Condensation in loft

[Hotwire]

I have recently had the insulation in my loft upgraded and now there is a lot of condensation forming on the roof felt. I have not noticed this before the upgrade, is it normal.

 

[JohnD]

same reply as //www.diynot.com/forums/viewtopic.php?t=116074

 

[gasmick2]

sounds like it now needs ventilating get it done soon or it will rot the rafters and etc
it needs air vents to the gable end or to the soffits both sides

 

[toptinker]

yes i got same problem but only on the north facing roof ?

 

[Hotwire]

Ok, first off thanks for the replies and let me say at the moment i am unable to climb the loft ladder and get into it. My 19yr old son has been up and told me off the condensation and i have seen it through the open loft door. Here is some more info about the loft:

The gable end has a vent through the wall, maybe about 8" or 10" square.

At the same time as the loft insulation was upgraded, cavity wall insulation was installed.

There is an inline extractor fan from the bathroom which has flexible ducting to an outside wall, the ducting is under a yard in length total.

 

[topgazza]

North facing is just plain colder so is prone to more condensation.

Key..as gasmick2 points out are air vents if it continues. I had some installed as part of the loft conversion I had done 4 years ago. I did ask the builder why and he said regs....to stop condensation. Obviously with the conversion the roof is no longer accessible.

 

[Hotwire]

Yes the condensation appears to be forming only on the felt of the north facing roof tiles. Never had this problem before the extra fibreglass and the cavity wall insulation. I am going to contact the firm who done the work after the new year holiday is over and see what they have to say on the problem.

 

[JohnD]

they will say you need more ventilation. If you can get your son into the loft ask him to see if the insulation has been unrolled into the eaves and blocks any air gaps there. Otherwise a vent at each end of the loft will allow airflow. You need a gap that fresh air can enter through, if you just have an exit, then it wil draw warm moist air from the house.

If uyou have any water tanks in the loft check that they have tight-fitting plastic lids and are cold, not warm.

If you have any steam vents in the ceiling, usually caused by making holes for downlighters, then warm damp air will rise through them.

However if you are in the habit of draping wet washing about the house or on top of radiators, then you are responsible for the excess moisture.

 

[Hotwire]

Hi, i will get my son to take a look to see if any venting near the eaves has been blocked. He,s no builder though and there isnt much space round the eaves, plus the extra fiberglass covers the rafters so its a bit dangerous for the uninitiated. Its so frustrating not being able to do it myself.

they will say you need more ventilation

Would the loft now need more ventilation just by the fact of the extra fiberglass and cavity wall insulation, even if they havnt blocked any venting off.

 

[JohnD]

it's quite possible that the insulation has gone into the eaves and blocked some designed or accidental ventilation.

It should be easy to see this though, perhaps using a torch. It is possible to trim back fibreglass with a big pair of paperhangers scissors or a breadknife.

It's also possible that the condensation has been happening for many winters but you weren't previously aware of it.

What's the answer about water tanks, gaps in the ceilings and wet washing?

I know what you mean about not being able to climb into lofts

 

[Hotwire]

I would have got back sooner but my internet connection has been down. Now that the holidays are over, i will get my boy to take a look. I would have noticed the condensation in previous years as the Christmas decorations are stored up there. I think you could be right about the ventilation in the eaves being blocked. The people who done the job were not the best workers i have seen. I will post back when i find the cause.

 

[Hotwire]

Just an update, someone came out from the insulation firm and agreed there was a condensation problem. I offered to show him pictures that had been taken when the condensation was there, but he said its ok i dont need to see them, this is a problem that sometimes occurs. He spent quite some time in the loft and on coming down said there was a little bit of blockage in the eaves which he had cleared. He said he didnt think it was the cause of the problem though. He then said would i be ok with him putting some battens down under the felt to see if this would cure the airflow problem. If it didnt he said extra vens who have to be installed. I said ok , as long as it was not going to cause any damage. He said it wouldnt, after he had finished he showed me what he had done. He had pushed battens down under the felt and the edges were visible about mid-roof sticking out from the felt. There now seemed to be an improved airflow. This was done during the high winds we had in Jan one thing i noticed was the was more noise than usual coming from the loft/roof area during these winds. A couple of days later i opened the loft hatch to see if all was ok the ends of the wood that were visible had disappeared but there was still airflow. Anyone have any views on this.

 

[JohnD]

a photo would really help

I would have been more inclined to cut back the fibreglass a bit to prevent it flopping back into the eaves.

 

[Hotwire]

There is nothing to photograph, as i said the wood disappeared. I will have another look tomorrow and take some pics through the open loft hatch. Its a nuiseance not being able to get in the loft myself.

 

[JohnD]

I know