Key Post: Attic Condensation

We moved into our new house in a small estate 3 yrs ago. We had a problem with condensation in the attic every winter including this year. The condensation gets so bad that it start to drip and damages the insulation. I have checked with the other residence in the estate but the do not have the same problem.

We contacted the builder each year and he has made slight adjustments (the vent from the ensuite shower now goes al the way out side and the attic entrance is insulated properly). All the while the builder was blaming the felt manufacturer.

My question to the forum is what can we do to fix the problem? Can we get someone else to fix the problem by getting a roof vent fitted(or something!) and get them to charge the original builder???

The current situation is that I rang the builder this morning and am awaiting reply.

Re: Attic Condensation

The fitting instructions for the attic insulation that I used, advised leaving a few inches gap where the insulation meets the eaves. This was to allow air to circulate in the attic to avoid issues like condensation. It would be worth checking to see whether your insulation is impeding any airflow near those edges.

Re: Attic Condensation

You may need to fit soffit and/or ridge vents to improve the airflow. A properly ventilated attic should feel as cold as though you're standing outdoors in wintertime.

Re: Attic Condensation

We've also had a problem with what we think is condensation and is also attic related.

On the ceiling of one bedroom, near the window, are round spots of mould - we've sanded them off, covered with damp seal and repainted and are wondering if there's a problem in the attic?

Doesn't condensation form where warm moist air meets a cold surface? Is it possible that the insulation in the attic is insufficient?

Re: Attic Condensation

Condensation in the attic is invariably down to inadequate (eaves) ventilation. As Askew70 suggests ensure that insulation does not block the airways at the eaves, either pull back the insulation slightly to leave a 50mm gap between insulation and sarking felt or tamp down with a broom to create the gap. Are vent grilles provided in the soffit and are there enough of them? Also ensure the tank is fitted with a proprietary lid (not airtight), I occasionally seen tanks where the lid wasn't fitted or was mislaid. Ensure no extract fans are venting directly into the roofspace! It shouldn't be necessary to include ridge vents in a simple roof with unobstructed eaves. This problem is easily solved but left unchecked can cause untold damage over time.

Re: Attic Condensation

the vent from the ensuite shower now goes al the way out side

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This would have been a major source of moisture in the attic before it was extended outside (this should have been picked up when the house was snagged).
The water vapour from the ensuite would now form in the pipe not the attic, but i have seen a house where a sag was left in the vent hose, and it filled up with water, about a litre, which then overflowed into the attic.

Re: Attic Condensation

I suppose that the insulation meant by the original poster is placed between the beams straight above the ceiling, not between the roof rafters. That would be cheaper for the builder to install.
The felt should indeed be breathable, letting moisture in the form of water vapour out of the house but not droplets of water into the house.
There is not much that can be done about it, except to change the felt which would be a major job. The original builder of the house is here the one to blame, it seems to be an major fault which could be putting the stability of the structure at risk. The timber could rot, mould could spread through the house and since the insulation – which is I suppose made from rock wool- gets wet the U values aren’t meeting the minimum demand. Most urgent: The plaster boards could come down, wet plaster board is dangerous when fixed at a ceiling.
If the house had been build to meet the building regulations than there would be a clear breach of the law. The contract of sale could be declared invalid.
The situation should be checked with an civil engineer who would take a sample of the felt and get it tested if it conforms with the relevant standard.

Re: Attic Condensation

The situation should be checked with an civil engineer who would take a sample of the felt and get it tested if it conforms with the relevant standard

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the felt is unlikely to be the problem re the condensation. Felt is a second line of defence from rain AFTER the slate / tiles.
The problem is either excessive moisture getting into the attic ( from the ensuite vent or similar) or the vents in the attic are not installed properly or blocked.

Re: Attic Condensation

Thanks for all that advice. The first thing I did 2 yrs ago was pull back the insulation. There are vents about every 4 feet. But it definitely isn’t cold up there. The builder says the same felt was used on all 8 houses I have spoken to the other 4 owners but they do not have the problem. The builder still owns the adjoining house and 2 others. The house is in a fairly sheltered location could this be a contributing factor?

Re: Attic Condensation

NiallA said:

the felt is unlikely to be the problem re the condensation. Felt is a second line of defence from rain AFTER the slate / tiles.
The problem is either excessive moisture getting into the attic ( from the ensuite vent or similar) or the vents in the attic are not installed properly or blocked.

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I have just snagged my house and from what I recollect, the extractor fan from the en-suite just pulls air into the attic. ie. there is no outlet pipe.

It never dawned on me that this could be a problem until reading this thread. Is this a breach of the building regs? Can I still make them put this right even though I didnt include it in my original snag list?

Re: Attic Condensation

Hi Sid,

As Carpenter says above it is very important to have this fixed. Others here might be able to confirm if it is in breach of building regs. You should definitely take it up with the builder even if you have already done your snag list.

Re: Attic Condensation

Hi I was surfing arround looking for answers & saw this post...
(perfect place to ask my question)

I'm currently buying a dormer bungalow with 2 bedrooms & a small bathroom in the roofspace. I've just done my snag list (I got a surveyor in cos I wasn't sure of the builder) and he has told me that there is no vapour barrier...
Basically the builder has used ordinary plasterboard nailled to the timbers & has packed far too much fiberglass type insulation in the roof space & hasn't maintained the required 50mm gap.
I'm fairly sure that the 50mm is no problem as the excess could just be removed but I don't know how he's going to remedy the lack of vapour barrier issue...

