The short answer
Yes, trees close to a roof can cause damage, though mostly in slow ways: leaves block gutters and valleys, shade keeps the roof damp so moss thrives, and branches rub or fall in strong wind. Trimming back branches and clearing debris regularly keeps most problems small. Larger or protected trees need professional advice and sometimes permission.
Leaves, needles and blocked channels
The most common problem is also the least dramatic. Leaves, seeds, twigs and needles drop onto the roof and wash into the lowest places: gutters, valleys, the junction behind a chimney and the corner where an extension meets the main house. When those channels clog, water has nowhere to go. It backs up, runs past the edge of the channel or sits against the wall, and that is how a damp patch appears on a ceiling that has no obvious hole above it.
A valley is a particular weak spot, since it carries water from two slopes. A clogged valley can overflow beneath the covering at its edges. Our page on moss blocking gutters covers the clearing side of this in more detail. Houses with a big tree close by may need gutters and valleys cleared more often than houses without, particularly after leaf fall in autumn.
Shade, damp and moss
A tree that shades a slope keeps it cooler and slower to dry. Moss and algae need damp, and a roof that stays damp grows them quickly. The effect is most obvious on the side closest to the canopy, and it is a large part of why one slope of a roof can look green while the other looks clear. For the wider picture of how shade and texture combine, read why moss grows on roofs.
Moss in itself is not always a disaster, yet a deep cushion of it keeps water pressed on the covering, can lift the edge of tiles and feeds more debris into the gutters. Frost then works on the saturated surface and can break up older, softer tiles and slate. If the shade comes from one tree that could be cut back sensibly, the benefit is lasting, because the roof dries out better and cleaning is needed less often.
Branches that rub, snap or fall
Branches that touch the roof move with the wind. Over a season or two, that movement can scuff the surface of a tile, wear the glaze on a clay one, and knock the edge of a slate. A branch that overhangs the ridge or a chimney stack can pull at flashings and pointing.
In strong wind, small branches can break away and land on the roof. The risk is mostly to tiles and slates that are already slipped or weak, since a healthy covering takes a light knock well. A large limb is a different matter and can damage rafters or break through a flat roof deck. If you see a dead or split branch above the house, do not wait for the next storm. A tree surgeon can assess it, and a roofer can then check and make safe whatever has been hit. Trees close to a flat roof deserve extra attention, since the covering can be punctured by a falling twig.
Sap, droppings and stains
Some trees drop sticky sap or honeydew onto whatever is below. On a roof it traps dust, feeds algae and leaves dark patches that do not rinse away easily. Birds roosting in branches add droppings in the same place. Rotting leaves also stain, and tannin from some of them marks pale surfaces.
Stains are mostly cosmetic, but a coating of sticky residue gives moss a better start and can clog a rooflight or the glass of a conservatory roof. If the roof has solar panels, branches overhead can cast shade across them and reduce what they produce, and the gap beneath is attractive to birds. Our answer on solar panel bird proofing explains how the gap is closed up. A roof that is cleaned and looked over at the same visit gives you the full picture of what the tree is doing.
Roots, neighbours and permission to cut
Roots do not hurt the roof itself, but they can affect walls and foundations, and any movement in a wall shows up in the roof as cracked pointing, slipped tiles and gaps around chimneys. If you see cracks, ask for a building surveyor's view, not just a roofer's.
On cutting back, check first who owns the tree. Branches overhanging your boundary can generally be trimmed, but only up to the boundary line; going further can lead to a court claim, and a tree may be protected by a preservation order or stand within a conservation area. Check with Swindon Borough Council's planning team, or the council that covers your town, before you do anything to a large or notable tree. Wildlife matters too: nesting birds and bats are protected, so timing the work outside the nesting season is sensible. Tree work at height is a job for a qualified tree surgeon.
Looking after a roof under trees
A small routine does most of the work. Clear gutters and valleys after leaf fall and again in spring. Trim branches back so that none touch the roof, and keep clear of the chimney. Check from the garden for slipped tiles and moss building at the shaded side. Do not climb up yourself, since wet leaves on a roof are slippery.
When you are ready, we will inspect the roof, take photographs and send a written quote covering only the cleaning or repairs the roof needs. Often a clear-out and a few refixed tiles are all it takes. Our answer on repairs during roof cleaning explains why checking while we are up there saves a second visit, and the roof cleaning and moss removal page shows the rest of the work. Ring 01793 626096 or use the enquiry form.