Roof Strengthening Installation and Photo Requirements for Re-Roofing Projects

When an older concrete, iron, or metal tile roof is replaced with longrun, the job is not just about the new roof sheets going on neatly. The structure beneath the roofing often needs strengthening at the same time, and the quality record needs to be strong enough to show that work was completed correctly.

That is especially important on large housing programmes and repeatable reroofing scopes, where multiple crews may be working across multiple properties to the same standard. In that environment, installation requirements and photo requirements need to be clear, practical, and easy to verify.

This is exactly why roof strengthening bulletins matter. They create consistency across the physical work and the documentation that sits behind it.

Why Roof Strengthening Matters During a Reroof

Replacing a heavier or different roof cladding with longrun often changes how loads and fixings are managed across the roof structure. That means the reroof scope may need more than just removal and replacement. It may also require targeted strengthening of key junctions so the roof framing, purlins, hips, valleys, and ridge areas are better secured.

In practical terms, that usually means the contractor needs to be clear on:

• which strengthening components are required
• where they are to be fitted
• what fixing pattern must be used
• what photographs are needed before the roof is closed back in

Without that clarity, two common problems appear quickly: inconsistent installation quality and weak QA evidence.

Top Plate Strengthening: CPC40 Fixings

For reroofing projects involving concrete, iron, or metal tile roofs being replaced with longrun, one of the most important requirements is top plate strengthening.

The requirement is typically to fix CPC40 brackets from the rafter to the top plate using Lumberlock Gold 35mm 14g screws. The fixing pattern depends on the spacing required by the project documentation:

• at 450mm centres, fix one CPC40 per rafter to the top plate
• at 900mm centres, fix two CPC40 brackets per rafter to the top plate where possible
• use four Gold Screws to fasten each CPC40

This is the kind of detail that has to be installed consistently. If one area is missed, or the fixing count is wrong, the completed work may look fine from above once the roof is on, but the strengthening standard underneath may not be what the project requires.

Hip and Valley Strengthening: MultiGrips

Hips and valleys are critical parts of the roof structure, so strengthening in these areas also needs to be handled consistently.

The standard approach is to install MultiGrips up both sides of hips and valleys to a maximum spacing of 1,800mm, using four Gold Screws per MultiGrip.

This is another good example of why photo records matter. Once the roofing is reinstated, the strengthening is hidden. If there is no visual record showing where the MultiGrips were fitted and how they were fixed off, there may be no easy way to verify the work later.

Ridge Strengthening: SBS4100 or FJS

Ridge strengthening requirements depend on how the top rafter meets the ridge board.

Where the top rafter is flush with the ridge board, SBS4100 brackets are used on each rafter. Where the top rafter sits below the ridge board, Floor Joist Stiffeners (FJS) are used on rafters at a maximum spacing of 1,800mm.

The fastening requirements are just as important as the product selection:

• SBS4100 brackets use six Gold Screws each
• FJS brackets use four Gold Screws each

Where suitable, SBS4100 brackets can be fitted over the ridge plate and under the top purlin, again at a maximum spacing of 1,800mm. FJS brackets can be fitted to the side face of the trusses where they join at the apex, also at a maximum spacing of 1,800mm.

If the structure does not allow SBS4100 or FJS brackets to be used, MultiGrips may be installed at each rafter and ridge board junction instead.

That last point matters because reroofing projects rarely encounter identical framing conditions at every property. The installation method has to reflect the actual structure on site, but the documentation still needs to clearly show why a particular strengthening solution was used.

Purlin Fastening: Existing vs New Purlins

Purlin fastening is another area where the difference between roof types matters.

When replacing an iron roof with longrun, the requirement for existing purlins is typically one Lumberlock 80mm 10g Blue Screw at every purlin-to-rafter junction.

When replacing a concrete tile or metal tile roof with longrun, or when replacing broken purlins with new ones, the requirement increases to two Blue Screws at every purlin-to-rafter junction.

That distinction is important. It is not enough to simply say that purlins were fixed. The QA record needs to show whether the purlins were existing or new, and whether the correct screw count was used for that condition.

Why Photo Requirements Are Just as Important as Installation Requirements

Roof strengthening work is usually concealed once the reroof is completed. That makes photo documentation a core part of quality assurance, not an afterthought.

Good photo records help confirm:

• the location where strengthening was required
• the bracket or fixing type that was installed
• the spacing and fastening pattern used
• the completed condition before the new roofing covers the work

For project managers, housing providers, and head contractors, these photos are often the only practical evidence that the hidden strengthening work was completed to standard.

What a Better Strengthening Photo Record Looks Like

For reroofing and housing programme work, a stronger photo record usually includes:

1. A location shot showing the relevant section of roof framing.
2. A closer photo showing the junction before strengthening is installed.
3. Progress photos showing the bracket or fastener being fitted.
4. A completed photo showing the final installed bracket and screw pattern.
5. Additional angle photos where needed to show ridge junctions, purlin connections, or otherwise hard-to-read details.

That sequence gives the client and QA team a much clearer record than a single after-photo taken at the end.

Why Consistency Matters on Kainga Ora and Multi-Property Programmes

On Kainga Ora reroofing programmes and similar large housing portfolios, consistency matters just as much as speed. Crews may be working across many properties, but the installation standard and documentation standard should stay the same from site to site.

That is why bulletins like this are valuable. They reduce guesswork. They help supervisors, installers, and QA teams work from the same expectations. They also make it easier to defend the completed work later if questions are raised about what sits beneath the roof cladding.

In short, good reroofing practice is not only about what gets installed. It is also about what can be proven.

A Small Hidden Detail That Deserves Serious Attention

Top plate brackets, MultiGrips, ridge strengthening components, and purlin screws may not be visible once the reroof is finished, but they are not minor details. These are the kinds of hidden construction elements that support the long-term integrity of the roof system.

That is why the strongest reroofing procedures always pair installation requirements with clear photo requirements. One without the other leaves gaps in the quality record.

Need Help With Complex Re-Roofing or QA-Sensitive Roofing Work?

Edwards & Hardy delivers reroofing projects where workmanship, consistency, and documentation all matter. If your project involves housing programmes, compliance-sensitive strengthening work, or large-scale reroofing scopes, contact our team to discuss the right approach.