Roof leak or condensation?

[GraPC]

Hi,

I posted this earlier today but I think it wasn’t in the correct forum.

I’m trying to find out if we have a roof leak or if the issue is condensation. We have had issues with condensation in the loft space previously and had tile vents fitted and it seems to have cleared this up.

The issue we’re still having is that a few sections of the roof beams are still getting wet but it seems to be at random times. Some mornings it will be dry and then wet later that day. Some times it will be wet during rain but then dry the next morning, some times it will be dry when raining and then wet the next day. When I say wet, it’s not soaking but more cold and damp to the touch. We’ve had the company that fitted the roof back numerous times and they can’t find a leak, we’ve had a second opinion and they can’t find a leak either.

I was wondering if rainy weather is causing high moisture levels which is being drawn in by the vents and then this is making the beams feel damp? Is that possible? Water is not dripping anywhere that I can see but the beams feel damp to the touch.

Is it possible that having vents fitted is making the loft colder and causing these sections to feel damp at times?

Yesterday was torrential rain all day and they felt damp when I got home from work but by the evening they’d nearly dried. If it was a leak would the wood dry that quickly?

Sorry for all the questions and long post.

Thanks

 

[datarebal]

Vents will make the loft cooler.
Have you plenty of insulation at ceiling level?
Can you see water entering the loft ?

 

[harrythefurrysquid]

Sounds more like condensation to me, as humidity can change quite rapidly with temperature and weather.

Here's an idea:

Grab yourself a pair of bluetooth hygrometers.
Put one in the loft close to an affected area, and the other outside but protected from sun and rain.
You'll be able to get a temperature and humidity chart for each one on your phone.
The closer the loft temperature and humidity tracks the conditions outside, the better the ventilation.

If you find that the humidity stays stubbonly 90%+ in the loft when it's significantly lower outside, then you don't have sufficient ventilation.
If it drops but is delayed and doesn't go down as far as outside, then ventilation is maybe adequate but not ideal.

IMHO if the humidity levels are tracking reasonably well and regularly dip down to below 70% given <60% outside, you've probably done enough.

Side-benefit: you'll clearly be able to see whether the loft is heating up when you turn your heating on inside (insufficient insulation), and whether the humidity climbs when you're using the shower (insufficient seal around lights/hatch).

 

[GraPC]

Vents will make the loft cooler.
Have you plenty of insulation at ceiling level?
Can you see water entering the loft ?

Yeah we’ve got plenty of insulation up there and the eves are all clear. I’ve got 6 tile vents and a few of those manthorpe lap vents. It’s pretty much all cleared the condensation we were having. Several beams were wet and the felt had droplets on. There’s just these same sections of beams that sometimes feel damp to the touch.

I can’t see any water coming in and there’s never been any drips onto ceiling. No cracks on the tiles that I can see either.

As it was heavy rain all day yesterday and windy I thought it was a leak but if it’s not I wasn’t sure if the wet air from outside was being drawn into the loft space. The areas that are getting damp are right in the path of the air flow from the vents. When it’s windy you can feel the air blowing into these sections so I’m wondering if they are extra cold because of that and this is why they feel damp?

If it was a leak I would have thought the beams would be soaked and take a while to dry out but they were pretty much bone dry by the end of the day. I’ve been up now in the rain and they’re dry.

There’s no real consistency to when they’re damp or not that’s what’s confusing me.

 

[GraPC]

Sounds more like condensation to me, as humidity can change quite rapidly with temperature and weather.

Here's an idea:

Grab yourself a pair of bluetooth hygrometers.
Put one in the loft close to an affected area, and the other outside but protected from sun and rain.
You'll be able to get a temperature and humidity chart for each one on your phone.
The closer the loft temperature and humidity tracks the conditions outside, the better the ventilation.

If you find that the humidity stays stubbonly 90%+ in the loft when it's significantly lower outside, then you don't have sufficient ventilation.
If it drops but is delayed and doesn't go down as far as outside, then ventilation is maybe adequate but not ideal.

IMHO if the humidity levels are tracking reasonably well and regularly dip down to below 70% given <60% outside, you've probably done enough.

Side-benefit: you'll clearly be able to see whether the loft is heating up when you turn your heating on inside (insufficient insulation), and whether the humidity climbs when you're using the shower (insufficient seal around lights/hatch).

Thanks for the advice, I think I’ll give that a go.

Since having the vents fitted and sealing/insulating the hatch the loft is freezing so I thought that meant we’d sorted out the temp but if warm air is still getting in then these sections must be the coldest spots in the loft?

Thinking about it, the sections that get damp are where we had leaks in the old roof. The wood was saturated but fully dried out after getting them fixed. Now we’ve got a new roof but condensation seems to be an issue do you think that these sections of wood are prone to condensation having previously been wet or does that sound daft

 

[harrythefurrysquid]

Now we’ve got a new roof but condensation seems to be an issue do you think that these sections of wood are prone to condensation having previously been wet or does that sound daft

It could just be a particularly cold spot - which would make it both most likely to attract condensation, but also feel cold to the touch.

I guess you could try something like a wood moisture meter if you wanted to get some objective measurements.

 

[GraPC]

It could just be a particularly cold spot - which would make it both most likely to attract condensation, but also feel cold to the touch.

I guess you could try something like a wood moisture meter if you wanted to get some objective measurements.

That’s what I was thinking. Even when it’s dry it feels cold to touch. I’ll just have to keep an eye on it but I think me opening the loft up all the time probably isn’t helping!