Damp patches on Roof Beams in Attic

Lewis_Benson · 10-01-2023 11:53PM #1

Hi Folks,

Bit of an odd one to me, as I am new to a Bungalow, and to add to that, a cottage type bungalow.

House is an old Land Commission house, likely built in the 30s or 40s, with an extension added abut 21 years ago, the problem is in the attic space in the extension.

While putting away the Christmas Decorations this evening I noticed what looks like damp/moisture in the attic, where the ceiling joists meet the roof beams. It seems to be on a lot of them, and is more prominent at the northerly end.

This is a cottage type bungalow as I have mentioned, so there is no Soffitt to speak of, the fascia is almost flush with the exterior wall. It doesn't feel really wet to the touch, just mildly damp, which is odd because looking at it you'd swear it was soaking.We have had a hell of a lot of rain in the midlands the last few weeks, and I am wondering if this could be the cause.

The plasterboard on the ceilings below are foil backed, and you can see there is insulation on the attic floor. There are no vents in the attic so no real ventilation.

Does this look like damp, or water ingress?

Thanks in advance for any info.

Lewis

The Continental Op · 11-01-2023 01:17AM

First things first. Think positive. The construction is 21 years old and there is no obvious sign of rot.

However I think it requires a bit of further investigation. You need to put in your diary to check it every couple of weeks and see if the damp remains.

You would normally expect some air flow from the outside up past that area of damp. What I might do is remove the insulation from a couple of those sections between the rafters and when you check back see if those areas are dry or drier than the ones that still have insulation stuffed around them.

With cold damp weather the felt will get damp on the inside with condensation and it looks like its running down the inside soaking into the insulation (is the insulation wet) and the ends of the rafters. This happening occasionally is no big deal but you don't want the ends of the rafters to stay wet/damp all the time.

Any idea when the insulation went in?

If there is some ventilation from where the soffit should be then Loft vent trays might help maintain the ventilation while allowing the maximum area of insulation https://klober.co.uk/roof-ventilation/eaves-roof-ventilation/p/loft-vent-tray

10-10-20 · 12-01-2023 12:37AM

I might be wrong, but I wonder if it's coming from the cavity, perhaps it wasn't closed off and that's the condensation at the point where the moist air hits the cold roof structure.

Pull back that insulation at the junction of the roof and ceiling and re-take some photos. See if you can focus on the part after where the foil-backed plasterboard terminates, ie, where the 2 in the images below appears.

dathi · 13-01-2023 03:43PM

is that not just brown wood preservative applied to the bottom of the joists? is the yellow glass fibre damp to touch

10-10-20 · 13-01-2023 04:27PM

https://www.boards.ie/discussion/comment/120103468#Comment_120103468

End-grain preservative, yes perhaps. Need clarification from the OP.

Lewis_Benson · 17-01-2023 01:20AM

Thanks for the replies folks.

I have not had an opportunity to get up and take another look in the last few days.

I'm going to go up tomorrow and Inspect further.

I did mean to mention that the walls wee pumped with bead insulation towards the end of last spring, could this have had any impact on what I am seeing?

I will let you all know tomorrow if the fiberglass Insulation is wet.

bfclancy2 · 17-01-2023 09:27AM

check your gutters, blocked gutters are the most common cause of issues like this from my experience

C. Eastwood · 17-01-2023 10:10AM

https://www.boards.ie/discussion/comment/120118579#Comment_120118579

It is impossible for blocked gutters to have any impact whatsoever with surface condensation.

The Continental Op · 17-01-2023 10:37AM

https://www.boards.ie/discussion/comment/120118302#Comment_120118302

Good time to check with the temperatures getting low again, but don't forget to compare the conditions when we get warmer weather.

TimHorton · 17-01-2023 11:41AM

https://www.boards.ie/discussion/comment/120118693#Comment_120118693

Maybe it's not condensation but rainwater wicking up via felt/timber from blocked gutter ?

TimHorton · 17-01-2023 11:48AM

https://www.boards.ie/discussion/2058279083/damp-patches-on-roof-beams-in-attic

Also there looks like there is no ventilation gap for the soffit vents to work!

