druddle

I have just moved into a 5 yr old house. In the loft it really smells damp, and all of the underside of the roof seems to have moisture on it, that drips down onto the loft lagging.

Is it normal to have alot of moisture on the inside of the roof ? I havent seen in the house i lived in previously (15 yrs old), and it means that i dont want to store anything up there.

If it is a normal thing, is there a way i can make it a bit drier up there ??

Forgot to mention that this house has full gas/radiator central heating and the previous house has gas/warm air central heating.

dave

[Edited by druddle - 12/17/2001 8:26:32 AM]

DominicA

doesn't sound good to me....

chiark

NOTE THAT I KNOW NOTHING ABOUT ROOFING. IGNORE ME. I AM AN IDIOT. Right, with that out the way...

Depends on how the roof is constructed as to whether this is "right" or not, but I have to say that it doesn't sound sensible, or right, by any definition of the word.

If the house is only 5 years old, you should have a warranty from the builders as I think, though could be wrong, that they have to provide a 10 year warranty of sorts. I'd get them to come around, and start from the position that there's something wrong and let them try to tell you otherwise. As always, don't get shirty with them, but do make your point well and don't accept flannel.

AIUI, you can overlap the tiles so much that the chance of water ingress is reduced, or you can tile and use a waterproof liner. It sounds to me that your tiles aren't overlapped enough as you don't have a waterproof liner. Or perhaps that's torn.

If they end up replacing the tiles, make sure that the tiles used aren't too heavy for the roof construction as this WILL cause you problems if you sell the house...
...it did for the people that bought our house.

Good luck with this one. The original builders would be my first port of call. If they say "it's normal", get an independent roofing contractor to quote for repair, then wave that under the builders' noses.

Nick.

druddle

Just spoke to NHBC and they say that because its on the entire inner surface of the roof, then it must be condensation, which is a reasonable assumption to make i suppose.

He said to check if there are any roof vents that are blocked, and maybe that there are not enough vents to start with. If this is the case, then some more need to be put in.

Then to help keep the moisture away, whack a dehumidifier up there.

Is this a reasonable thing to do ??

Dave

Brendan Hughes

Is there a gap under the eaves, or has it been blocked by rockwool insulation? When I added insulation to mine the instructions clearly stated not to block the gap at the ends of the runs with the felt, but to cut it a bit short to leave an air gap to vent the roof. Surveyor also noted that the gap had been left, in his report. Not sure what the symptoms of non-venting would be, if it would cause such moisture/condensation, but it's a suggestion.

BJH

Dave T-S

The building regs on a five year old house would have been stringent - modern rooves are designed to have ventilation/air flowing through them. There should be ridge vents, and vents under the eaves. As Brendan says, most likely the roof insulation has been jammed under the eaves blocking the vents .

Roof insulation is the job builders hate to do, and it's invariably done badly (it has been in the four new houses i've had.....)

druddle

I will get up there this week and have a look. If the Rockwool is jammed up against the end, then i will get the stanley knife out and cut it off so that air can get through.

Cheer guys, Scoobynet is great, you can ask the most obscure questions and someone always know the answer !!

Dave

chiark

Ventilation! (Slaps head) Of course! Everything has to be built this way, including an extension on my parents house that required a new bit of roof. D'oh!

So it's condensation and not a leak, which is nice to know. Hope you get it sorted.

ozzy

Druddle,

I'm no builder, but I'm having the same problem with our house at the moment. If it's over the entire roof, then it almost certainly a condensation problem.

We've just had the roof checked and the builder couldn't find any cracks/holes to suggest a problem with leaks. We noticed some patches appearing in the corners of the rooms. First I thought a leak, but then I notice the whole roof was moist.

The Builder's hopefully coming back this side of Xmas to look at the air-flow in the roof. We had some work done a while back (storm damage repairs) and it's look like those muppets haven't left the roof venting properly.

As Dave says, check the ridges and eaves as there should be plenty of ventilation. There's some calculation based on the volume/area of the roof to work out just how many vents you'd need.

From what I've been told it's almost inevitably poor ventilation causing the roof space not too breath properly. All that hot moist air just hangs around waiting to start condensing on the inside of the roof.

Let us know how you get on.