Is there any way he will be able to fix this without having to pull off all the plasterboard... for example can he apply anything to the front of the boards or behind without having to remove them?
I may be a bit naive here (i'm no builder).
Can the boards come off the barrier go on & the boards be nailled back on, or are they impossible to take back off without breaking?
Any solution would have to meet building reg's as I need to pass for rural renewal tax relief...

Re: Attic Condensation

The relevant building regs are available on the department of environments website http://www.environ.ie/DOEI/DOEIPol.nsf/0/a137e0322d60e09780256f5d00504a79/$FILE/30178%20BR%20Ventilation%20F.pdf

Re: Attic Condensation

Hello CMaxwell,
for starters the original p/board ceiling can't be removed to install a barrier. I would suggest he applies two coats of Gyproc drywall sealer, this will reduce vapour transmission but I'm not sure about it's effect on subsequent decoration, try contacting Irish Gypsum and see what they say. Other than than it's important that all openings for pipes etc. are sealed. The 50mm air gap is essential and this must be in place.

Re: Attic Condensation

Carpenter said:

Hello CMaxwell,
for starters the original p/board ceiling can't be removed to install a barrier. I would suggest he applies two coats of Gyproc drywall sealer, this will reduce vapour transmission but I'm not sure about it's effect on subsequent decoration, try contacting Irish Gypsum and see what they say. Other than than it's important that all openings for pipes etc. are sealed. The 50mm air gap is essential and this must be in place.

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when you say "the original p/board ceiling can't be removed to install a barrier." I assume you mean to be reused... and that they could pull it down to replace with the correct board with integrated vapour barrier (the foil backed stuff)... Would that be expensive & time consuming?

By the way thanks a million for the suggestion & I'll look into it (sealing with drywall sealer). I think what we'll do is leave it up to the builder but if he opts for an alternative solution we will keep back a grad or so from the price subject to the house passing the building regs inspection...

Anyone know how to email the building regs people directly to see if this would be accepted??

Re: Attic Condensation

In my experience emailing them is pointless, they don't answer. Phone them.
Leo

Re: Attic Condensation

NiallA said:

The relevant building regs are available on the department of environments website http://www.environ.ie/DOEI/DOEIPol.nsf/0/a137e0322d60e09780256f5d00504a79/$FILE/30178%20BR%20Ventilation%20F.pdf

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Thanks for that Niall.

"Section 2 - Condensation in Roofs
2.4 In addition to ensuring adequate ventilation, transfer of water vapour to cold roof voids should be limited as far as practicable."

It would seem that they would need to provide an outlet pipe from the extractor in the ceiling all the way to a vent in the exterior wall.
Only thing I might be caught on is that I remember the contract saying that the house was to be built in accordance with the 2000 building regs. I will check the planning docs to see if they need to comply with 2002 version.
<EDIT> Their original application went in on 22/04/2003 so it looks like they would have to comply with '02 regs..</EDIT>

Re: Attic Condensation

Cmaxwell said:

when you say "the original p/board ceiling can't be removed to install a barrier." I assume you mean to be reused... and that they could pull it down to replace with the correct board with integrated vapour barrier (the foil backed stuff)... Would that be expensive & time consuming?

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Yeah, what I meant was that the original board cannot be taken down and then reused. however taking down the board and replacing with a duplex board (foil backed) would be a big job and the builder is most unlikely to agree to this plan. It would be inpossible to get a neat corner where new board meets the existing wall finish, no scrim reinforcement would mean cracking over time.

Re: Attic Condensation

serotoninsid said:

It would seem that they would need to provide an outlet pipe from the extractor in the ceiling all the way to a vent in the exterior wall.

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I had a good check over my snag list & I'm glad I came on here last night... It looks like i have exactly the same problem as serotoninsid in that my builder has also just stuck a fan in the dormer ceiling & not vented it at all!
Plus there is already a load of condensation lying on the insulation already.

Carpenter said:

however taking down the board and replacing with a duplex board (foil backed) would be a big job and the builder is most unlikely to agree to this plan.

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Carpenter...
Yes, your right but this will leave him with 3 choices -

1. just get on with it and fix it.
2. I could pay about €3,000 less, get someone else in who is willing to fix it.
3. or walk away... (I could then sue for lost time, per performa etc.. & the estate agent would have to disclose to any other potential buyer that it isn't building reg compliant which in a section 26 area would be unsellable)

Re: Attic Condensation

Cmaxwell said:

I had a good check over my snag list & I'm glad I came on here last night... It looks like i have exactly the same problem as serotoninsid in that my builder has also just stuck a fan in the dormer ceiling & not vented it at all!
Plus there is already a load of condensation lying on the insulation already.

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Its good to catch these things now rather than later down the road - when its too late to get them sorted.

Before I go back and make them compy with this, I want to be sure that this is the right thing to do. A recent thread ('New House - Vents') is fresh in my mind - folks were suggesting that there should be as few 'holes in the wall' as possible. With thermal ratings for houses on the way in, I want to be sure I take the right option.
Q. Which would be worse - water vapour in the attic or yet another hole in the wall?