Ready to hire?

Post your job in minutes, browse real reviews and choose who to speak to.Post a job

Need some tips or advice?

Damp Proofing

What could be the cause of a damp strip on gable end wall?

Anonymous user 23/02/2024 - 3.07 PM

There is a band of damp appearing horizontally across almost all of the outside wall on my property, it is not one continuous strip but appears like that sometimes (it looks worse when it rains). inside the living room there are some slight damp patches appearing. The pointing was done a few years ago and appears in good shape and still intact, however the only thing I can see is that some of the internal black mortar is showing where the pointing was done this may be some crumbs mixed with mortar or maybe a poor finish. The roof appears OK apart from a few slightly shifted roof tiles nothing major looks out of place-there is no damp at the ceiling height and all old chimney breasts inside that have had fireplaces removed have vents fitted. Where would be a good place to start to try and figure out the cause of the problem? ____________--------------__________________----------_______________ Regarding the age, I'm not sure but it's a terrace that used to have the loo in the back garden, its pretty old but not Victorian/Edwardian. It also doesn't have a cavity wall, its a solid (9inch) wall. Re: damp chimney breasts-there is some damp here but it has a vent and seems drier than the alcoves which has is the worst. I've had a tradesman round who said that the gable end DPC has failed because it's below the ground floor level, I was under the impression that as long as DPC is above 150mm off the ground outside things should be fine? no part of the property is below ground. --------------------------------- Thanks Alex and everyone else, much appreciated. I wanted to ask Alex, if the damp is appearing a foot or so above the ground would it be the immediate and surrounding damp area I have re pointed with lime mortar or would all of it need doing? Regarding the DPC I was told it would need the injected cream, would this be because the original slate may have broken or given way?

Are you a tradesperson and able to answer this question?

3 Answers

ADR Property Maintenance

Rating: 5 out of 5

Boston

you don't say how old the property is or if it is cavity insulated thanks for the information, it is a solid brick house,built with lime mortar this allows the building to breathe stopping any build up of water ingress in the brickwork to escape, if it has been re-pointed with a Portland cement this stops the building breathing allowing water ingress in the brickwork to transfer from the external to the internal walls creating dampness, the worst things you can do to an old building is use modern materials on them as most modern materials are sealers rather than breathers, you damp proof course will be a slate damp proof course installed between the brickwork at floor level as long as this is above the ground level it will not be rising damp , you are suffering from penetrating damp , most likely caused by the wrong materials being used for the age of the building, go on the net and read the rising damp myth, also read everything you can about N.H.L. mortars /renders/plasters their you will find the answer to your dampness issues, your biggest issue maybe finding a tradesman able to use these correctly to solve your issues, their is no additives or cement in lime mortar/render/plaster any one who tells you different run a mile from along with anyone who wants to sell you a damp proof course. unfortunately it is still to cold at this time of the year to re point with lime mortar should you wish to know anything else just ask. rising damp is mis diagnosed in over 75% of cases rising to 95% in older properties [ thats according to latest which studies ] most damp proofing is covering up the problem with a water proof cement render/water proof sheeting ect rather than finding the source of water ingress and addressing them your slate will not have failed. without looking at the wall it is impossible to say exactly where the water may be getting in so in reality the whole wall needs to have the cement pointing removed and re pointed with a natural hydraulic lime mortar., but I have in the past pointed up just the area and surrounding areas with a fair degree of success, good luck Alex

Answered17 February 2017

LABS Building Services LTD

Rating: 5 out of 5

Sheffield

Internally is the damp appearing on the chimney breasts by any chance?

Answered16 February 2017

Anonymous user

I would take a look at the verge and check for cracks in it first. If that looks all ok then you may possibly have the rain penetrating the exterior wall, you could try a good water seal on the gable wall for this. Also dry verge capping is a good idea on older properties which will prevent the rain hitting the verge and also wind and rain driving up under the cloaking.

Answered15 February 2017