How to Repair a Roof with Total Roofing Solutions

Total Roofing Solutions are roofers in Preston. Here they advise on smaller repairs that you may feel able to take on yourself. If you do not feel confident doing any work at heights or are simply too busy, Total Roofing Solutions will be happy to take on the task!

Roofs needing repair don’t have to be a death knell for a renovation project. From fallen slates to sagging roof slopes, we explain what you need to look out for and what’s involved in fixing common roofing problems

When buying a property, it’s common to find roof defects flagged up in surveys and valuations. Even straightforward repairs can be worrying in terms of cost and inconvenience.

Fortunately, needing to completely re-roof your property is usually unnecessary and as long as the roof is well maintained, can be avoided. There can be potentially serious issues that require urgent attention to prevent leaks.

Here, we explain what to look out for, the repairs required, and the potential costs involved.

All figures provided by Total Roofing solutions depend on condition, property type and size, and location.

Defective Pointing

Identification

Defective pointing can be identified by:

  • gaps and loose mortar at the joints between ridge tiles (which run along the top of the roof), hip tiles that cap the ‘corners’ on hipped roofs, or to verges of gables or lean-to roof slopes
  • slipped ridge and/or hip tiles
  • missing hip irons (used to secure the tile at the bottom of the hip)
  • leaks and damp within the loft and to the upper roof timbers

Implications

While relatively minor defects, they’re fairly common. If left unchecked, the ingress of damp could decay roof timbers. Storms, such as our recent spell of hurricanes, can dislodge loose ridge tiles.

Remedial Work and Costs

Repair is a fairly straightforward task:

  • Eroded mortar joints need repointing = £28 for one tile, plus £10 per additional tile (add £10 if a new hip iron is needed).
  • Ridge/hip tiles which have come loose = £36 per tile, plus £19 for each additional tile.
  • Verges requiring pointing up with mortar = £32 per tile and £13 thereafter.

Missing Slates and Tiles

Identification

It’s not unusual to spot small gaps where one or two tiles or slates have slipped or cracked. In most cases, don’t worry if it is just a couple of slates that are missing – the way slates are laid means they are layered so there is still protection from the elements should one slip.

Most roofs built at the Fifties also have a layer of underlay providing a secondary defence. Any wind-blown rain that penetrates under the tiles should be safely channelled away down to the gutters.

Older roofs were built without any underlay, and instead relied on a good flow of air ventilating the loft to waft away any resulting damp. Due to cavity wall insulation, double glazing and other protective elements, air flow is at a minimum and so damp can be left to fester.

Implications

The odd dislodged or missing tile, is often caused by storm damage, or people walking on the roof for TV aerial/satellite dish installation. A missing tile/slate is not usually a critical defect, but repair shouldn’t be left for too long, especially on roofs clad with larger interlocking tiles (with less overlap), and on older roofs with torn, sagging or non-existent underlay.

Gaps between adjacent tiles/slates near gable ends or party walls can also develop where the roof slopes have settled more than the walls. Spaces of up to 10mm either side of each tile are not normally significant, as the lapped tiles underneath cover the gap.

Remedial Work

If there are only a few slipped or missing tiles or slates, they can usually be replaced fairly easily. On shallow pitched roofs the underfelt can sag, diverting rainwater down wall cavities. This may mean the lower layers of underfelt need to be replaced.

Tiles can be prone to localised defects such as broken nibs. Even long-lasting plain clay tiles can eventually start to erode and crack across the middle or ‘spall’ in layers. It’s relatively easy to replace tiles because, unlike slates, they’re typically only nailed every fourth or fifth course.

To remove a broken tile:

  1. Lift the two tiles above it with wooden wedges.
  2. Use a bricklayer’s trowel to raise the damaged tile off the batten.
  3. Carefully slide it out.
  4. Ease a replacement tile into its place.
  5. Hook the nib over the batten.

Slate is a very durable natural material, but old fixing nails are prone to corrosion. Old slates can crack across their width and middle, or even start to delaminate (flake) in layers, too.

However, because each slate is nailed to a batten, and slate sizes vary, they are more difficult to lift out and replace. Slipped slates can be refixed using copper or aluminium alloy nails. Or, if just one or two are loose, then they can be secured using small folded metal clips known as ‘tingles’.

Potential Costs

  • Replacing a broken tile/slate = about £26 with £9 for each additional tile/slate.
  • Refixing an existing tile/slate = around £60 for one to five tiles next to one another, plus hire of access equipment.

Note that small jobs like this are likely to attract an additional ‘hassle-factor’ price premium.

Sagging Roof Slopes

Implications

Slight settlement is not usually a problem; it’s fairly common next to gable ends and party walls where the rafters have settled more than adjoining masonry. If the structure is satisfactory and there’s no leakage, a fair amount of historic settlement can be acceptable.

On the other hand, in more severe cases a structural engineer may need to be consulted and remedial structural work undertaken. These causes include:

  • Overloading — this can happen when the roof is slated or tiled with heavier materials than the roof can bear without strengthening the roof timbers.
  • Weak roof timbers — rafters may have been undersized or spaced too far apart when the house was originally built. Or, they may have been cut without the rafters being strengthened.
  • Roof spread — the rafters have pushed outwards causing the top of the wall to bulge, which means that the rafters may sink and cause the roof to dip in the middle.
  • Rotten or infested timbers — this is usually due to long-term leakage and poor ventilation.

