Roof

LSainsbury · 24-12-2009, 16:15

Hi all,

Just been in the loft and discovered water droplets on the inside lining of our roof.

Is this condensation or is it water that got under the tiles from the snow etc?

Any advice on Christmas eve would be great to put my mind at rest!

Cheers
Lee

idi banashapan · 24-12-2009, 16:17

looks like condensation to me from the way it appears to be forming, but I'm not a roofer!

martyh · 24-12-2009, 16:18

Quote:

Originally Posted by LSainsbury

Hi all,

Just been in the loft and discovered water droplets on the inside lining of our roof.

Is this condensation or is it water that got under the tiles from the snow etc?

Any advice on Christmas eve would be great to put my mind at rest!

Cheers
Lee

probably condensation caused by the warm air from your house hitting the cold in the loft ,a leak would be localised in one spot

had a closer look and yes defo condensation ,i suspect you have snow on your roof ?

LSainsbury · 24-12-2009, 16:39

Quote:

Originally Posted by martyh

probably condensation caused by the warm air from your house hitting the cold in the loft ,a leak would be localised in one spot

had a closer look and yes defo condensation ,i suspect you have snow on your roof ?

As you say it's not localised - yes loads of snow which has now all melted away - well from the roofs at least...

DaiNasty · 24-12-2009, 16:43

Looks like normal consensation to me too. That's why you should never roll insulating felt right out tight to the eaves where the roof meets the ceiling. There should always be space for that condensation to roll down and exit outside the wall cavity. Insulating felt would trap it and eventually you could get a wet spot on a bedroom ceiling.

martyh · 24-12-2009, 16:47

Quote:

Originally Posted by DaiNasty

Looks like normal consensation to me too. That's why you should never roll insulating felt right out tight to the eaves where the roof meets the ceiling. There should always be space for that condensation to roll down and exit outside the wall cavity. Insulating felt would trap it and eventually you could get a wet spot on a bedroom ceiling.

quite correct ,it is also another reason to have ventilated soffits to prevent this kind of build up

**Rob** · 24-12-2009, 17:17

Definitely condensation.

Even with good ventilation at the eaves, it's not always enough. Yes insulation shouldn't be pushed right into the gaps, but you don't want to leave the edge exposed either otherwise you get all sorts of condensation problems around the top of the walls inside the house itself. The greater the thickness of insulation you have, the greater the risks of condensation. The absence of mildew on the timbers suggests it's not often a problem for you.

In many cases to get a good cross flow of air in lofts you need vents not only at the eaves but also near the ridge of roofs. Often you won't get a flow of air where there is little outside wind.

martyh · 24-12-2009, 18:24

Quote:

Originally Posted by Rob

Definitely condensation.

Even with good ventilation at the eaves, it's not always enough. Yes insulation shouldn't be pushed right into the gaps, but you don't want to leave the edge exposed either otherwise you get all sorts of condensation problems around the top of the walls inside the house itself. The greater the thickness of insulation you have, the greater the risks of condensation. The absence of mildew on the timbers suggests it's not often a problem for you.

In many cases to get a good cross flow of air in lofts you need vents not only at the eaves but also near the ridge of roofs. Often you won't get a flow of air where there is little outside wind.

also correct ,i have just finished working on a contract for gateshead council renewing roofs and all the ridges have ventilation along with the eaves to allow a good through draft in the loft space + we used breather felt under the tile

DaiNasty · 24-12-2009, 19:02

Quote:

Originally Posted by martyh

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also correct ,i have just finished working on a contract for gateshead council renewing roofs and all the ridges have ventilation along with the eaves to allow a good through draft in the loft space + we used breather felt under the tile

Not something I have to worry about on the top of the hill in Lincoln. Where my house stands now there used to be a row of windmills. Soffit ventilation is more than enough..