HELP!! wet roof timber
- Thread starter dougiem
- Start date
Sorry to hear your problems ...another "invention" -breathing felt- fails Sponsored Links
A vapour check is installed on the warm side of the insulation. This would limit the migration of warm moisture laden air that would otherwise pass into the cold roofspace causing the laden air to condense. The installation is only feasible in a new build or an entire house strip and refurb. The point I'm trying to make is that these "breathables" are sold as a problem solver. Dig a little deeper you find that for them to function as described, detailing and workmanship have to be perfect. I used to make a living at roofing - it doesn't happen and these guys who design these systems should try getting their hands dirty. Sorry to rant, but I was the one who got the phone calls complaining about damp timbers and damp insulation.
Great that you can get eaves ventilation in. Ensure this gives you a clear airway into the roofspace and over the top of the existing insulation. Check that the ridge is actually providing ventilation, if not there are vents on the market that are in-line. Try googling Glidevale, Hambleside Danelaw, Klober or Cembrit. I've dealt with all these companies and all have a good range of ventilation products. Check out their recommended details for the positioning of vents to achieve what I've been trying to describe, they're done very clearly using graphics.
Even getting the ventilation right, you're still going to have to limit the amount of air passing from the living area into the roofspace. Seal around any pipes, conduits and light fittings that pass through into the roofspace using silicone. Use a compressible seal around the loft hatch and install a locking mechanism to pull the loft hatch door down onto the seal.
Installing EPS (expanded polystyrene?) between the rafters and leaving the ventilation as is, might allow the roofspace to warm up a bit and so allow the air to hold more moisture, but remember you're going to have cold air entering the roofspace at low level probably on the wrong side of the insulation between the rafters. Again have a look at the companies already mentioned, they'll show detailing of how to ventilate when the insulation follows the rafter.
Great that you can get eaves ventilation in. Ensure this gives you a clear airway into the roofspace and over the top of the existing insulation. Check that the ridge is actually providing ventilation, if not there are vents on the market that are in-line. Try googling Glidevale, Hambleside Danelaw, Klober or Cembrit. I've dealt with all these companies and all have a good range of ventilation products. Check out their recommended details for the positioning of vents to achieve what I've been trying to describe, they're done very clearly using graphics.
Even getting the ventilation right, you're still going to have to limit the amount of air passing from the living area into the roofspace. Seal around any pipes, conduits and light fittings that pass through into the roofspace using silicone. Use a compressible seal around the loft hatch and install a locking mechanism to pull the loft hatch door down onto the seal.
Installing EPS (expanded polystyrene?) between the rafters and leaving the ventilation as is, might allow the roofspace to warm up a bit and so allow the air to hold more moisture, but remember you're going to have cold air entering the roofspace at low level probably on the wrong side of the insulation between the rafters. Again have a look at the companies already mentioned, they'll show detailing of how to ventilate when the insulation follows the rafter.
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