One for the building gurus - cavity/loft insulation woes

[TamSV]

Mrs T took advantage of a local authority supported deal for funded cavity wall and loft insulation. Got it done in January this year.

On my annual trip to the loft to fetch the Christmas tree it was smelling very musty and the cardboard box with the deccies in felt a bit soft.

Got some decent light up there and it's bloody soaking. The rafters are damp to the touch and the roof boards are properly dripping wet to the extent that a lot of them are now warped and bowing in to the loft. This is on the side of the roof that gets most of the wind/weather. Don't know what the boards are made of - they're like plasterboard (probably bloody asbestos).

In the interests of the full disclosure required for technical advice threads ;), this is an early 70's semi-detached George Wimpey house, 2 storey, brick, tiled roof. The cavity wall insulation is little silver polystyrene balls whose main aim in life is to find their way out of the brick vents. The loft insulation is the usual stuff but about 8 inches deep. The loft is unfloored. Heating/water is on a high pressure system so there's no tanks or water pipes in the loft.

The soffits were replaced with uPVC but this was done years ago before I bought the house so isn't connected. There's no vents in the soffits but next doors still got the timber up there and I can't see any external vents in his either.

Any particular thoughts?

[Owenski]

Whats the Roof construction?
You got 150x50 joists at 400mm centres then 2x4 forming the pitch of the roof with further horizontal battons to which the tiles are nailed?

Or is it a modern truss roof with smaller joists and lots of internal angles timber for rigidity? Same battons horizontally for the tiles.

Is the moisture localised or is it all over throughout?

Condensation can cause an issue but this would be a very extreme case of it.
Other than that it could be a leak, which ever of those two though the solutions are both relatively simple.

FYI GET A DEHUMIDIFIER UP THERE ASAP.

[BigBaddad]

How is your loft space ventilated? Many roofs have vents in the eaves. The guys that fitted your insulation might have blocked them. I can guess that the guys fitting it are subcontractors on a price per job. Does the insulation meet the pitch? It might just be a case of pulling back and cutting back the lagging to clear your vents. If not then you will need to add it some vents somewhere, at the eaves, on opposing gable ends or on the pitch.

[Specialone]

My guess, the muppet insulation installers have blocked airflow off and it's condensation.

You haven't got a bathroom fan going into the loft have you? I've seen it where they have knocked this pipe off the vent and the customer didn't know, caused tons of condensation.

Where the roof meets the loft floor, the eaves, there should be a bit of a gap, the insulation should not block the eaves off.

[johnnyrod]

Deffo sort out some ventilation, it should have some anyway (prob now blocked as said) but if not then it's airbricks in gable ends, soffit vents, or maybe replacing some tiles with ones with ventilation stubs on them. I'd also look for signs of rain getting in, as said this would be a lot of condensation, so look for streaks etc. where lots of water has been coming in. Don't delay!

[MisterTommyH]

Just as an aside - if you've paid / had a grant to have this insulation installed to modern standards then the insullation should be both between the joists and then prependicular over the top of the joists so you can't really get boards down.

I agree with SP1 it's probably a condensation problem.

[BigBaddad]

Further to my previous post, because of the insulation your loft space will be much colder now, and will condensate more.

[Roberrrrt]

+1 sounds like blocked vents

[TamSV]

Thanks folks. I was thinking lack of ventilation as the moisture is basically everywhere.

There's no bathroom extraction fan but there's three recessed lights from the bathroom which are probably letting a bit of moisture in, but not to cause the extent of the problem I seem to have.

I only had a quick check last night so I'll get up there again later on for a proper mooch about.

[maviczap]

I had similar issues, although not as bad as yours. I'd fitted some of that foil insulation to my rafters, but I only got one side done.
During the winter months there was condensation on the outside face of this insulation, which was dripping down here and there, in small patches.

Although the fibreglass insulation in between the joists is pulled back from the barge boards/soffits, there aren't any vents in these.

Some of the moist air is coming from the bathroom recessed lights, so I'm going to install some vents & a fan to duct this away.

When I get the soffits or barge boards replaced, I'll have ones with plenty of vents, as the ones on my house are just planks of wood with the guttering attached.

Its all down to a lack of ventilation in the space

Oh, I've taken down this insulation until its sorted

[andrewsmith]

How is your loft space ventilated? Many roofs have vents in the eaves. The guys that fitted your insulation might have blocked them. I can guess that the guys fitting it are subcontractors on a price per job. Does the insulation meet the pitch? It might just be a case of pulling back and cutting back the lagging to clear your vents. If not then you will need to add it some vents somewhere, at the eaves, on opposing gable ends or on the pitch.

This!
Get up there and have a rip about. Yours is a 60's council ain't it?

[TamSV]

Here's the damage. This is all across the North side of the roof. The South facing pitch is nice and dry.

http://i918.photobucket.com/albums/ad23/tomSV/25832022-7A1A-4D91-ABD9-28764D459A3C-16116-000018D9740A7536.jpg

On the dry side - a nice gap in the insulation.

http://i918.photobucket.com/albums/ad23/tomSV/3A693F56-3A74-4476-9775-D47B407AFCE8-16116-000018D96390C594.jpg

And on the wet side - there's a gap in the new insulation but there's a load of the old stuff bunched right into the eaves.

http://i918.photobucket.com/albums/ad23/tomSV/CFC77AE0-562B-483F-A1A4-A7D5C2A86440-16116-000018D9802B5F0D.jpg

I'll clear all that out for a start and see how we get on once I've got it all dried out.

[Teejayexc]

If I was you I'd be on the phone to the local authority you contacted in the first place. They should either, get the muppets to come back and do the job properly, or re-imburse you for having to hire someone to sort the bliddy mess.

[Owenski]

Am I seeing that right, is your roof ply lined from the outside of the truss?

The other side of that ply wood do your tiles just nail straight through the horizontal battons they mount on?

If that cavity isn't properly vented that's blatant incompetence, I'm not one for blame coulter but Im damn sure as hell not one for paying for other people's mistakes either! Get onto those who did the work, that's a proper **** up IMO

[tigersaw]

I thought they were stalactites, now I see they are nails

[TamSV]

Am I seeing that right, is your roof ply lined from the outside of the truss?

The other side of that ply wood do your tiles just nail straight through the horizontal battons they mount on?

It's plasterboard on the trusses not ply.

What might look like wood grain on the pics is actually wrinkling of the paper on the outside of the plasterboard caused by the damp. I assume there's then timber batons on the outside of that which the tiles are fixed to.

[Specialone]

Plasterboard, wtf? :confused:

[Owenski]

Plasterboard, wtf? :confused:

+1,000,000

a world of Dafuq¬?

[Wideboy]

Das ich wtf??

Chances are its some sort of asbestos insulation board rather than plasterboard as its been used up to the 90's, but still wtf it should be on the inside. I've only worked on a few roofs and conversions but I've never seen anything other than felt on the outside of the trusses.

[widepants]

Too true Gav