How Do You Know If Your Roof Has Storm Damage in Aberdare?

Find Your Position in the Row Before You Look at the Roof

A terrace is an accidental piece of wind engineering. The houses in the middle shelter each other: their roof slopes form one continuous plane and moving air has nothing to catch. The ends are another matter entirely, because at the end of a row the wind meets an edge, and edges are where roofs fail.

So the first question is not what your roof looks like. It is which of these you are.

• End of terrace. Check the verge — the sloping edge running up the gable — along its whole length, and the gable end itself.
• Top house of a row that steps up the valley side. Check the ridge and the upper courses; you stand above your neighbour's shelter.
• Mid-terrace. Check the ridge line, because it is the one part of your roof with no neighbour to protect it.
• Beside a gap, a lane or an entry. Treat the elevation facing the gap as an end-of-terrace edge, because that is what it is.
• Next to a higher extension or roof. Check the junction and the flashing where the step occurs.

What to Look For on a Slate Roof, Specifically

Most of the older housing here is Welsh slate, and slate fails in a way that gives a distinctive signature. A slate is held by two nails near its head, and it is the nails that age rather than the slate. Welsh slate routinely outlasts its fixings.

So on a slate roof you are not usually looking for breakage. You are looking for movement.

• A dark rectangle in the slope — a missing slate showing the felt or the batten beneath
• A slate that has slid downwards and now sits lower than the course it belongs to
• A slate lifted at its tail so it sits at a different angle from its neighbours
• Whole slates, unbroken, on the ground or in a lower gutter
• A slate wedged in a valley gutter, which is a blockage as well as a gap

That fourth one is the important signal. Unbroken slate on the ground with clean nail holes means the fixings let go, and failing fixings are a condition of the whole slope rather than of one spot. Keep whatever you find; do not put it in the bin.

The Ridge Line, and Why It Is Worth Twenty Seconds

Stand back far enough to see the whole length of the ridge and look along it as you would sight along a plank. It should be straight and evenly spaced.

Ridge tiles here are traditionally bedded on mortar, and mortar is rigid while the roof beneath it moves with temperature. Over decades the bond cracks, so a ridge tile ends up sitting in place rather than fixed in place, and the wind that finally dislodges it does not have to be exceptional.

A ridge tile out of line matters twice over. It opens the highest point of the roof to driven rain, and on a terrace stepping up a valley side it has a long way to fall and can reach a neighbour's property.

The Back of the House Is Where the Leaks Are

Almost every terrace here has gained something at the back over the years — a kitchen extension, a bathroom, an outhouse. Where that lower roof meets the main roof there is a valley or a flashed junction, and those handle a great deal of water through a very small space.

A blocked valley is one of the most common causes of a storm leak with nothing whatever visible from the street. Water backs up above the level of the slate either side and runs underneath it. Storms supply the blockage and the water in the same night.

If you can see the rear roof from an upstairs window at the back, that is the view worth taking. Look for debris sitting in the valley, and for water running where it should not during the next spell of rain.

From the Loft

Go up in daylight, take a torch anyway, stay on the joists, and do not go at all if the ceiling below is bulging or dripping.

• Daylight through the roof where there should be none
• Wet or darkened rafters, or water running down one
• Damp or flattened insulation, particularly near the eaves
• Staining on the underside of the felt, and any tear in it
• Daylight or damp around the chimney where it passes through

On an older terrace there may be no underlay at all beneath the slate — many were built without it. If that is your roof, a single displaced slate puts water straight onto the timbers, and the loft is where you will see it first.

The Chimney, and the One Shared With Next Door

Terraces here carry a great many stacks, a large share of them sitting on the party line between two properties and most of them no longer in use. That combination is worth a specific look after bad weather.

A stack without a working flue has nothing drying it from the inside, so it stays damp, and damp masonry weathers faster than dry masonry. A chimney unused since central heating arrived can be in considerably worse condition than it looks from the pavement. From the ground, check that the pots are upright, that the mortar cap at the top has not cracked away, and that the lead flashing where the stack passes through the roof sits flat against the brickwork rather than standing away from it.

Where a stack straddles the party line, the useful sequence is to establish what actually needs doing before anybody starts discussing who pays for it. We can assess the stack and the roof around it and set that out in writing, which is usually the information both households need in order to get anywhere.

What None of This Will Find

Storms loosen material without removing it, and fatigue fixings that fail weeks later in a much smaller wind. That is why a roof can come through a named storm apparently intact and then lose slates in an ordinary February gale.

If your property came through something severe, an assessment is worth having even when nothing looks wrong. T & T Roofing South Wales assesses storm damage across Aberdare and the Cynon Valley free and without obligation, and if we find nothing we will say so.