Roof Truss Replacement Cost UK: Pricing Guide

Summary

The technique and structural reasoning behind truss replacement — why trusses are engineered as a single unit, the temporary propping and bracing sequence, and the Building Control notification process — is covered in full in roof truss replacement guide. This article is the pricing companion: it assumes the reader already understands why the job needs a designed intervention rather than a field repair, and focuses purely on what it costs to actually get a damaged truss (or a small run of them) replaced, signed off, and weatherproofed.

Truss replacement pricing is dominated by three cost drivers that have little to do with the timber itself: access (scaffold or tower to reach the roof void or the external roof plane), design and sign-off (either a manufacturer's like-for-like drawing or a bespoke structural engineer's design, plus the Building Control Part A notification this always triggers), and temporary works (propping and bracing the adjacent trusses before the damaged one is touched, which is safety-critical and should never be treated as a rounding error in the quote). The replacement truss itself — even a bespoke one — is usually a modest fraction of the total job cost once these three elements are added in.

This guide breaks the job into its cost components, gives a quick reference table across single-truss, small-run, and larger structural interventions, and works through two full examples: a single like-for-like truss replacement with sound neighbours, and a small run of storm-damaged trusses needing a bespoke engineer's design.

Key Facts

• Like-for-like replacement (original drawings available) — the fastest and usually cheapest route; a truss manufacturer supplies an identical or directly equivalent replacement built to the original specification, typically 1–3 weeks lead time
• Bespoke engineer-designed replacement — required where original drawings are unavailable, where the roof is being modified as part of the replacement, or where the original design/installation is suspect; adds a structural/truss engineer's survey and design fee and typically extends the programme by 1–3 weeks over a like-for-like route (see structural engineer for when an engineer is required and typical fee bands)
• Truss supply cost (single domestic truss, standard Fink, like-for-like) — typically £150–£450 depending on span and complexity; wider-span or attic/hip trusses cost more
• Bespoke replacement truss (engineer-designed, one-off) — typically £300–£800, reflecting the design and fabrication of a non-standard, single-unit order rather than a batch
• Scaffold/access — for most single or small-run truss jobs, a birdcage or roof-edge scaffold section is needed rather than a full elevation scaffold; typically £600–£1,800 for a straightforward domestic access, following the same day-rate and erect/strike structure as scaffolding pricing guide
• Temporary propping and bracing — Acrow props, strongboys, and temporary binders to support adjacent trusses before the damaged one is removed; typically £150–£400 in hire cost plus 0.5–1 day of additional labour to install and later strike, following the general propping cost pattern in steel beam installation pricing guide
• Structural/truss engineer's fee — £350–£900 for a single truss survey and bespoke design; £600–£1,500 for a small-run (2–4 truss) intervention, more where the cause of failure needs investigating alongside the replacement design (see structural engineer)
• Roofer/carpenter day rate — £200–£280/day regional, £250–£380/day London and the South East, consistent with rates used across roofing and structural carpentry pricing in this wiki
• Building Control notification — Building Notice or Full Plans application; typically £200–£500 for straightforward domestic structural alteration work, varying by local authority or Registered Building Control Approver (RBCA)
• Restraint straps and fixings — modest material cost, typically £15–£40 per truss for wall-plate restraint straps at the specified centres
• Bracing reinstatement materials — timber battens/binders for longitudinal and diagonal bracing reinstatement, typically £60–£180 per truss depending on the bracing schedule
• Weatherproofing during the works — temporary tarpaulin/sheeting, typically £80–£200 per job, more for a longer exposure window on a larger intervention
• Roof covering reinstatement — underlay, battens, and matching tiles/slates over the affected area; typically £35–£70/m² depending on covering type, on top of the structural cost, and covered in more detail in roof repair pricing guide
• Lead time for the replacement truss — 1–3 weeks for like-for-like from an existing manufacturer's drawing; 2–5 weeks where a bespoke engineer's design is needed from scratch
• Investigating the underlying cause — where wet rot at bearing points is suspected (commonly linked to inadequate roof ventilation), factor in a small allowance (£100–£300) for probing and, if needed, a roof ventilation upgrade — replacing the truss without addressing the cause risks repeat failure
• VAT — standard rate 20% applies; no reduced-rate relief for structural roof repair work

