condenstation on one half of loft space felt.......

F_Bear

background: 1995 3 bed semi, pitched roof with boarded out loft space, cavity wall insulation and poorly fitted double glazing.

went up into the loft to get the xmas decorations out and noticed 1 half of the pitched roof had water drips on it. the other half was dry. the half that has water drips on it is above the main bedroom.

been in the house for 6 years and never noticed this; had cavity wall insulation for 4+ years. we keep the house about 20degres when we're in, and the loft only has 2-3 inches insulation.

im thinking the heat is leaking into the roof then condensing but why only on 1 side of the loft space; and how can i fix it?

tony6403

Would be better if you could improve your loft insulation but when boarded can be a pain.
Is the moisture above the loft hatch? If so insulate the hatch door and make sure it is well sealed to prevent warm air getting into the loft space.

keystone

Check that you don't have too much insulation in the loft and that the eaves of the part that is getting the condensation haven't been blocked up solid with the wretched stuff thus impeding natural ventilation across the loft soffit to soffit.

Cheers

dodgydl

Had a similar issue and its usually the south facing roof on your house that has no condensation and the north facing roof that does.
As others say, check your loft hatch and make sure it is tight fitting (with no gaps - install a door or window seal if you do not have one) and make sure the hatch is insulated.
Also make sure you have some airflow up in your loft. With no airflow there is nowhere for the warm air to vent.
A lot of people have this same issue and there are many things you can do to try to avoid it. Google "condensation in loft space" and you will find many threads from different message boards talking about it with suggestions you can try.

spannerzone

There isn't a bathroom ceiling extractor fan installed that goes into the loft across then outside maybe come lose or broken, venting bathroom steam into the loft?

F_Bear

Had a similar issue and its usually the south facing roof on your house that has no condensation and the north facing roof that does.

thats right! is this because the sun is heating the south side?

theres no extraction fans or anything goin into the loft, just the hot water tank up there.

Johnandabby

F_Bear wrote: »

thats right! is this because the sun is heating the south side?

theres no extraction fans or anything goin into the loft, just the hot water tank up there.

You are likely to be getting condensation due to poor ventilation - this could be made worse by heat from the hot water and/or poor insulation between the loft and the house, but the ventilation is the key to resolving the issue. Most houses have a sunny side, so I think that's a red herring - it also doesn't have a solution!

You need to check the ventilation at all sides of the roof, but start with the side that has the condensation. You need cross ventilation across the roof to clear any condensation.

Is the hot water cylinder well insulated? If not, think about doing so as a well ventilated roof space will be condensation free but colder, and therefore improved insulation will always help.

The_Economist

Ventilation is always going to be the answer. Heat rises so when it hits the cold its instant moisture. It's a pain in the a$$e to get rid off.