preliminary drawing is a common cause of rework.

### Who is responsible if the bolts are in the wrong place?

Whoever the contracts make responsible for setting them, which is why the interface needs to be written down. Typically the PEB supplier is responsible for the anchor bolt plan, the civil contractor for setting the bolts to it, and the erector for checking them before erection. If those responsibilities are not stated, a mis-set bolt becomes a dispute as well as a delay.

### How are mis-set anchor bolts fixed?

Depending on the error, by modifying the base plate holes, adding plates, installing post-fixed anchors, cutting and re-embedding bolts, or in serious cases breaking out and recasting the pedestal. Anchor bolts carry tension and shear from the frame, so every one of these remedies needs the structural engineer's design and approval. None is quick, and erection of that frame waits until it is done.

### How long must foundations cure before steel is erected?

Long enough for the concrete to reach the strength the structural engineer requires before the column bases are loaded and the bolts tightened. That depends on the mix, the weather and the curing, and should be confirmed by test results rather than a calendar assumption. The requirement belongs in the specification and the erection method statement.

### What should be checked before the erection crew arrives?

A survey of every bolt group against the anchor bolt plan: position, spacing, projection, level of the pedestal top and alignment along the grid lines. The results should be recorded and accepted by the erector before steel is delivered. Finding a problem with the crane on site costs far more than finding it a fortnight earlier.

## Sources

- [IS 800:2007](https://standards.bis.gov.in/website/published-standards/department-wise) — General construction in steel - code of practice
- [IS 456:2000](https://standards.bis.gov.in/website/published-standards/department-wise) — Plain and reinforced concrete - code of practice
- [IS 875 (Part 3)](https://standards.bis.gov.in/website/published-standards/department-wise) — Wind loads on buildings and structures
- [IS 5624](https://standards.bis.gov.in/website/published-standards/department-wise) — Foundation bolts - specification
- [IS 12843](https://standards.bis.gov.in/website/published-standards/department-wise) — Tolerances for erection of steel structures

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Source: https://hagerstone.com/blog/peb-anchor-bolts-foundations-set-the-programme