Damp

[david123]

We have a problem.
In our small bedroom upstairs we have a damp patch in the ceiling. The bedroom is in the gable of a south facing external wall within the roof area. We have had two different roofing companies around to try and find the problem. One we had used before and have been around for a long time, but we wanted a couple of quotes. Neither of the companies that we contacted could see where the problem was coming from having both inspected the roof and tiles.

The firm that we had used before could see no obvious water ingress and said that the only thing they could do was to re cement the gables, and ridge tile bedding. Unfortunately there is no way into the loft of that part of the house. They did remove tiles to look in there but could not find the problem. I got them to do the job anyway. We still have the same problem and contacted them. They reckoned the only thing that they could think of was it may be condensation, and suggested a couple of air bricks being installed. I have used a damp meter over the last week and it seems to be the same whether it has rained or not, 38%. Any advice? Would it be a good idea to dry it with a fan heater and paint it with PVA before re painting? There is no mains water or water pipes in the loft area. The dark bit above the mirror is not damp it is just a shadow.

Yours truly, stumped

 

[morfa]

Dave,

I have exactly the same problem. We're an end terrace and we have a couple of small damp patches appearing upstairs on the gable end wall. Initially it seemed like it was the chimney, so the chimney was removed. Sofits, fascias are all quite new and in good nick. Builders and roofers who removed the chimney had no idea what to do next, apart from putting new render on the whole wall. Bit steep that. So I found a company who coat walls in a water resistant paint. Got them to coat the wall with it. Slight improvement, but still not gone.

However in the loft there's now really bad condensation and (a different) set of roofers reckon ventilation bricks would be the way to go. However he's not willing to guarantee as the problem is so hard to pin down. But he thinks that's the way forward.

I do feel your pain, as I'm in the same bind. It's a real sod. Vent bricks or vent tiles are quite cheap really, so it's worth a go. Painting over it will probably stop the patches from coming back, but if you're anything like me, you know it's not fixed and you want it fixed. Dunno how much you've spent, but I've spent 3k so far, so if you've spent less than that, count yourself lucky I guess.

Good luck.

Morfa

 

[MMUK]

Dave, do you have a picture of the outside? Is this an external or internal corner of the building? Is there a valley in the roof?

 

[Mike.S]

Like MMUK says, a pic of the outside would be helpful. Do the eaves overhang the gable wall or is the roof edge directly above that wall? I'd check:

- penetrating rain: blown into gaps between edges of roof tiles, soaking wall plate then brickwork below (tends to show in plasterboard first as the gypsum wicks the moisture from the joists/plate).

- rainwater entering either at hip/ridge (and then tracking down) or between tiles near eaves/edge. Is there felt/barrier under tiles and over battens?

 

[Jacob]

Is often a buggler to diagnose but at least you can be sure its one of two things (or both): water getting in, and/or condensation.
Unless its a leak (unlikely I suppose) or relatively uncommon old deteriorated hygroscopic plaster but you get that in warm weather so I guess not.
I agree with the others above, it's most likely to be edge detailing - someone has skimped on tile and a halves, or it needs some lead flashing etc.

 

[Graham Orm]

Still looks like water ingress to me, as already said a pic from outside would be helpful. I doubt condensation would be so localised.

 

[RogerS]

You could leave the window open fora while to see if it goes...ergo condensation.

 

[blackrodd]

Do you have a chimney on that gable wall? Check out the flashings and aprons on the stack, if so.
That's a leak and not condensation. If not a chimney, The verge and barge boards need checking, It'll be coming in above, nearer to the ridge.
I suggest you bite the bullet and get access to you're roof areas. Regards Rodders

 

[david123]

You can see in the attached photo where the re-cementing of the eaves has been done. The window was put in about 12 years ago and as you can see in the photograph there are slight cracks here and there, obviously this occurred when the window was being installed. As we were concerned about it, about seven years ago we had it waterproofed. I also had the roofing contactors check the cracks out, they said they were fine but as a precautionary measure they filled them with some sort of sealant

You can probably work out for yourself by looking at the photographs where the damp patch is. All the external walls I covered internally in thermaboard when we bought the house and installed them to the manufacturers instructions but obviously this only goes up as far as the ceiling. We had this done as the building is a couple of hundred years old and is mainly solid 9 inch thick brick.

It's cost us about £500 so far and is probably going to cost us couple of hundred pounds to have the tile vents fitted. I think that is probably the next stage in the game.

Thank you for all your comments so far. And yes it is driving me nuts.

 

[Graham Orm]

Have you checked the gutter outlet to see if the downspout is blocked and overflowing onto the wall? The guttering looks ropey, but I assume the roofers would have looked at this. My guess is a cracked tile higher up the roof and the water is running down the felt and finding a hole. There looks to be a void between the roof and the ceiling. The only sure way once all else has failed, would be to make a hole in the ceiling if you have no access and run a hose on the roof while looking through the hole with a torch.

 

[david123]

Thanks grayorm.
I think you are right about that, and it had crossed my mind the other day to open up the ceiling, and may be my last option. As they did take off the roof tiles and could see no sign of the problem, I will get them to fit the vents to see if that works.
Yes I did get them to check the gutters and they are fine.
Problem is that we have put the house on the market (again) and would like the problem solved before it is sold. I don't want to pass the problem on.

 

[Graham Orm]

In that case then I think the only way is to cut open the ceiling and see where the drip is coming from. I'm pretty sure it's not condensation, that would normally form on a wall where the brickwork is cold, and also it's not likely to be so localised. Keep us informed.
Air bricks would take an age to have a noticeable effect.

 

[david123]

I rang them an hour ago and asked them to fit the vents. I can see no ventilation anywhere up there so it will need doing anyway. I will then dry the area and see what happens. After that if necessary I will open it up and have a look myself.

Thanks for all your advice, I will let you know the outcome.

 

[david123]

I decided to cut open the ceiling, as during this past few days of bad weather it has got far wetter than it would with condensation. Canceled the roofers and cut it open. What I have found is that thet ceiling plasterboard is butted directly into the original soft red brickwork and which seems to to be leaking. That is as far as I have got so far. I need to get it dried out and wait for another downpour. Photo's to follow. I will keep you posted.

 

[Graham Orm]

When you say soft red brick do you mean the inside skin?

 

[Graham Orm]

Is this an outrigger (bit jutting out from the main house with kitchen and a bedroom usually) at the back of a terraced house? If so it will probably be a 9" solid wall with no cavity.

 

[david123]

No, it seems that whoever renovated the house put up the ceiling and then plastered up to it. The edge of the plasterboard sits directly onto the face of the brick.

 

[woodfarmer]

I had damp coming through the walls of a newly built block poultry house. Even had it plastered with "waterproof render" (£450) on the outside, But still water passed through the joints and the walls were damp. Eventually sprayed the outside of the walls using a paraffin spray gun using Thompsons sealer. It cured the damp passing through the walls. Only took an hour or so and the stuff was about £20 for 5 litres. be generous with it. Cheap enough to try.

 

[Graham Orm]

No, it seems that whoever renovated the house put up the ceiling and then plastered up to it. The edge of the plasterboard sits directly onto the face of the brick.

That shouldn't cause damp. I still believe you have a leak somewhere. You need to get up with a ladder and run a hose down the roof from the ridges. Or better still start low down and work up the roof in stages, if you run it from the top, although the leak will show you won't know where it is. Whilst doing this you need someone inside looking up the inside of the roof through the hole with a good torch. I'd put money on a drip appearing.

 

[Graham Orm]

When you say on the face, do you mean sat on top of the brick wall, or just butting up to it? Photo's would help.