The tell is usually repetition. A roof with one problem has a problem. A roof that has needed three repairs in three years is not a roof with three problems — it is a roof at the end of a service life.
When a Roof Needs Replacing, Not Repairing — practical guidance from the team running roof replacement on the Garden Route. Below are the five findings that mean replacement rather than repair, the one that catches most people out, and how to test the honesty of a contractor’s recommendation.
Repair is the right answer more often than you think
Start here, because the roofing industry has an incentive problem and it is worth naming.
A great many leaking roofs have a specific, localised, fixable cause: a cracked mortar fillet at a chimney, a blocked or undersized valley, a failed penetration detail, a batch of perished washers, a box gutter that needs re-laying. Those are repairs, they are not expensive, and the roof carries on for years afterwards.
A contractor who inspects a roof and recommends replacement without showing you a specific finding is selling, not diagnosing. Ask to be shown the thing that cannot be repaired, in a photograph, with its location. If it cannot be shown, treat it as unproven.
So the honest starting position is that repair is the default and replacement needs to be justified by a specific finding. The rest of this article is about what those findings are.
Availability quietly forces this decision more often than condition does. Discontinued tile profiles from the older Coverland, Marley and Monier ranges frequently cannot be matched, and an obsolete sheeting profile cannot always be rollformed to sit against what is there. Once a roof cannot be repaired with matching material, a patch repair becomes a visible patch and a future weak point, and the honest recommendation shifts to replacement even where the remaining sheets have life in them.
The five findings that mean replacement
1. A perished underlay. This is the big one, and it catches almost everyone. On a pitched tiled roof, the underlay is the actual waterproofing layer — the tiles shed the bulk of the water and the underlay catches what gets past. Bituminous felt underlays go brittle, tear at the fixings, sag into troughs and disintegrate. The tiles above can be perfectly sound. And because the underlay sits below the covering, it cannot be replaced from above. That means stripping and re-laying the covering — a re-roof, not a repair. It is usually possible to re-use sound tiles, so the cost is largely labour, battens and membrane, but it is still a re-roof and it should be described as one.
2. Repeat leaks in different places. Not the same leak returning — different leaks appearing in different areas over a short period. That pattern means the system is failing generally rather than at a point.
3. Widespread fixing or batten failure. Perished washers in one area are a repair. Corroded fixings across the whole roof, or battens that have rotted at the eaves and beyond, are a strip.
4. Perforated sheeting. Surface rust is treatable. Once the sheet has lost section and perforated, patching is a temporary measure rather than a repair.
5. Structural findings. Rotten rafter ends, cut truss members, missing bracing, corroded connections. These are not roofing repairs at all — they are structural work, and the covering usually has to come off to do them.
The underlay test you can do yourself
Because the underlay decides so much, it is worth knowing how to assess it without waiting for a contractor.
Take a torch into the roof space on a bright day and look up at the underside of the covering. You are looking for five things.
Daylight visible through the covering where there should be underlay.
Tears at the fixings, where battens are nailed through the membrane and it has split along the line.
Sagging into troughs between the rafters — a membrane that has stretched and now holds water rather than draining it to the eaves.
Brittleness. Touch it gently. Sound felt has some flex; perished felt crumbles.
Staining on the timbers or on the underside of the tiles, which tells you water has been getting past for a while.
Any two of those together and you are looking at a re-roof within a few years rather than a repair. It is worth knowing that before you spend money on the third patch.
What a re-roof actually involves
If replacement is the answer, it is worth knowing what you are buying so you can compare quotes properly.
Strip. Covering off, battens off, old underlay removed. This is the point at which whatever was hidden becomes visible, and a good quote identifies the likely findings rather than pretending a strip is a known quantity.
Structural check and repair. Rafter ends, battens, bracing, tie-downs, any cut members. Frequently there is something.
New underlay, lapped correctly and discharging into the gutter rather than behind it.
New battens at the correct centres, treated appropriately for the exposure.
