What roof spread actually means
The first thing to establish with roof spread is the pattern. This guide is specifically about outward movement at the feet of rafters pushing on the tops of walls. For roof spread, details such as timing, location and recent changes often narrow the possibilities before any roof covering is lifted.
The most helpful observations are external walls bulging or leaning near eaves level, horizontal cracking high on masonry, and rafters or ceiling ties that have been cut, removed or altered. If you can describe those clearly, an inspection for roof spread is more likely to concentrate on the right part of the roof.
Why rafters can push walls outwards
The main possibilities are inadequate restraint between opposite rafters, removed ceiling ties during loft alterations, and failed or poorly connected structural members.
Other causes worth considering are long-term roof loading on an unsuitable arrangement. With roof spread, the important thing is to match the cause to outward movement at the feet of rafters pushing on the tops of walls, rather than treating it as a general roofing fault. For roof spread, that distinction can prevent work being carried out on a nearby detail that happens to look worn but is not responsible for what you are seeing.
Clues at eaves level are especially important
From a safe position, you can look along the outside wall line for outward bowing near the eaves. You can also inspect accessible loft ties and connections without disturbing the structure.
It is also useful to review whether walls or roof spaces have been altered. For roof spread, write down what you can see and, where relevant, what the weather was doing at the time. A short sequence of photographs of roof spread from the same safe viewpoint can show whether the condition is changing. When checking roof spread, avoid walking on the roof or leaning out of windows; the aim is to collect useful information without creating another problem.
New movement needs proper assessment
This becomes more urgent if the wall is visibly moving outward, new cracking is appearing high on the wall, and ties or key supports have clearly failed. With roof spread, those signs suggest that waiting for a convenient time could allow more water entry, falling material or further damage.
If those warning signs are absent, roof spread may not need an emergency call-out, but it is still worth arranging a proper look before the condition gets worse. In this case, change over time matters: outward movement at the feet of rafters pushing on the tops of walls that has been stable for a long period is a different situation from something that has appeared recently or is becoming more obvious after each spell of bad weather.
This is a structural question, not just a tile problem
A roofer looking at roof spread should inspect the roof structure rather than just the covering, then identify how horizontal forces are being restrained.
They may also need to work with a structural engineer where strengthening or wall restraint is required. Because this page is about roof spread, the inspection should stay focused on that problem and the nearby details that could realistically produce it. For roof spread, ask what they think has failed, what evidence supports that view, and whether the proposed work is local or part of a wider defect. A clear explanation of roof spread is more useful than a quotation that simply lists materials.
Restraint must be restored, not disguised
Depending on what is found, a suitable repair might restore effective ties or structural restraint, repair damaged roof members, or stabilise affected masonry where necessary rather than simply repointing cracks.
For roof spread, the best option is the one that deals with outward movement at the feet of rafters pushing on the tops of walls and leaves the surrounding roof working as it should. If wider work is proposed for roof spread, ask why a local repair would not be reliable, what condition the adjoining materials are in, and whether access costs make it sensible to combine closely related repairs. The answer should make sense for roof spread, not read like a standard reroofing recommendation.
This guide is general information about roof spread. The cause of roof spread at an individual property can only be confirmed by inspecting the relevant roof area.