Most homeowners see roof ventilation and loft insulation as unrelated jobs, but they go hand in hand. The function of insulation is to keep warmth in the living space, while the function of roof ventilation is to allow the escape of moisture from the roof void. Get one right and the other cannot perform its function.
Why Insulation Matters
Heated air rises. Without insulation, much of the air in a loft can escape through the roof. The general recommendation in the UK is to install 270mm of mineral wool or rigid insulation. This improves comfort and reduces energy costs, and reduces the demand on your heating system.
The main issue happens when insulation gets pushed into the eaves. Blocking off the gaps where air should flow into the loft leaves the timbers damp and the whole space stagnant, which totally defeats the purpose of installing loft insulation in the first place.
What Ventilation Actually Does
Mundane daily tasks can actually release an impressive amount of water vapor. Taking a shower and doing laundry obviously add water vapor to the air, but what about cooking? Boiling water releases a large amount of water vapor. All of that water has to go somewhere. If it can’t escape the home, it builds up in the loft. Like in all other situations where moist air is released into the home, some of it makes its way into the loft. Without adequate ventilation, moisture condenses on cold surfaces like rafters and felt and the underside of tiles.
Condensation leads to mold, rot and rust. Eave, ridge, and tile vents help move air and damp up and away from the interior of the building.
Spotting the Warning Signs
Pay attention to dark spots on the ceiling of upper stories, musty smells in the attic, or water droplets on the underside of the roof covering. Moisture that has no place to go can cause paint to peel around the upper story windows.
Insulation that has been compressed against the roof boards is a good indicator it’s time to have a professional take a look. Same goes for if daylight is showing through the eaves.
Getting Both Right Together
A quality installer creates an air passage above the insulation at the eaves and uses plastic vent trays to hold the insulation in place. They confirm that bathroom and kitchen extractor fans are ducted to the outside, not to the loft.
When a roof is re-covered or a loft is converted, it’s possible that the roof’s ventilation is altered. This is usually done without any consideration as to the impact it may have on the roof’s insulation or whether it is ventilating correctly. A professional roofer is best placed to check this and advise if the roof’s insulation is performing optimally.
Proper insulation and ventilation work hand in hand to maintain the health of your roof and keep you comfortable. For questions about your loft, we offer free advice to all.