How Are Damaged Roof Ridges Repaired?

Three Things People Mean

The ridge tiles. The capping along the apex. Loose, cracked or missing, usually because mortar bedding has failed. This is the common one.

The hips. The external angles running down from the ridge to the corners on a hipped roof. Same materials, same failure, plus one extra problem covered below.

The ridge board or the structure. The timber the rafters meet at the apex, and the rafters themselves. If the line of the ridge has sagged rather than individual tiles having moved, this is what is being talked about, and it is not a tiling job.

Establishing which one you have is the first thing worth doing, because they have very little to do with each other.

A Sagging Ridge Line

Look along the ridge from a distance. Individual tiles out of place produce a stepped or gappy line. A smooth curve dipping in the middle is different - that is the structure below.

It can be historic and stable. A great many old roofs have a gentle sag that settled a century ago and has not moved since, and it is part of the character rather than a fault.

It can also be progressive, and the usual causes are a rafter or purlin that has lost support, spreading at the feet where the rafters push the walls outward, or timber that has decayed - often at the eaves, where wet gets in and ventilation is worst.

The honest position here is that we are roofers. We can tell you what we find and we can renew decayed timber where it is a defined repair, but a ridge line that is actively moving wants a structural engineer or a surveyor looking at it. Recovering the tiles over a structure that is still deflecting treats the symptom.

Hips, and the Thing at the Bottom of Them

Hips are repaired the same way as ridges - rebedded, or converted to a dry hip system - with one addition that matters.

A hip runs downhill to a corner, so gravity is trying to slide the hip tiles off the end of it. There should be a hip iron at the foot: a small metal bracket screwed to the hip rafter that physically stops the bottom tile going anywhere.

On older roofs it has frequently rusted away, and nobody has looked. And the bottom of a hip is nearly always directly above a door, a drive or a path - so it is both the tile most likely to move and the one in the worst place to do it.

Any hip repair should include checking or renewing the hip iron. If somebody has rebedded a hip and left a corroded stub of iron at the bottom of it, the job is not finished.

Long Runs and Larger Buildings

Deeside has a lot of building that is not a semi, and ridge work scales awkwardly.

On a long terrace, a school, a unit or a warehouse the ridge run can be tens of metres. The access to reach it is a substantial part of the cost and it does not reduce much whether you are doing five metres or fifty - so doing a failing ridge in short sections over several years is one of the more expensive ways to spend money on a roof.

The sensible approach on a long run is to survey the whole line, do the sections that have actually failed plus anything obviously about to, and get a view on the rest so it can be budgeted rather than reacted to. Where a run is genuinely all the same age and condition, doing it in one go under one access arrangement is usually the cheapest total.

On profiled sheet industrial roofs the equivalent detail is the ridge capping and its fixings and seals, which fail by corrosion and by working loose rather than by mortar cracking - but the access arithmetic is exactly the same.

What Should Be in the Quotation

Which of the three things is being repaired. Whether the whole run or a section. Whether it is being rebedded or dry-fixed. Whether hip irons are being checked. And what happens if timber underneath turns out to be decayed once the tiles are off, because that is the finding that changes the job.

On a commercial building, add the access arrangement and whether work can happen during trading hours. Those two shape the price more than the roofing does.