Moisture Issue in Loft New Build

[Grzyb]

Maybe a stupid question, but you have checked that the extractor vent from the bathroom does actually connect to the outside? The reason I ask is because when we bought a new build a good few years ago, we had condensation in the loft and we found the pipe connecting extractor to installed soffit vent wasn't actually connected at both ends and was underneath the insulation that had been laid on top. Reconnected, and the problem went away....

I was there yesterday & Noticed these in the Loft, I assume that one of these is the Extractor Fan, so was wondering what the 2nd Pipe is?? That seems to just stop in Mid-Air....??

 

[Alec_t]

2nd pipe looks like a soil pipe with air-admittance valve on top.

 

[Grzyb]

2nd pipe looks like a soil pipe with air-admittance valve on top.

Thanks...

 

[AngleEyes]

you mean, "air that has a high relative humidity at outside temperatures"

which becomes dry air "air that has a low relative humidity at indoor temperatures" as soon as it warms up, even though the number of water molecules has not changed.

which is why ventilating outdoor air into the house, and ventilating indoor air out of the house, reduces damp.

Yes, more or less, but I didn't think that BlueLoo would understand the physics, so I tried to avoid being too technical.
The salient point was that airtightness in itself does not preclude damp, and in some circumstances can facilitate it.

 

[BlueLoo]

Yes, more or less, but I didn't think that BlueLoo would understand the physics, so I tried to avoid being too technical.
The salient point was that airtightness in itself does not preclude damp, and in some circumstances can facilitate it.

My understanding of Physics is apparently much better than your understanding of English.

 

[BlueLoo]

I was there yesterday & Noticed these in the Loft, I assume that one of these is the Extractor Fan, so was wondering what the 2nd Pipe is?? That seems to just stop in Mid-Air....??

Is that a lap vent?

I've read various reports on them being unsatisfactory.
I was looking at using them previously, as i was in the same situation as you, but decided against them on further investigation.

Apparatus they choke the vent given that they open to the underside of the roof tiles. They also can be challenging for moisture as the damp air is pushed out between the tile and the membrane, not directly into the outside. Might explain some of your issues.

I spent some time last year researching this to fix the builders bodge i had which ultimately led to ceiling rot. I came to the conclusion that there really is only one correct way to vent outside if you don't have an external wall and thats via a proper roof tile/vent which i now have.

 

[AngleEyes]

My understanding of Physics is apparently much better than your understanding of English.

Is that a lap vent?
I've read various reports on them being unsatisfactory.
I was looking at using them previously, as i was in the same situation as you, but decided against them on further investigation.
Apparatus they choke the vent given that they open to the underside of the roof tiles. They also can be challenging for moisture as the damp air is pushed out between the tile and the membrane, not directly into the outside. Might explain some of your issues.

I spent some time last year researching this to fix the builders bodge i had which ultimately led to ceiling rot. I came to the conclusion that there really is only one correct way to vent outside if you don't have an external wall and thats via a proper roof tile/vent which i now have.

Apparently not.