How To Repair Parapets & Lead Valleys

A “Stitch in Time” In Exeter

One of Rubba-Roof’s approved contractors has recently completed an interesting project involving the refurbishment and repair of parapets and lead valleys on a large Edwardian house in Exeter.

The owners had installed Photo Voltaic panels and an inspection of the parapets, gullies and leadworks indicated that refurbishment was a prudent course of action to avoid future leaks and the need for expensive emergency maintenance in the foreseeable future.

Rubba-Roof hopes that the following project notes may be of interest to anyone wishing to waterproof parapet masonry or seal old lead installations.

How To Repair Parapets With Rubba-Roof

The inside facings of parapets may be shaded for much of the year attracting damp and also wet materials such as leaf litter, mosses etc. that stay on the surface: the consequence is often an accelerated deterioration of the masonry or render facias.

Another common point of failure can be at the joint between the parapet wall and the valley gutter: water may lie here and these seams may also be subjected to expansion and contraction movements from within the building’s structure.

The photographs below show the parapet in this project.

parapet before treatment - Rubba-Roof

Here you see the condition of the parapet before refurbishment

parapet after treatment - Rubba-Roof

This shows the masonry after the application of a new render coat


The new render was given time to fully cure and primed with Rubba-Roof Primer to close any microporosity.

The picture also shows the parapet top fully coated with Rubba-Roof compound to ensure many more years of maintenance free weather resistance. The face of the parapet wall was then completed with a 1 mm thick application of Rubba-Roof compound.

Rubba-Roof’s exceptional adhesion, combined with its resistance to the establishment of lichens and mosses, make it the ideal choice for the waterproofing of vertical and horizontal masonry.

Useful Tips

Coat vertical surfaces with Rubba-Roof compound before stirring the contents of the tin; the slightly increased viscosity will minimise any curtaining or drips.

Pay particular attention to any seams between vertical and horizontal surfaces; the use of Rubba-Roof Reinforcing Fleece at these points will give enhanced strength to these vulnerable areas. More information about applying fleece >>

How To Repair Lead Valleys with Rubba-Roof

Lead has, until recently, been the automatic choice as a water and weather proofing membrane for valleys, gulleys and for flashings to brickwork and masonry. Lead’s ductility and robustness offer long lasting service but lead does have its drawbacks. It is very heavy and can impose significant loadings onto old substructures, such as underlying timbers and sheetings. Another point; lead requires specific skills for correct installation and, once installed on a building, lead is often the target for metal thieves who do great damage when ripping it off. Finally, lead itself and the the plumbing skills needed for its effective installation, can prove to be expensive.

Rubba-Roof is an economical and attractive alternative to lead for waterproofing roofs, masonry and brickwork.

This shows the stepped lead work before remediation

This shows the stepped lead work before remediation


As can be seen from the photographs, this stepped lead catchment gulley was showing signs of age and some distress at the joints. Rubba-Roof was the ideal choice for an overlay membrane: being a cold applied, liquid polyurethane. The contractor was able to easily and accurately follow the existing profiles, even over the wood-roll centre seam. The work was completed in a few hours and the lead is now protected with Rubba-Roof’s guaranteed elastomeric compound.

This shows the finished job. All the detailing is neatly covered and there was no need for expensive materials or the use of torch flame on the roof

This shows the finished job. All the detailing is neatly covered and there was no need for expensive materials or the use of torch flame on the roof


So, peace of mind for the owner and no opportunity for the light fingered!

Useful Tips

Always rub down metal substrates remove any oxidisation latence and loose surface particles before applying Rubba-Roof compound. On copper it is best to passivate the surface with an acid wash before applying Rubba-Roof.

ALWAYS wear a mask and protective clothing. Only apply Rubba-Roof to a DRY surface.
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