C. Eastwood · 17-01-2023 12:13PM

https://www.boards.ie/discussion/comment/120119106#Comment_120119106

That is an impossibility.

C. Eastwood · 17-01-2023 12:15PM

https://www.boards.ie/discussion/comment/120119134#Comment_120119134

If there are sufficient soffit vents then the Surface Condensation would not occur.

TimHorton · 17-01-2023 12:39PM

https://www.boards.ie/discussion/comment/120119269#Comment_120119269

Looks like the eaves are completely blocked with insulation.

10-10-20 · 17-01-2023 01:08PM

https://www.boards.ie/discussion/comment/120119392#Comment_120119392

Yes, but seems to be a thing with the design of this:

"This is a cottage type bungalow as I have mentioned, so there is no Soffitt to speak of, the fascia is almost flush with the exterior wall. It doesn't feel really wet to the touch, just mildly damp, which is odd because looking at it you'd swear it was soaking.We have had a hell of a lot of rain in the midlands the last few weeks, and I am wondering if this could be the cause."

chooseusername · 17-01-2023 03:30PM

That doesn't look like condensation to me. The felt looks like bitumen and looks dry.

If there was condensation forming on the felt it would be obvious on the the tops of the rafters, and would be dripping off before it reached the eaves.

OP is there any water dripping from the felt onto anything you have stored up there?

from another post;

https://www.boards.ie/discussion/2058276461/attic-condensation-droplets-on-the-felt

C. Eastwood · 17-01-2023 04:54PM

https://www.boards.ie/discussion/comment/120119392#Comment_120119392

any Photos from inside in the Attic void and photos of the Facsia and eaves and roof coverings.

chooseusername · 17-01-2023 06:00PM

If there is no soffit, then there's no overhang at the eaves, so the fascia board is probably fixed directly to the rafter tails or joists and flush with the wall.

If the roof tiles and felt are not discharging into the gutters properly, the fascia board will wick water back to the rafters, joists and probably the wall plate.

A simple fix is remove the bottom 3 or 4 roof tiles and insert new felt up under existing felt and lap it out over the fascia board.

TimHorton · 18-01-2023 10:34AM

https://www.boards.ie/discussion/comment/120121029#Comment_120121029

BTW Clint claims what you suggest is "Impossible" !

chooseusername · 18-01-2023 10:47AM

https://www.boards.ie/discussion/comment/120123548#Comment_120123548

Oh, I must be wrong so!

bfclancy2 · 18-01-2023 05:28PM

https://www.boards.ie/discussion/comment/120118693#Comment_120118693

i see no condensation in any of the images, have often seen water on roof trusses / rafters due to blocked gutters and have rectified such issues by a simple cleaning of the gutters and removing blockages, please stop pretending you know what you are talking about, its tiresome

Lewis_Benson · 24-01-2023 05:58PM

Hi folks,

Just an update, was up there today putting the last of the Christmas stuff away.

Had a good poke around several of the joists near the edges, no wetness anywhere on the fiberglass and the timbers are dry.

Lifted back the fiberglass over the outside walls and bone dry, foilback plasterboard goes all the way to the edges and is dry too.

Panic over.

Thanks everyone for the replies on thread.

maudiemcc · 03-01-2025 06:46PM

Hi,

I know I’m late to the thread. But what was the cause / solution?
I think I have the same problem.

Thanks in advance!

10-10-20 · 03-01-2025 06:56PM

https://www.boards.ie/discussion/comment/123013744#Comment_123013744

It's literally just one post above your question.

mikehammer.. · 03-01-2025 07:09PM

What was the problem here

10-10-20 · 03-01-2025 07:46PM

https://www.boards.ie/discussion/comment/123013843#Comment_123013843

Sheesh - it's literally at the top of the page.

😁

Lewis_Benson · 04-01-2025 04:44AM

There was no problem.

GreeBo · 07-01-2025 02:34PM

I assume that this is just preservative on the timbers and they are dry, but to be fair its unclear from the last post if the timbers are still stained or not.

For anyone else reading the thread in future, it can be helpful in this situation, to mark the outline of the "water mark" and then check it a couple of days/weeks later so see if its changed. Some staining can occur during the installation for example and might never be wet again.

Damp patches on Roof Beams in Attic

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