Remedial Work

Overloaded or weakened roofs can be repaired by installing additional purlins and struts to improve support. This is fairly simple carpentry and shouldn’t be too expensive, providing that access is reasonable.

If sagging is due to settlement to supporting internal walls below, then the walls must be stabilised.

With roof spread, the ceiling joists normally act as collars restraining the rafters from pushing the walls outwards, so new collars may need to be installed or tie rods inserted through the upper walls.

Rotten timbers can be cut out and new timbers spliced alongside (or bolted with metal plates). The source of leakage must be fixed and ventilation improved to disperse moisture.

Slates or Tiles Nearing the End of Their Life

Identification

If 10 or more tiles per slope are damaged or missing, the roof is likely to be nearing the end of its useful life and will need stripping and re-covering. With slate roofs, look for similar numbers of loose slates that have been refixed with small metal ‘tingles’. In the loft, there may be damp smells and localised staining from water ingress.

The longevity of a roof covering depends on the quality and age of the material, and the degree of exposure. The lifespan of traditional roof coverings is generally superior to later manufactured materials.

  • Handmade clay tiles or stone slates can last 250 years or more compared to around 70 or less for some types of concrete tile.

Old tiles and slates can absorb water which then freezes and expands. White powdery salts under the tiles can indicate erosion and the projecting nibs at the top of each tile can break. In older slate roofs, the undersides of slates can be checked for signs of softening and flaking.

Implications

The need for complete re-covering is rare, but is a major undertaking. Surveyors can sometimes be guilty of erring on the side of caution, so get a second opinion before major works. The urgency of this task will also depend on the extent of the deterioration.

It’s worth noting that some roofers may be tempted to utilise inferior, cheaper materials when recladding older roofs. Like-for-like repairs are preferable on natural clay and slate roofs.

On 20th-century homes, asbestos-fibre artificial slates and tiles are fairly rare, but likely to incur additional costs for stripping and disposal.

Remedial Work

The roof should be stripped down to the rafters, new breathable underlay installed, rebattened and finally re-covered. With natural slate or clay tiles, it is often possible to salvage and reuse at least 50 per cent of the originals (reducing the cost of repair).

Costs of Complete Roof Re-covering

Remedial Work Required Labour and Materials**
Strip roof of tiles/slates, battens and felt £18/m²
Refelt, batten and re-tile/slate stripped roof using new tiles/slates:

Plain clay tiles

Natural slate

Interlocking concrete tiles

Artificial slate

105/m²

£151/m²

£44/m²

£106/m²

New ridge/hip tiles From £70/m²
Verges/undercloak pointed From £10/m²
Double eaves courses pointed From £14/m²

**Approximate cost including VAT.

 

Defective Flashing

Identification

Cracking can develop where roof slopes abut dormers, parapet walls and subsidiary roofs, or around objects such as chimney stacks and internal soil pipes that are projecting through the roof. The resulting leaks and damp patches can be seen in lofts, ceilings, walls and chimney stacks.

Lead flashings are very durable but can sometimes come loose. More rarely, old lead or zinc flashings may have split or corroded. Mortar fillets are a cheap alternative to lead and are particularly prone to cracking. Short-life tape repairs may even have been applied, or flashings painted to temporarily seal leaks.

Implications

These sorts of defects are a common cause of leaks in older properties or extensions of poor-quality construction. Over time, ingress of damp may have caused adjoining timbers to rot, and urgent repair is normally required to prevent deterioration.

Remedial Work

Such issues are not too difficult to fix, although replacing any decayed timbers will add to the complexity and cost.

Defective flashings should be replaced with new leadwork. Lead is the best material to use. Although relatively expensive, the cost can be mitigated by recycling the valuable old lead. Where a flashing has simply come loose, it may only need localised refixing.

Roofs on terraced houses can also suffer leaks where they meet at party walls. This tends to be worse where each house has a different type of roof covering. In this case, localised stripping will be required with the provision of sheets of lead (soakers) under the joints, or new flashings at parapets.

Replacing Valleys

Valleys are the junctions between two adjoining roof slopes which allow rainwater to run to the guttering. Valleys made with preformed tiles are relatively robust and any defective tiles can be replaced. Traditional open valleys have exposed linings which can deteriorate over time. Furthermore, on roofs clad with large interlocking tiles, it’s also common for the mortar upstands either side to crack and come loose. They may simply need pointing up. Alternatively, valleys can be relined using preformed valley trays of glass-reinforced polyester.

With older roofs, replacing traditional leadwork with matching new materials is advisable. Although lead is a more expensive material, it’s worth noting that labour and access account for the majority of the job cost. To replace a defective lead or zinc valley on a typical Victorian slate or tiled roof:

  1. The old lining is stripped back.
  2. The timber base is checked to see if it’s in sound condition.
  3. The old lining can then be replaced with new strips of code 4-thickness lead turned back and raised up at the edges (maybe laid in several lengths overlapped by a minimum 150mm).
  4. A thin layer of fibrous material is inserted between the lead and the valley board (such as breathable membrane roofing felt — but not mineral felt).
  5. The lead is finally fixed in place with copper nails hidden under the overlaps.

Typical labour costs will be about £250, with materials (lead sheet and a few tiles/slates) costing around £200 — plus the hire of the access/scaffold tower.

Scaffold Hire and Costs

The cost of scaffolding and access equipment hire needs to be added to the approximate prices for any of the jobs outlined in this piece.

Total Roofing Solutions offer Scaffold Hire for FREE so it’s all part of the service.

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