Installing Membrane and Battens on a New Roof in Redcliffe

With the timber structure checked and confirmed sound, attention turns to the layers that sit between the rafters and the visible tiles or slates on a Redcliffe roof. A breathable roofing membrane is fitted first, running horizontally across the rafters from eaves to ridge with generous overlaps at each join. This membrane acts as the roof's secondary line of defence, catching any wind-driven rain or snow that might get past the outer covering while also allowing moisture from inside the roof space to escape.

Choosing the right membrane matters more than many homeowners realise, particularly on a site close to the Floating Harbour where the roof can be exposed to driving rain off the water. A higher specification, vapour-permeable membrane is often the sensible choice here, since it copes well with sustained wet weather while still letting the roof space breathe correctly. On converted buildings in Redcliffe with less conventional roof shapes, extra care is also taken around abutments and junctions where the membrane needs to be dressed carefully rather than simply run straight across.

Once the membrane is secure, battens are fixed horizontally across it at a spacing calculated for the specific tile or slate being used. This spacing, known as the gauge, has to be worked out precisely for each roof rather than assumed from a standard chart, since roof pitch, tile size and any interruptions such as dormers or rooflights all affect the calculation. Getting the gauge wrong even slightly can mean tiles that do not sit correctly or a finished roof that looks uneven.

Batten quality is just as important as positioning. Treated timber suitable for the expected exposure is used, and fixings are chosen to hold firm in a location where wind loading off the harbour and surrounding open ground needs to be taken seriously.

Each batten is checked for straightness before fixing, since a warped or bowed length can throw off an otherwise carefully calculated gauge and cause tiles further along the course to sit unevenly. Battens are also fixed into sound timber rather than simply nailed through the membrane into whatever lies beneath, which means the earlier structural inspection directly informs how secure this stage can be. On roofs with valleys, hips or dormers, battens have to be cut and returned neatly around these features so the fixing pattern remains consistent right up to each junction, rather than stopping short and leaving tiles under-supported.

Counter-battens are sometimes introduced as well, particularly where a ventilated gap is wanted above the membrane, creating a clear airflow path that helps manage moisture before it can reach the timber below.

These layers are never seen once the roof is finished, but they do more than almost anything else to determine how well it performs over the coming decades. Brunel Roofing Bristol takes as much care over membrane and battens as over the visible tiles, and we are happy to explain our approach if you are planning a re-roof in Redcliffe.

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