Patches of Damp

[mor_cf]

Hi I have a room on the 2nd floor facing southwest with a pebble dash wall..

2 years ago we had patches of damp appearing mainly by the windows area and adjoining wall next door (inside) the paint was discoloured bubbled and peeled off and had black patches under the peeled off paint.

We got a few people to view and they said the external render/ pebbledash seemed ok (by looking) and they advised that it is coming from the chimney area as there was a crack hole with the brick exposed. So we got that filled in and there was a old blocked Air vent which we installed a new Anti Draught Air vent (Core drill with baffle). And got the effected wall section by the windows (entire wall) plaster re skimmed (Skimming over old plaster). We even had the external pebble dash wall painted to cover any hair line cracks.

After 1 years we did not paint the wall yet but started to see the damp parches appearing again in the same places.

Got some more people to look at the problem again. and they said it might be the roofing. Got a roofer who came in and looked at the roof he inspected the roof externally the tile and lead flashing and capped off chimney and said every thing was good and looking in the loft and said the chimney has been removed and end's in the loft, and the felt was good. Then he got a damp meter and tested ABOVE the internal areas where the damp was and said its 100% not the roofing as it too would be damp.


Then we got Another Damp specialist who came in and did the usual with the damp meter and this time hitting the external pebble dash said there was patches of blown off pebble dash as it sounded hollow.

But what confuses us is that certain areas of the external wall seems solid and why would the adjoining wall next door to my neighbours house too be effected in a small section? and would small patches of blown render just by the windows area cause such damage?

Photos added before skimmed plastering, and Inside loft of Chimney Brest that is removed

 

[KenGMac]

mor_cf, good evening.

Is there Cavity fill in the external wall???

Ken

 

[mor_cf]

Hi Ken thanks for the reply

This property was constructed around 1910 and people who came out said there was no cavity wall.

 

[mor_cf]

Just to add also this is what the property look like from the outside. White pebble dash render. I manage to get on the Flat roof to inspect and could not see any large cracks. the wall has been painted. But just around the windows frame it sounded hollow when I tap it. but as the internal images show it is around the windows and away from it in sections. but the render towards the left of the windows sounds ok. hope this helps

 

[vinn]

Its probable that the render was originally applied because there were
problems of damp penetrating the solid wall & appearing on the interior wall surfaces.
The only suitable paint for render is masonry paint - if you have whats called "plastic" paint then it will make things worse. Moisture will be retained in the wall.
If the render sounds hollow then its blown and will have to be renewed.

When the bed room chimney breast was removed its possible that the sooty brickwork was not wire brushed and blinded with SBR for example. A sand and lime render mix should then have been applied not a gypsum plaster.
The patching and skimming carried out by yourselves is useless it wont prevent damp or condensation.
Hacking off the plaster on the external wall, including window reveals(?) and back say 1m on the return wall for the full wall heights, and then treating as above would be the way to go.

How is the remainder of the chimney breast supported in the loft?
Are there any damp signs on the extension knock-through lintel area below?

 

[KenGMac]

mor_cf, Hi again

Following on from the above post by Vinn.

if your external wall is a so called "solid brick- One brick thick" as opposed to a "Cavity Brick" wall then that may give a clue to what is going on here??

A so called solid brick [One brick thick] wall is an arrangement where there are two courses of Brick, built side by side, but no cavity.

The so called "Cavity wall" does exactly what is states, that is there is an Air Gap of generally 50.mm. between the inner and outer leaves of the brick, hence My original Question? [about Cavity Fill?]

To recognise a "One Brick Thick" wall the bricks will measure about 230.mm.
The external roughcast render might be about 15.mm
The internal plaster will be "About" 20.mm
Please note all above dimensions are very, VERY approximate?
In total about 265.mm.??

A "Cavity Wall" might be somewhere in the region of---
External roughcast render + Internal Plaster as above [35.mm]
But the brick should be[with a 50.mm Cavity] 280.mm
In total about 315.mm

Can you please measure the thickness of the wall and give us a clue as to what may be happening here?

As vinn has stated, if the external roughcast render has failed, the surface is sounding "Loose" and Boss then the Roughcast render should be considered at present having failed??

One thing at a time? can you please get the dimensions of the wall??

Ken.

 

[mor_cf]

Vinn and Ken thanks for the reply

I am not a builder, got a plaster to come and do the internal skimming on his advice. We had thought the leak had stopped when the cracked chimney Externally was fixed.

That was 2 years ago. and 1 year after leaving for a while got the wall re skimmed and Air Vent Fitted.