Stefan

Toerag

If the house has 'plastic' windows expect to get condensation everywhere. My parents house (26yrs old) never suffered until they put the plastic windows in.

fast bloke

Druddle - I think your answer lies in the advice above, probably too much rockwool. The stuff in horrible to work with. It causes terrible skin irritation, and if you put enough protective clothing on you can move about a tight loft, so you would probably be better to get the builder to fix it under warrenty if you can.

Toerag - a 26 year old house probably won't have the same ventilation as a new house. Your parents would probably be best to gets the soffits replaced with ventilated ones. This is a 2 hour job and shouldn't cost more than a couple of hundred quid for PVC ones. Untreated condensation can cause major problems (warping timbers - warping roof - leaking) so it is best to spend a few quid sorting it now

Kempo

Noticed the same problem this weekend - the reason being outside was chuffing cold, inside nice and toasty but I had the loft hatch open for a couple of hours while sorting out Xmas decs! When I first went up it was ok, an hour later there was condensation dripping everywhere.

I also think the side vent might be covered with some of the lagging so will have to check that. I'm not too worried about the problem as it must have been the sudden temperature gradient between near zero roof lining and 20 degree heat coming up through the hatch.

Will make sure I don't have the hatch open too long next time!

Paul

mattstant

Druddle any probs with nhbc or builder email me
i am a builder and this is a constant problem with new buildings as all moisture in buildings now nearly always ends up in the loft.
Have you got mechanical vents in the bathroom /kitchen these are now requred by building regs as are permanent vents in the heads of all windows.
the problem lies with the increased efficiency of insulation in buildings and with double glazing means that there are no cold surfaces to condensate moisture so now the coldest part of the structure is the roof space.
moisture in warm air will pass through to the loft and become trapped without proper ventilation and this ventilation needs to be "cross ventilation" ie allowing a flow of air from one side of the roof to another the roof shape can be critical in calculating this your local building inspector may be more use than the nhbc (dont let me get started on them).
Most of the posts are right in saying that your problem could be insulation blocking vents as usually the most ignorant grunt on site gets the ****ty job of insulating the loft


edited to say Chiark your first assumption was correct <img src="http://www.data-techniques.net/cwm/otn/realhappy/biglaugh.gif">

edited to try and get smiley working
[Edited by mattstant - 12/17/2001 12:25:16 PM]

[Edited by mattstant - 12/17/2001 12:50:09 PM]

druddle

mattstant

I am going to look at the loft insulation, hopefully that will show me the source of the problem.

I was told not to put a dehumidifier up there, as it will only suck in air from outside once i have cleared any vents.

As for extractor fans, i have 2 in each bathroom. i will check if they are vented to the roof or a soffit, but it wouldnt surprise me if they are just "extracting" into the loft space - instant condensation !!

edited to say that all windows have vents in the top.

Thanks for your help !!

dave

[Edited by druddle - 12/17/2001 12:35:46 PM]

mattstant

first i get flood control telling me i have posted twicewhich i havent then two post turn up ????
Go figure

[Edited by mattstant - 12/17/2001 12:44:03 PM]

mattstant

ok druddle
goes to show about nhbc definitley not a good idea to put dehuimidifier in loft as it would only be a short term solution
sometimes previous owners block up vents thinking the gale blowing through there loft is losing them heat!!!! thats what 6 inch of insulation is for.

cheers
Matt

druddle

nipped home at lunch and had a look in the loft. lo and behold all the 6" loft lagging was butted up against the corner, covering all the vents. i pulled it back to uncover the vents on a bout helf of the loft that i could easily reach both sides and within about a minute i could feel a draught up there.

also the 2 extractor fans are vented to ducts in the roof, or at least they would be if the loosely taped ducting was stuck on the vents. will do that tonight aswell as moving the rest of the lagging.

hopefully should sort this out.

thanks ever so much lads, this has been really helpful.

dave

John Catlin

Dave,

Have you just purchased the house ?
and did you have a survey carried out /

If the answer is yes to the above sue the buggers.

All the best,

John Catlin

druddle

Just checked the loft after clearing half the vents at lunch and boy what a difference. Much colder but much less moisture and damp smell.

Dave

HHxx

Druddle,
I think the current regulations state this should be 8in thick, but there is talk of raising this to 10in soon.

H
- Just some useless info prob.