Question answered
Gap between the roof and the gutter
The short answer
A gap between the roof and the gutter lets water run behind it onto the fascia and into the eaves. The fix is to make the roof covering deliver into the gutter: lap the eaves felt or an eaves tray over the fascia edge, set the tiles to overhang the gutter by the right amount, and refit the gutter at the right height, without blocking the eaves ventilation.
If rain runs down the back of your gutter and onto the fascia, the roof edge is not delivering water into it. The cause is usually the felt, the tile overhang or a gutter set too low or too far out.
How water gets behind a gutter
A roof sheds water from its lowest course of tiles or slates. Those tiles should overhang the gutter, so that water drops into the middle of it. When the tiles stop short, or the gutter has slipped or been fixed too far out, water slides under the tile edge and runs down the back of the gutter instead.
That wets the fascia from behind, which is the part you cannot see from the ground. Over time the board rots from the inside, the gutter brackets pull out, and moisture reaches the rafter feet and the wall plate. A damp patch inside, close to the ceiling edge, is often the first sign.
The same fault appears when the old gutter has been replaced with a different profile at a different height. A new gutter that sits half a centimetre too low or too far away from the edge can undo years of working drainage. Our note on cast iron gutters explains why old runs were fixed as they were.
The eaves felt and the drip tray
Below the tiles sits the underlay, the sheet that catches any water getting past the covering. At the eaves it should not simply stop at the fascia edge. It needs to run over the top of the fascia, or into an eaves tray, so that anything reaching it is carried forward into the gutter, not down the back of the board.
An eaves tray, sometimes called a drip tray or eaves support tray, is a rigid strip that holds the felt in a gentle curve and also supports the first course of tiles. Where there is none, felt can sag, hold water, rot and drip behind the board. On many older houses the felt was cut short or has perished, and the gap has been there for decades.
Repairing it means lifting the bottom courses of tiles or slates, fitting a tray or relapping the felt over the fascia, and refixing the covering. It is a modest job when done together with new boards or gutters, and a nuisance on its own.
Do not block the ventilation to cure the gap
A tempting fix is to stuff or seal the space under the first course. That can choke the air path into the loft. Marley's guidance on BS 5250 says that for a cold roof with HR underlay, eaves ventilation of 25 mm along the length of the eaves is needed for pitches of 15° or less, and 10 mm for pitches more than 15°.
A roof with an LR underlay and a well-sealed ceiling may rely on the 3 mm of normal eaves construction, provided its third-party certification requirements are fully met. Which applies to your roof depends on the underlay and the pitch, so ask, and check before changing the eaves.
A repair that keeps rain out of the gap but starves the loft of air swaps a leak for condensation. A good fitter protects both: the drip path and the vent path. If you see black spots on rafters, treat it as a related problem rather than a separate one.
The wider roofline work we do around the eaves, from boards to downpipes, is described on our gutters, soffits and fascias page.
Height, projection and fall of the gutter itself
The gutter has to sit so that the edge of the roof covering projects over its centre. If the projection is too short, water sheets down the back. If too long, it can overshoot the front in a downpour. Getting this right is a matter of the bracket arm, the board and the fall.
Brett Martin suggests a fall of 1 mm in every 600 mm, and brackets no more than 900 mm apart. If the board has twisted or the brackets have sunk, the gutter may no longer be where it was set. Our page on gutter damage and insurance covers what to do if a storm has caused it.
Where we find a gap, we photograph the eaves from the ladder, show you the line of the felt and tiles above the gutter, and describe the repair in the written quote, which follows the survey as one total price.
Signs you have a gap, and what to look at
Watch the gutter in heavy rain from a safe position. Water trickling down behind it, or running down the fascia in streaks, shows the problem. Dark staining or lines on the fascia, or green growth on the back of the board, tell the same story. Inside, look for a damp line along the top of the outside walls, particularly under the eaves.
If the gap is the cause of a leak around a joint, the two faults often sit side by side, so read about a leaking gutter joint as well. If the board is already soft, consider the points in fascia capping over old timber before covering it.
The gap behind the gutter: two quick questions
Can I just push the gutter closer to the roof?
Sometimes, if there is room and the board is sound, but moving it can leave the fall wrong or the tiles hitting the gutter. We check the felt, the overhang and the fall together. Moving a bracket without checking the rest often shifts the leak rather than curing it.
Is a gap behind the gutter an emergency?
Not usually, but it does get worse the longer it runs. Water behind the gutter rots the board and can reach the rafter ends. If you see damp inside, or a board dropping, we prioritise the job and make the roof safe first. A survey shows how far it has gone.
Tell us about your roof
Describe what is happening and we will call you back to arrange a visit.
- Photographs of what we find
- A written quote with one total price
- Or call 01903 299063
10-year workmanship guarantee, in writing.