Easy to use domestic roofing guide

INTRODUCTION:
This section of our site provides you with information on common faults with old roofs common in the London area. We also have details on repairing these faults and advise you on the options of repairing or re-roofing.
We hope you find this section both useful and informative. Please contact 1st Residential Roofing if you have any questions, in all cases we are happy to give free estimates across Central London and all other areas.

Common problems with old roofs
The life of a roof is finite; one should, therefore, acknowledge the fact that at some point in time it is liable to fail – and we are on hand to help.
The first signs of deterioration in the roof covering are usually indicated by the presence of broken and delaminated slates/ tiles or daylight showing through to the loft area. Cracks and eventual breakage are caused by the effects of weather and movement within the roof structure, which increase as the fixings decay.
Delamination occurs with slates and clay tiles, which are of a laminated structure. Water, which is absorbed into the slate or tile during the winter, can freeze and expand, causing the layers to separate and flake off.
A roof, which has an uneven surface, gives a reasonable indication that the roof timbers and battens are sagging. This may be due to decay in the timbers caused by water ingress or settlement within the building structure. The end result is a general disturbance of the roof covering, producing strain on the fixings and breaking of mortar joints.
Slates or tiles, which have slipped, indicate deterioration in the fixings, which may be nails or wooden pegs. If slipping has occurred in several places on the roof, it must be assumed that all the fixings are in an advanced stage of decay.
On closer examination, it may be found that the bedding mortar used at the ridges, verges and hips is cracked and decomposing allowing movement and water penetration to take place. Metal flashings and valleys may also require replacement as erosion and fatigue can produce hairline cracks allowing water to enter, which is mostly caused by incorrect installation.
Mortar fillet flashings are cheap and were common before the 1940’s, but they are generally less effective than metal due to their durability and inability to accommodate minor thermal and structural movement, which causes cracking. They are also susceptible to frost attack, which also results in the cracking of the mortar fillet.

Repair or re-roof
.Any faults already mentioned will leave a roof vulnerable to water penetration and further deterioration. It is necessary to inspect a roof thoroughly before any major refurbishment work in other areas is started and any faults rectified by taking one of the alternatives, which follow

Patching – A good option?
If the faults are confined to small areas and the remainder of the roof structure is sound, replacement of damaged slates or tiles may be the answer.
There could be a problem in obtaining slates or tiles of similar profile and colour due to tile or slate designs becoming obsolete; second-hand slates or tiles would have to be found.
However, it must be remembered that patching will not prevent deterioration in other parts of the roof and frequent inspections and repairs may be required. Patching is ugly, inconvenient and impractical and the cost of small repair work will rise annually.
This sort of treatment should be regarded as an uneconomic long-term solution.

Surface Coating
There are a number of surface treatments on the market designed to form a protective layer over slates or tiles. The coating compound is applied in a liquid state, which hardens off, sealing gaps and holding the slates or tiles in place.
This type of treatment does not remedy faults in tiling battens and rafters, which may continue to decay due to moist air becoming trapped in the roof space. Natural ventilation through the roof coverings is prevented and alternative methods would be required.
The life of the material is uncertain, and the British Standard B.S.5534 Slating & Tiling does not recommend the use of surface coatings either internally or externally.

Reroofing
Re-roofing offers many advantages over repairing. Upon the removal of the old coverings, the timber rafters can be closely examined, replacing and packing-up where necessary to bring the roof structure onto an even plane.
Roofing felt is installed providing a barrier against wind, driven snow, dirt from outside.
New battens, slates or tiles are laid, bringing the roof up to present-day standards and performance associated with newly constructed buildings.
Ventilation products are installed to provide adequate ventilation of the roof void in accordance with current Building Regulations.