Other roof issues

Parapet leaks

Parapets are late 1600s style and a common 1700s addition. The cloaking of timber frames with brick facades causes some difficult detailing at window reveals and roof junctions. As many rural buildings were still built essentially using vernacular techniques, some of these details require frequent attention. The most troublesome detail of the classical style is the parapet, which may or may not include a gutter.

Problems include:

• Leaks caused by lead poorly formed into outlet, or insufficiently large laps on lead. Check all laps and clips, and check for any slight cracks to corners, if the lead looks as though it has been reused.
• Copings not sealed, or cracked.
• The main body of the parapet is not separated by a damp-proof course, allowing water to track down into internal walls.
• Over-application of temporary liquid sealants, bitumen or felts. These often fail in the same place repeatedly, with little effect gained from re-patching.
• Blocked outlet or hopper. Often difficult to reach. The use of wire mesh or nylon netting can help reduce the number of times the hopper has to be attended to.

Leaks of complex rooflines

Complex rooflines are mainly found on altered vernacular houses and late 1600s designed houses.

The increase in the size of the footprint of houses made the spanning of walls more complex. In the later 1600s the introduction of internal staircases also added complicated details such as skylights. Often these roofs have hidden valleys and ridges. Any roof with numerous slopes and hips is likely to be more prone to leaks.

Often the main problem is not identifying where the problem is, but getting to it. Care needs to be taken that inspections and work on the roof do not dislodge or break other tiles.

Emergency repairs that were intended to be short-term are often left unattended once the emergency has passed. Because these defects are in areas that are invisible from the ground, they often go undetected until they fail completely.

The introduction of rolled sheet lead resulted in marked improvements to these types of roofs.

There is a great temptation to work from hydraulic access platforms to undertake this type of work, but it is dangerous to handle heavy materials such as lead at heights from small platforms.

Gutters decanting water into timber frames and earth walls

Gutters added in later periods can be poorly considered. Cracks in cast iron gutters and flush eaves can easily decant water into the heads of walls. These defects tend to manifest themselves quickly and the remedy is usually easily identifiable. In respect to cracked gutters and bad joints, it may not be worth trying to preserve the original guttering in inaccessible places, as very few repair systems cope with complex expansion patterns and the defect can quickly return.

Non-existent or ineffective underground drainage

Downpipes are often assumed to decant into functioning drain runs. However, even if a pipe is found to be clear, it is worth checking the run of the pipe. Soakaways can silt up or become ineffective in heavy rainfall, and can be the cause of intermittent high water tables close to walls that have no damp-proof courses.