Damp and water in walls in loft

cms72

We purchased a Persimmon home in September 2018.  In September 2021 we were getting mould in my sons room and then water started to come into the corner of the wall.  I contacted Persimmon who tried to extracate themselves on the grounds that it was over 3 years old but we stood firm and explained this was a problem with the build.  Their customer care department visited and their explanation was nothing short of ridiculous citing that it was bone dry in the loft and it could be caused by condensation, advising us not to open the roof hatch as even steam from a kettle could cause problems?!  He advised he would send a roofer to check the external property and after reminding them several times they did.  The roofer could not find anything on the roof but asked to look in the loft and advised us that the walls were absolutely saturated along with the trusses and he also noticed insulation stuffed into the eaves which he said he had not seen before.  He advised us to seek further advice from the site manager which I did and he inspected the property and confirmed the same issues.  A worker who he brought along had already mentioned that there could be insulation in the eaves which he had seen on previous developments and said this does cause issues.  I have done some internet research and someone had posted on this site in 2017 with the same problems and advised that they had stopped building the particular type of house that they lived in but did not post any outcome so I was hoping there may be others who could possibly advise from here.  I intend to write to Persimmon with all of the details and request that they come to some solution, the roofer did mention that there may not be enough airflow but would this really cause it to soak through to an internal wall?  Any advice would be greatly received, I don't have any experience of these issues and would be grateful if anyone has any information that may be useful.  I also intend to speak to the building inspector who signed the house off as clearly this should have been flagged, my neighbour has also had issues and they discovered when having recent building work done that Persimmon had failed to insulate the house correctly.

donemedosh

If warm air is entering your loft this mixes with cold air = condensation. So insulation looks to be an issue. Plus if neighbours have same type of problem, check if others in your estate have issues as well. House builders are never too helpfull once they have sold the house. So if you can get others who have same issue then you have a loader voice.

cms72

The problem is the neighbours have issues with their damp course, they say their loft area is fine but then they don't have the insulation in the eaves.  They have got problems with mould on the ceilings but they have just been cleaning this themselves.  I will pursue Persimmon for the time being as the photographic evidence I have speaks for itself. Thanks for your input, it's much appreciated.

Doozergirl

The eaves should be free of insulation.  It's important for your loft to be cold and draughty.  As above, if someone has insulated the eaves so that they can't
breathe, then the result is what you have - a lot of condensation.

Clear the eaves of the insulation and hopefully things will (return to) be normal and no rot has had time to set into the roof timbers.  

grumbler

donemedosh said:

If warm air is entering your loft this mixes with cold air = condensation.

If warm air is entering your loft, stop it entering. Seal the most obvious ways -  loft hatch and the light fittings.

cms72

Not sure if condensation could cause this.

canaldumidi

Seal what you like (and it's certainly sensible to do so), but you'll never prevent all the warm air rising into the loft. And as explained, when that hits cold ait, condensation will form, and in time willcause damp walls and then eventually, the damp will run down and cause damp in the bedroom walls.

A flow of fresh air is essential in an attic, especially a well-insulated one. There are special roof tiles you can get which allow ventilation, and you could put in lap vents or vents into the fascia boards.

But normally, by leaving an insulation gap under the eaves there is sufficient air flow from under the eaves with the air flowing above the insulation. That's why all instructions for installing insulation tell you not to push the insulation right up under the eaves!

If that is indeed the problem,it's an easy DIY solution, and in time the damp will dry out.

3 years, so hopefully there's been no damage to woodwork .........

grumbler

canaldumidi said:

Seal what you like (and it's certainly sensible to do so), but you'll never prevent all the warm air rising into the loft.

Well, we are talking about big amounts of water that need big amounts of air to carry it. Of course, the loft needs ventilation, but  the bigger amount of air gets to the loft  from the house, the better ventilation is needed.