Quick Reference Table

Detailed Guidance

Building the price bottom-up

Price these six components as separate line items, exactly as with any other structural roof intervention, then present the customer with a single fixed total:

1. Diagnosis and design — a survey to confirm the cause of failure (see roof truss replacement guide for the common causes: wet rot, storm damage, historic unauthorised alterations, fire, insect damage) and either a manufacturer's like-for-like drawing or a bespoke engineer's design.
2. Access — scaffold or tower scaffold sized to the actual extent of the work, not a generic "roof scaffold" assumption; a single truss near the ridge needs different access than one near the eaves.
3. Temporary works — propping and bracing the adjacent trusses, priced as its own line item given its safety-critical nature (see roof truss replacement guide for why this step cannot be skipped or improvised).
4. The replacement truss(es) — supplied to the confirmed design, plus restraint straps and bracing materials.
5. Installation labour — removal of the damaged truss(es), fitting the new truss, reinstating bracing exactly to the design/schedule, and reinstating the roof covering.
6. Building Control notification — Building Notice or Full Plans application and inspection fee, always required for this category of work.

Worked example 1 — single truss, like-for-like replacement, accessible roof

Scenario: A single Fink truss has failed at a bearing point due to wet rot, traced to a blocked eaves vent. Original manufacturer's drawings are available from the developer's Building Control file. The truss sits mid-roof on a straightforward 3-bed semi with good access; adjacent trusses are sound.

This sits toward the upper end of the single-truss range in the table above because it folds in the eaves vent repair and a full manufacturer drawing search — a job where drawings are already to hand and no ventilation remediation is needed would land closer to £2,000–£2,600 ex VAT.

Worked example 2 — small run of storm-damaged trusses, bespoke engineer design

Scenario: Storm damage has displaced bracing and cracked gang-nail plate connections across three adjacent trusses on a detached house. No original drawings are available (older property, pre-dates digital Building Control records), so a structural/truss engineer surveys the roof and designs bespoke replacements with a full bracing schedule.

This sits above the £4,000–£7,500 quick-reference band for a small run, reflecting the combination of a fully bespoke engineer's design (no like-for-like route available) and a larger 24m² area of roof covering reinstatement — a reminder that the quick reference table is a planning guide, not a substitute for pricing the actual scope confirmed on survey.

Why access so often dominates the bill

On a single-truss or small-run job, the truss timber itself is rarely more than 15-20% of the total cost — the scaffold or tower access needed to reach the affected area safely, and the temporary propping needed before any cutting starts, routinely cost more than the replacement structure. This mirrors the pattern seen across other access-driven roofing costs in this wiki (see scaffolding pricing guide and lead flashing replacement pricing guide, where access is explicitly called out as frequently exceeding the cost of the specialist work itself). Never quote truss replacement from the timber cost outward — build the price from the access and temporary works first, then add the truss and its installation.

Like-for-like vs bespoke design — the biggest single cost fork

Whether original manufacturer drawings exist changes both the cost and the programme materially. A like-for-like replacement, ordered against an existing design, needs no separate engineering fee beyond confirming the drawing matches the as-built roof, and lead times are typically shorter. A bespoke design — needed whenever drawings can't be traced, the roof is being modified, or the original design itself is suspect — adds a genuine structural/truss engineering fee (£350–£1,500 depending on scope) and typically 1–3 weeks to the lead time. Establish early in the survey whether drawings exist (check with the original developer, the local Building Control archive, or the truss manufacturer if known) before quoting, since guessing wrong on this single factor is the most common source of a badly under-priced truss job.

Attic trusses and larger structural interventions

Where a damaged conventional roof is being converted to attic trusses, or where the intervention extends to a full re-truss rather than a single/small-run replacement, this is a materially larger structural project — see roof truss replacement guide for why this should be treated as a loft-conversion-scale structural design from the outset rather than a "truss upgrade." Pricing for this scale of work follows the same components as this guide but at a materially larger multiple, and should be benchmarked against loft conversion pricing guide rather than the single/small-run figures in this article.

