Moisture in roof space

The_Bloody_Baron

Hello all.

I have been living in my house for 1.5 years (built approx 1997) and we are having some moisture issues in the roof space.
The attic was soaking wet when I went to retrieve the Christmas decorations. Since then I have dried the bulk of it with a small heater and have left the hatch open from upstairs landing into roof for extra ventilation.

Potential issues:
- Bathroom extractor fan ceased to work and extractor vent was partially detached (now reattached and new fan in and working)
- Drainage venting pipe stops in roof space and does not go external of the house. The bathroom was modernised and I am able to see where the old external venting pipe has been cut off, but the new venting pipe has not been reattached, thus ending in the roof space around 1 metre from old venting pipe.
- Recently had the property insulated as it was eligible for the government funded insulation scheme. (Note, all neighbours have had this done and are not having moisture issues).

To any plumbers or other experts, how important is it for the PVC drainage pipe to go external of the house?
Has anyone had trouble with incorrect insulation?
Unfortunately the site won't allow me to post pictures for you to see.

It should be noted that the roof space was fine last Christmas and again over the summer when I was last up. The only big difference since then has been the insulation. Although that doesn't mean to say that the moisture hadn't already began, but maybe I just failed to notice until it got to its worst.

Any help and advice is greatly appreciated.
Have a great Christmas.
B Baron

Aylesbury_Duck

The extractor vent pipe being detached stands out as the likely culprit. It sounds as if the very humid air from the bathroom has been funnelled directly into the roof space. In the recent cold weather it will have condensed on just about everything. Check that the insulation has been laid such that there is still airflow at the eaves, a common mistake is that it is laid right to the edges of the roof space and prevents the natural airflow that is meant to come through the eaves.

I'll leave others to comment on the drainage pipe because I don't know enough about best practice for those.

Norman_Castle

Is the drainage pipe the soil stack? These can emit water vapour and sewage smells. Fit a durgo valve.

daveyjp

Insulation is the likely culprit - ensure the soffits are clear - lazy fitters will simply roll insulation out to the full extent of the roofspace and not bother with detail.

Vent pipe needs a durgo valve.

J_B

What a friend of mine did ....

Under the tiles, locate the joints in the roofing felt.
Slide a small piece of wood (maybe ½inch?) into where the felt overlaps.
Continue at regular intervals to provide ventilation in your loft.

Davesnave

J_B wrote: »

What a friend of mine did ....

Under the tiles, locate the joints in the roofing felt.
Slide a small piece of wood (maybe ½inch?) into where the felt overlaps.
Continue at regular intervals to provide insulation in your loft.

Did you mean "ventilation?"

I can't see this insulating anything!

J_B

Davesnave wrote: »

Did you mean "ventilation?"

I can't see this insulating anything!

Indeed I meant ventilation .... will edit now ....