I can confirm we don't have a cavity wall when we installed the Anti Draught Air Ventilator Core Drill Hooded Cowl Wall Cavity vent Aero which measures 5 inch 127mm x 358mm had to be cut down by the installers so ours is a One Brick Thick" wall the bricks will measure about 240 mm

House was actually newly paint around 2 months ago and can confirm with masonry paint. (sandex)

Going to the information about re-plastering "Hacking off the plaster on the external wall, including window reveals(?) and back say 1m on the return wall for the full wall heights, and then treating as above would be the way to go."

If water was coming from the rending outside if it blown would this solve the problem or could water still come in causing damage to external wall outside or would it be advisable to repair blown render as well?

Wall adjoining with neighbours is very strange as we do have a damp meter and reading are very high 1/2 meter from skirting board for a section of around 30cm around then it goes to the medium range and then becomes higher again towards the middle of the wall so around 2 meters up and then go into the medium to low range as it gets higher again. Have also check corner wall which meets the rear wall and these seem to be lower reading again

Have taken a few photo of what is left of the chimney from the loft area and have added these here.

Any further help of advice would be great.

Thanks

 

[vinn]

I can see a lintel supporting the remaining c/breast - what material is the lintel: wood, steel?
How have you managed to take the photos showing up the flue?

If the render is loose then it must come off - typically, its the best practice to remove all the render rather than try and patch.
Remove all the affected, internal wall plaster from the outside wall & the party wall - then render as above. Only SBR the sooty area.
This way you at least take care of two variables.

Your verge has not been bedded on an undercloak.
Rendered chimney stacks are a constant source of trouble - plus I dont see any flaunching or chimney pots? Is the stack lead flashed?
Only a possibility but moisture could be entering your property from your neighbour's side of the stack or the roof?
What do you mean by "the chimney cracked"?
What is photo 216.6 showing?

 

[mor_cf]

Hi,
Not to sure about the Lintel but do believe it maybe wood as did not see any steel in this area.

As for taking the photo, The Chip board that you see in front of the remain stack (photo 1801) this can be pulled forward and you can just about fit phone under to take photo, either side. (Photo 1755 & 1750 are how it looks when board is pulled out) Though the chimney is rectangle when looking it looks like it maybe 2 separate flue's is this normally.

Can i just ask do you feel that this could be 2 problem Rear of house being caused by Blown Render in places and Wall adjoining neighbours to do more with the Chimney area?

Can i just confirm when you say the Verge is not bedded (what does this mean?)

The Chimney stack have been totally capped off so no chimney pot or flaunching. It does have lead flash around base of chimney stack have had a few roofers in and all have said this look okay. 2 Years ago when problem first started before we had chimney fixed it was cracked as shown in picture attached.

Photo 216.6 is under chimney at the base

Now have been in loft area when it rains and have never seen any water running down from wall or felt and felt looks to be in good order to. However when it does rain walls are definitely becoming more wetter on both sides. Now today it did pour down. and took damp meter reading before and after. In most area it seem to jump between 3-5 % higher after rain. All wet looking patches seen in 0855 photo below are reading between 20 - 29% where as most other area are between 12-18% We also placed outside as well and wet patches are similar measurement outside as well and what seems to look like the dry patches are much lower.

I hope this can possible be of some help as we have had so many different people in, but seems to mystifier everyone.

Thanks

 

[vinn]

Your wood lintel & chipboard support are totally inadequate for purpose but the c/breast must be well tied in to keep hanging there - anyhow, now you know.
The skim of mortar on the stack is fragile, and no venting can be seen.
The stack render is failing and will allow moisture in.
The stack flashing cant be seen either, so i cant comment on it.

I can only repeat what i suggested above - forget about solving mysteries with a "damp meter" and simply hack off and render. If possible, work with your neighbour but keep it simple.

No picture showing the crack is appearing in your post?

Why not google for any terms you dont understand?

 

[mor_cf]

Vinn Thanks for the quick reply.

The chimney i meant chipped see picture 97.9 the front edges. Ok my question with the chimney is that it is totally sealed from the top as seen in picture 113.6. yes there are no vents. some people who came out said that it is not necessary to put vents and my neighbours chimney is the same design.

My question if there is a problem in the chimney would it possibly effect the external wall by the windows area as shown in pictures i have supplied. as like i said before the external pebble dash render has no visible cracks and been painted. but i can hear hollow sound only in certain small patches and most around window (but not all of window) and not in the middle of wall . would this cause so much damage to the was as shown in the picture?

I am sure you will understand most of my work to eliminate the problem no other person who came out told me. like i said they first said from the chipped edges of the outer chimney stack to the condensation and needing ventilation. then they said the roof got many roofers who inspected the led flashing on the bottom surrounding the chimney and under to see if the tiles are ok, and they looked at the top of chimney and said it is solid.

In 2 years since we first notice this we have had Roofer's, Chimney Experts, Damp People & Builders.

So before i spend money to get some work completed i would like to know i am on the right track to solve the problem.