Common pricing mistakes

• Pricing the truss timber first and access as an afterthought — access and temporary works are usually the larger cost component, and treating them as a rounding error is the most common way this job gets underquoted
• Assuming like-for-like pricing before confirming original drawings exist — a bespoke engineer's design route costs materially more and takes longer; confirm which route applies before giving even a ballpark figure
• Skipping or under-pricing the underlying cause investigation — replacing a truss without addressing wet rot's ventilation cause, or without checking for historic unauthorised alterations to adjacent trusses, risks the same failure recurring and should be flagged (and priced) even if the customer wants to decline it
• Under-pricing bracing reinstatement — bracing that "looks similar" to what was there is not the same as bracing installed exactly to the design/schedule, and Building Control inspectors specifically check this; allow proper material and labour time for it, not a token allowance
• Treating Building Control notification as optional on a "small" job — any structural truss alteration is notifiable under Part A regardless of scale; there is no informal or unnotified route for this category of work

Frequently Asked Questions

Why is a single truss replacement so much more expensive than it sounds like it should be?

Because the truss timber itself is a small fraction of the job. Scaffold or tower access, temporary propping of the adjacent trusses (safety-critical and non-negotiable), the design/engineering route, Building Control notification, and roof covering reinstatement around the affected area all add up around what looks, from the ground, like "replacing one piece of timber." See roof truss replacement guide for why the structural reasoning behind this — trusses are engineered as a single interdependent unit — drives the process (and therefore the cost) this way.

Can I save money by skipping the structural engineer and matching the truss by eye?

No, and quoting this as a cost-saving option is a compliance and liability risk, not a genuine discount — see roof truss replacement guide for why a visual match isn't a substitute for a designed replacement. Building Control will not sign off a truss replacement without evidence of a designed intervention (either like-for-like manufacturer drawings or an engineer's design), and an unsigned-off structural alteration creates a title/insurance problem for the customer at resale.

Does scaffold cost less if it's only for a single truss rather than a full reroof?

Usually yes — a birdcage or partial roof-edge scaffold sized to the specific affected bay is cheaper than a full elevation scaffold, and this guide's figures assume that scaled-down access. However, where the affected truss sits at a difficult point on the roof (near a valley, hip, or where scaffold has to span an extension roof below), access costs can still be disproportionately high relative to the size of the structural work — always price access from an actual site survey, not a rule of thumb based on the number of trusses being replaced.

How much extra does addressing the underlying cause (e.g. a ventilation fault) add to the job?

Typically £100–£400 for straightforward remediation (clearing or adding eaves ventilation, resealing a failed underlay lap), but this can be significantly more if the ventilation fault is widespread across the roof rather than localised to the affected bay. Always flag this to the customer as a recommended (and separately priced) addition rather than bundling it silently into the truss replacement cost, since some customers will reasonably want to defer it — but the risk of repeat failure without it should be made explicit.

Regulations & Standards

• Building Regulations Approved Document A — structure; governs the notification and design standard for the truss replacement itself

• BS EN 14250 — timber structures — product requirements for prefabricated structural members assembled with punched metal plate fasteners (the manufacturing standard behind the replacement truss)

• BS EN 1995-1-1 (Eurocode 5) — structural design of timber structures, the design basis for the engineer's or manufacturer's replacement calculations

• BS 5975 — code of practice for temporary works procedures, relevant to pricing and planning the propping/bracing stage

• Building Safety Act 2022 and The Building (Registered Building Control Approvers etc.) (England) Regulations 2024 — governs which body (local authority or Registered Building Control Approver) issues the notification and fee

• Structural Timber Association (STA) — trussed rafter technical and commercial guidance

• GOV.UK — Approved Document A: Structure

• Institution of Structural Engineers — find a chartered engineer — typical engineer fee benchmarking for structural timber design

• LABC — Local Authority Building Control — Building Notice and Full Plans fee guidance by local authority

• roof truss replacement guide — the technique and structural reasoning this pricing guide is based on: truss types, diagnosis, temporary works sequence, Building Control process

• scaffolding pricing guide — access pricing that frequently dominates the cost of a single or small-run truss replacement

• structural engineer — when a structural or truss engineer is required, and typical fee bands for a bespoke design

• loft conversion pricing guide — benchmark pricing for larger structural interventions where truss replacement extends into a full re-truss or attic conversion

• roof repair pricing guide — general roof covering repair and access pricing relevant to the weatherproofing/reinstatement stage of a truss job