Bungalow Roofing Guide
Bungalow Loft Condensation: The Leak That Isn’t a Leak
A surprising share of the “roof leaks” we are called to on inland Merseyside bungalows — Maghull, Lydiate, Aintree, Thornton, Kirkby, the Liverpool suburbs — are not leaks. The roof is dry. The loft is wet. The water on the bedroom ceiling came from inside the house, went up through the ceiling as vapour, condensed on the cold underside of the roof and dripped back down.
Why bungalows suffer more than houses
Three reasons, and they compound.
- Every room is under the loft. In a house, the loft sits over the bedrooms. In a bungalow it sits over the kitchen, the bathroom, the living room and the bedrooms — every source of moisture in the home feeds straight up into one roof space.
- The loft is big and cold. A low pitch over a wide plan makes a large volume of air with a great deal of cold roof surface for vapour to condense on.
- It was never ventilated. 1960s bungalows had no eaves vents. The roof breathed through the gaps in the tiles and the bitumen felt. Then, over the years, the felt was replaced, the eaves were boxed in with new fascias, and 270mm of loft insulation went down — excellent for the heating bill, and it made the loft colder still. The moisture has nowhere to go.
How to tell condensation from a leak
| Condensation | Roof leak | |
|---|---|---|
| When | Cold, still weather; winter mornings | During and after rain |
| Where | Widespread; several rooms; often the coldest corners | One place, under the fault |
| Loft | Droplets on the underside of the underlay; damp across the whole slope; mould on rafters | A wet track from one point downwards |
| Roof outside | Nothing wrong | A slipped tile, failed mortar, a flashing |
If the ceiling stains are worst in January and the roof looks fine from outside, it is condensation until proved otherwise.
The fix that works
Ventilation, sized for the loft volume. Not a dehumidifier, not a “breathable” paint, and not more insulation. The roof space needs a continuous flow of outside air across it — in at the eaves, out at the ridge — so that vapour is carried away before it condenses.
- Eaves ventilation. Over-fascia vents or soffit vents along both eaves, with rafter trays to keep the insulation from blocking them. On most bungalows this is fitted from a ladder in a day without touching the tiles.
- Ridge ventilation. Vent tiles near the ridge or a ventilated dry ridge system, giving the air somewhere to leave. Fitted from a tower on a bungalow; built in as standard when we re-roof.
- Bathroom and kitchen extraction. Ducted to the outside, never into the loft. We find a surprising number of extractor fans venting straight into the roof space.
- Loft hatch seal. A loose hatch is a chimney for warm, wet air. A draught-sealed, insulated hatch is a cheap win.
When it really is a leak as well
Old bungalows can have both. Failed ridge mortar lets rain in and lack of ventilation keeps the loft wet. We inspect the loft and the roof together at the free inspection and tell you which is which, with photos. Our bungalow repairs page covers the roof side; our insulation service covers the loft — and we never fit spray foam, which turns a condensation problem into a rotten-rafter problem.
Questions we get asked
Why did my bungalow loft get damp after I added insulation?
Because the insulation made the loft colder without adding ventilation. Warm, moist air from the rooms still rises into the loft, meets a colder roof surface than before, and condenses. The insulation is not the problem; the missing ventilation is. Eaves and ridge vents fix it.
Can condensation damage the roof?
Yes, over time. Persistent condensation rots rafters and battens, rusts tile nails and saturates the insulation, which then stops working. It also produces mould, which is a health issue as well as a roof one.
How much ventilation does a bungalow loft need?
The Building Regulations guidance is a continuous 10mm gap at the eaves for a pitched roof over 15 degrees, plus 5mm at the ridge where the insulation is at ceiling level. In practice that means over-fascia or soffit vents along both eaves and ridge or tile vents. We size it to the loft at the inspection.
Will a roofer or an insulation company fix this?
It is roofing work: eaves vents, rafter trays, ridge and tile vents are fitted from outside on the roof. We do both the ventilation and the loft insulation, so the two are designed together rather than one undoing the other.
Not sure what your roof needs?
We offer free inspections across Merseyside. We go up, take photos, show you what we find and give you an honest recommendation. No pressure, no obligation.