Re-lay or re-cover. Sound tiles can usually be re-used; broken ones replaced. Or a new covering if you are changing type.
New flashings, valleys and ridge. These are the parts that were probably contributing to the problem, and re-using tired metal under a new roof is a false economy on the coast.
Rainwater goods while the access is there.
And it is the moment to fix the specification — better underlay, correct metal for the exposure, closer fixing at the edges, and any insulation or ventilation improvement. All of it is dramatically cheaper with the roof open.
Testing whether the recommendation is honest
Five questions that will tell you a great deal about whoever has just quoted you.
“Show me the finding.” A photograph, located. Anything that cannot be shown should be treated as unproven, particularly after a storm when door-to-door operators appear.
“Did you go into the roof space?” Half the diagnostic information is inside. An exterior-only survey that recommends a full replacement has not looked at the thing that decides it.
“What would a repair cost, and how long would you expect it to hold?” An honest contractor can answer both, including when the answer is “about two years, and then you will be doing this anyway”.
“Is everything on this list urgent?” A report where every item requires immediate action, from someone who can start on Monday, is a sales document. Real roofs have a mix of urgent, soon and monitor.
“Can I have the report and get a second price?” The answer to this one is the most informative of the five.
And pay for the inspection. A free inspection is paid for by the work that follows it, which puts the incentive in exactly the wrong place.
Frequently asked questions
How do I know if my roof needs replacing?
The strongest single indicator is the underlay, and you can check it yourself with a torch in the roof space — daylight through the covering, tears at the batten fixings, sagging between rafters, brittleness, or staining on the timbers. After that: leaks appearing in different places over a short period, widespread fixing or batten failure, perforated sheeting, and structural findings such as rotten rafter ends or cut truss members. Any of those points to replacement rather than repair.
Can a roof be repaired if the underlay has perished?
Not from above, and this is the point that catches most people. On a pitched roof the underlay is the layer that actually keeps water out once anything gets past the tiles, and it sits below the covering. Replacing it means stripping and re-laying — which is a re-roof. Sound tiles can usually be re-used, so the cost is mostly labour, battens and membrane rather than new tiles, but it should be described honestly as a re-roof rather than a repair.
Is it worth repairing an old roof?
Frequently, yes. Many leaks have a specific localised cause — a cracked mortar fillet, a blocked valley, a failed penetration detail, a batch of perished washers — and fixing those buys years at modest cost. The point at which it stops being worth it is repetition: a roof that has needed three repairs in three years is not a roof with three problems, and each further repair is money spent on a service life that is ending anyway.
How much of a roof can be re-used in a re-roof?
Usually more than people expect. Sound concrete or clay tiles can generally be lifted, stacked and re-laid, with only the broken ones replaced — so the cost of a tile re-roof is mostly labour, battens and new underlay rather than new tiles. What should not be re-used on the coast is the metalwork: flashings, valley linings and fixings that are already tired will fail long before the new work does, and replacing them with the roof open costs a fraction of doing it later.
Should I change from tile to metal when re-roofing?
It is worth considering, and it is the easier of the two conversions because it reduces the dead load on the trusses substantially. The trusses still need an engineer’s check since the load pattern changes, and the pitch has to suit the sheet profile. Going the other way — sheeting to tile — adds weight the structure was very likely never designed for and is a much more careful proposition.
How do I know a contractor is being honest about needing a new roof?
Ask to be shown the finding in a located photograph, ask whether they went into the roof space, ask what a repair would cost and how long it would hold, and ask whether every item on the list is genuinely urgent. Then ask whether you can take the report and get a second price. A contractor who is comfortable with all five is usually telling you the truth; one who resists the last one in particular is not.
Related reading
- Repair or replace a roof
- What a roof inspection should cover
- Common roof repairs on the Garden Route
- Roof replacement in George
- Roof repairs in George
Been told you need a new roof?
Get a second opinion before you commit. We will go into the roof space, photograph what we find, and tell you honestly whether it is a repair, a repair that buys two years, or a re-roof.
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