Sorry, this is a long one.
Moved into a detached bungalow a year ago (last winter). The loft is about 50ft long, with gable at each end and ridge height about 10ft. Most of the loft is double layer insulation. 99% of the liner is bitumous, with the rest breathable. All in good condition. There was a certificate dating back 12 yrs for the insulation stapled to a support right by the loft hatch. The insulation was pushed right into the eves.
There were no soffit vents, and the old wooden soffits and fascias has been over pvc'd. The water tanks had been removed 6 yrs earlier when a combi had been fitted. An extractor duct ran about 5ft from the bathroom ceiling to the soffit. The extractor was non functioning.
The previous occupants, tennants, had not been into the loft, ever, during their 12 yr tenancy.
Part of my requirement when moving in was to board the loft as I was moving from a much bigger house so needed the storage. Although I never tested the humidity, it felt a little damp. But never smelled damp. And no sign of condensation.
I cross-battoned and boarded 75% of the loft floor for long term but possibly temporary hoarding space. Trying to do the right thing, I added 20 70mm soffit vents along each side, so 40 in total, and cleared all insulation from the soffits. Also added a short piece of 20mm plastic conduit into each lap of the liner to open up an air flow.... over 200 of them. Even in a light breeze, the draught up there was huge.
Also fitted a new extractor to the existing bathroom duct.
One winter on and it's all gone mouldy. Anything up there with a hard shiny surface is visibly wet. Any cardboard boxes are soft, and any fabrics have gone mouldy. The air belting through even feels wet. It's freezing up there.
There's no leaks from the bathroom extractor ducting. But, the loft hatch in the hallway is not a great seal. Was much better before I added a loft ladder and put a hinge on the lid.
One thing I've discovered, which is obviously wrong (and my fault).... the extraction is out through the soffit, and a foot to the left and fight of this outlet is a soffit vent which I now think is allowing the steam straight into the loft. There are 3 of us here, so that means 2 showers and 1 bath minimum, every day, with the extractor on during the event and for at least an hour after.
So, finally, some questions...
1. Is the poor sealing loft hatch, and the extractor / soffit vent balls-up enough to give me damp issues that were not there previous?
2. Is it possible to have too much ventilation? Surely if the outside air is wet, inviting it straight in, lots of it, can't be good.
Please give me the benefit of your knowledge.
Thank you.
Ropi
Moved into a detached bungalow a year ago (last winter). The loft is about 50ft long, with gable at each end and ridge height about 10ft. Most of the loft is double layer insulation. 99% of the liner is bitumous, with the rest breathable. All in good condition. There was a certificate dating back 12 yrs for the insulation stapled to a support right by the loft hatch. The insulation was pushed right into the eves.
There were no soffit vents, and the old wooden soffits and fascias has been over pvc'd. The water tanks had been removed 6 yrs earlier when a combi had been fitted. An extractor duct ran about 5ft from the bathroom ceiling to the soffit. The extractor was non functioning.
The previous occupants, tennants, had not been into the loft, ever, during their 12 yr tenancy.
Part of my requirement when moving in was to board the loft as I was moving from a much bigger house so needed the storage. Although I never tested the humidity, it felt a little damp. But never smelled damp. And no sign of condensation.
I cross-battoned and boarded 75% of the loft floor for long term but possibly temporary hoarding space. Trying to do the right thing, I added 20 70mm soffit vents along each side, so 40 in total, and cleared all insulation from the soffits. Also added a short piece of 20mm plastic conduit into each lap of the liner to open up an air flow.... over 200 of them. Even in a light breeze, the draught up there was huge.
Also fitted a new extractor to the existing bathroom duct.
One winter on and it's all gone mouldy. Anything up there with a hard shiny surface is visibly wet. Any cardboard boxes are soft, and any fabrics have gone mouldy. The air belting through even feels wet. It's freezing up there.
There's no leaks from the bathroom extractor ducting. But, the loft hatch in the hallway is not a great seal. Was much better before I added a loft ladder and put a hinge on the lid.
One thing I've discovered, which is obviously wrong (and my fault).... the extraction is out through the soffit, and a foot to the left and fight of this outlet is a soffit vent which I now think is allowing the steam straight into the loft. There are 3 of us here, so that means 2 showers and 1 bath minimum, every day, with the extractor on during the event and for at least an hour after.
So, finally, some questions...
1. Is the poor sealing loft hatch, and the extractor / soffit vent balls-up enough to give me damp issues that were not there previous?
2. Is it possible to have too much ventilation? Surely if the outside air is wet, inviting it straight in, lots of it, can't be good.
Please give me the benefit of your knowledge.
Thank you.
Ropi
