I have a problem with airflow in my roof and I want to sort out the issue with condensation in the new valley.
I know I need more loft insulation added in, but I want to get ventilation right while I can.
Am seeing condensation issues in the new front valley. Despite dry ridge fitted and breathable membrane added to improve airflow in this area (done when new valley fitted).
I have just realised that I have fitted Eurosoffit soffit boards, which are to be used on roof pitches up to 15˚. Now not sure how much use they are in terms of ventilation.
Either way, I need more ventilation, the question is how much, what type and where do I add it?
I can see there are ways to calculate mm2 of airflow, I think I have this right...
Roof pitch is 30˚
Main Roof (Ridge 7 meters long X roof space 7 meters wide)
So 7m x 1000 = 7,000mm long roof. So 7,000mm x 10mm = 70,000mm2 airflow required.
The Extension (Ridge 5 meters long X roof space 4 meters wide)
So 5m x 1000 = 5,000mm long roof. So 5,000mm x 10mm = 50,000mm2 airflow required.
Vented soffits fitted as follows:
Approx 5 meters in total on the main roof
Approx 6 meters in total on the extension
ASSUMPTIONS:
If I assume these Eurosoffit vents give 10,000mm2/m (this is not documented on supplier website so I am guessing here) this would mean:
Main Roof 70,000mm2 airflow required
Approx 5 meters of soffit fitted so 50,000mm2 provided by the soffit in area.
Additional 20,000mm2 airflow required
The Extension 50,000mm2 airflow required
Approx 5 meters of soffit fitted so 60,000mm2 provided by the soffit in area.
No additional airflow required
Are my assumptions/calculations correct? Have I got this all wrong?
Do you think/know if the soffit used would provide 10,000mm2/m airflow?
What would you add to provide better ventilation, am assuming tile vents in the immediate area as the condensation is quite bad? Lap vents elsewhere to beef them up?
I know I need more loft insulation added in, but I want to get ventilation right while I can.
Am seeing condensation issues in the new front valley. Despite dry ridge fitted and breathable membrane added to improve airflow in this area (done when new valley fitted).
I have just realised that I have fitted Eurosoffit soffit boards, which are to be used on roof pitches up to 15˚. Now not sure how much use they are in terms of ventilation.
Either way, I need more ventilation, the question is how much, what type and where do I add it?
I can see there are ways to calculate mm2 of airflow, I think I have this right...
Roof pitch is 30˚
Main Roof (Ridge 7 meters long X roof space 7 meters wide)
So 7m x 1000 = 7,000mm long roof. So 7,000mm x 10mm = 70,000mm2 airflow required.
The Extension (Ridge 5 meters long X roof space 4 meters wide)
So 5m x 1000 = 5,000mm long roof. So 5,000mm x 10mm = 50,000mm2 airflow required.
Vented soffits fitted as follows:
Approx 5 meters in total on the main roof
Approx 6 meters in total on the extension
ASSUMPTIONS:
If I assume these Eurosoffit vents give 10,000mm2/m (this is not documented on supplier website so I am guessing here) this would mean:
Main Roof 70,000mm2 airflow required
Approx 5 meters of soffit fitted so 50,000mm2 provided by the soffit in area.
Additional 20,000mm2 airflow required
The Extension 50,000mm2 airflow required
Approx 5 meters of soffit fitted so 60,000mm2 provided by the soffit in area.
No additional airflow required
Are my assumptions/calculations correct? Have I got this all wrong?
Do you think/know if the soffit used would provide 10,000mm2/m airflow?
What would you add to provide better ventilation, am assuming tile vents in the immediate area as the condensation is quite bad? Lap vents elsewhere to beef them up?
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