How Is Your Roofline?

Look up! How is your roofline fairing? Maintaining your property’s roofline is not something which ignites elation, yet, it is a very important aspect of preserving the integrity of your build.

Poorly maintained rooflines invite a whole host of problems for a home owner. Roof timbers can rot, guttering can leak onto brickwork and moisture can accumulate in the roof void. A tired roofline (the fascias and soffits) also has a drastic impact on the overall appearance of a residence. So if you are planning to invest in a new roofline then it is important to choose the right material for the job.

The choice is fundamentally between timber and PVC. Those who have already switched to PVC know that the installed costs of full replacement cellular PVC systems are now comparable to timber, and have major advantages in terms of maintenance costs and appearance.

The currently accepted life expectancy for PVC products within the construction industry is at least 35 years. It is unlikely that even the best external gloss paint currently available will last more than four years without requiring attention, and without this maintenance cycle a conventional timber roofline will soon fall into disrepair. When it does, ideally, the old timber boards should be completely removed and replaced with a new PVC fascia board. The board should be a minimum of 16mm thick in order for it to be capable of taking the weight of the lower row of tiles. Although capping boards are available and cost marginally less than a full replacement unit, they are only cosmetic and are not necessarily good value for money. There is always the risk that the original boards will carry on rotting beneath the capping board, a risk not worth taking.

Before beginning the refurbishment of your roofline it is imperative that you inspect the condition of the rafters and the roofing felt in particular. Roof tiles sit directly on top of the felt which, over time, can degrade and sever above the fascia. When this happens, the felt drops back and allows moisture into the roof structure causing unseen damage to occur in the form of rot.

In this case the degraded felt must be cut back and a damp proof material fitted under the exposed end of the felt. This should then properly dress down into the gutter to carry moisture away from under the tiles. Alternatively a rigid eaves protection system may be fitted. This sits on top of the fascia and supports the end of the old piece of roofing felt, completing the original function of the felt.


Damaged or rotten timber must be replaced and the rafter feet properly aligned ready for the installation of the new roofline system. This alignment is essential in order to produce a straight and flat surface to the boards. Hazardous materials like asbestos should be identified and professionally removed.

An essential element of a healthy roofline system is the ventilation it provides into the roof void. A poorly ventilated cold roof will increase the level of condensation and therefore encourage mould and rot. The Building Regulations set minimum levels of ventilation into the roof void, specifying that pitched roofs enclosing a standard cold roof void require a 10mm continuous air gap or equivalent at the eaves. Where a property has an attic and the ceiling follows the line of the roof a 25mm air gap must be provided. Things get slightly more complex with a mono-pitched roof where the requirements change and a 10mm gap must be provided at roofline and 5mm gap at the wall.

Ventilation can be provided in two ways. Air can be made to flow through the soffit board or over the top of the fascia board. The former can be achieved with slotted or vented soffit boards or trims. The over fascia method produces a “clean” soffit which overall has a better look to it. Over fascia ventilator units can be combined with an eaves protection flange which supports roofing felt behind the fascia to help eliminate the accumulation of water collection known as ‘ponding’.

PVC is a very practical material that comes in a range of ready-made sizes, various styles, some decorative, along with a choice of colours and wood grain effects to choose from. It has the added benefit of not requiring painting or other maintenance associated with timber boards.

There is no doubt that a PVC roofline says as much about a house as the choice of block-paved driveway. It is clean, practical and low maintenance which is so important is such an inaccessible location. So next time you step outside, look up, is your roofline letting you down?!