Bit of old school advice pls ..

[andyR]

Need to pick the collective wisdom....
Ive picked up a job renovating a victorian semi, the walls still have the original liime plaster, I can clearly see the hair and chopped straw render, non haired float and the lime putty set. However, some idiot in the 60's decided to put a cementitious spar dash render on the exterior. This has caused a few internal damp problems as the building cant breathe properly now.
That aside ive had to strip off some of the damaged plaster inside and need to replace. The place is built with very porous buff and red common brick, some of which has spalled. I did speak to BG, who despite my misgivings recommend i use their dri-coat followed by renovating plaster skim.
What id like to know is.. whats the opinion of using, say NHL 3.5 1:2 with washed sharp sand, and chucking in some hair for the render coat, floating with the same minus the hair, then just set with a renovating plaster? Do these renovating plasters still allow the building to breathe as well as the tradtional lime?, or am i gonna have to revert to lime? im keen not to intensify any damp problems by sealing moisture in and concentrating it where it can get out.

 

[flynnyman]

So what your saying is someone rendered it in the 60s and its took 50 years for someone to say "you know what im getting sick of that damp lets get it sorted"? Why do you think the render has caused the damp?

 

[andyR]

Someone did notice the damp before, they stripped the plaster off n filled the big deviations with a mixture of things, polyfilla, concrete, oh and a coppy of the daily express from july 1980 in one place, with a little polyfilla over the top of course. Seriously though, there was an old dear living in the place for forty/fifty years on her own. She croaked it at the end of last year and its stood empty since then. I think the render isnt helping the damp because its cement based and its a 1920 solid wall house, cant see the render allowing the walls to breathe as well as they might.... could be wrong. Theres no other reason i can find, or the guy i use to treat damp. Theres no point in having a dpc installed either due to the external render. These old places were designed to breathe internally and externally and find their own moisture balance via evaporation, as opposed to the modern way of excluding as much moisture as possible with modern methods.

 

[flynnyman]

Someone did notice the damp before, they stripped the plaster off n filled the big deviations with a mixture of things, polyfilla, concrete, oh and a coppy of the daily express from july 1980 in one place, with a little polyfilla over the top of course. Seriously though, there was an old dear living in the place for forty/fifty years on her own. She croaked it at the end of last year and its stood empty since then. I think the render isnt helping the damp because its cement based and its a 1920 solid wall house, cant see the render allowing the walls to breathe as well as they might.... could be wrong. Theres no other reason i can find, or the guy i use to treat damp. Theres no point in having a dpc installed either due to the external render. These old places were designed to breathe internally and externally and find their own moisture balance via evaporation, as opposed to the modern way of excluding as much moisture as possible with modern methods.

I doubt its the rendering i would say whatever its been patched with is holding the damp from condensation hack out the patches and use a sutable product then see what happens rather than take the render off.

 

[andyR]

um.. i wasnt gonna take the render off, just need to repair the internals and redo a room where im knocking through inside. just re-read what i wrote. Didnt make it clear im working inside the property did i. my bad. I'm seeking advice as to wether my solution for the inside is workable.

 

[flynnyman]

um.. i wasnt gonna take the render off, just need to repair the internals and redo a room where im knocking through inside. just re-read what i wrote. Didnt make it clear im working inside the property did i. my bad. I'm seeking advice as to wether my solution for the inside is workable.

OH i thought you said the external render is causing a damp problem. Just give the wall a lick of a suitable acid to stop efflorescence coming back then a sand and cement with a waterproofer and skim.

 

[andyR]

yh, sorry, i wasnt clear. S&C with waterproofer will let the walls breathe enough u reckon? im gonna leave em to dry out for a couple of weeks while i do the rest of the place before i hit those walls.

 

[flynnyman]

It wont hold the condensation which i think is the problem

 

[andyR]

fair one, cheers mate

 

[lucius]

yh, sorry, i wasnt clear. S&C with waterproofer will let the walls breathe enough u reckon? im gonna leave em to dry out for a couple of weeks while i do the rest of the place before i hit those walls.

Ffs get a life S&C with waterproofer will let nothing breathe, dont listen to Flinney he is talking Dick for some reason nothing will work properly untill you resolve the issues on the outside render.

 

[flynnyman]

Ffs get a life S&C with waterproofer will let nothing breathe, dont listen to Flinney he is talking Dick for some reason nothing will work properly untill you resolve the issues on the outside render.

OH so your diagnosing the external render that was done in the 60s as the problem,why? dont bullshit me about the walls breathin, i bet a lot of things have been changed in the house since then that are more likely to cause the problem. xx

 

[mark ross]

No boby can diagnose the issues here until properly surveyed in person..???

 

[bubbles65]

Ventilation

 

[lucius]

OH so your diagnosing the external render that was done in the 60s as the problem,why? dont bullshit me about the walls breathin, i bet a lot of things have been changed in the house since then that are more likely to cause the problem. xx

Merry Xmas Flinny xx

 

[flynnyman]

Merry Xmas Flinny xx

And a Merry Christmas to you xxxxxxx

 

[lucius]

OH so your diagnosing the external render that was done in the 60s as the problem,why? dont bullshit me about the walls breathin, i bet a lot of things have been changed in the house since then that are more likely to cause the problem. xx

Quite agree mate the changes have probably aggravated the problem, what ime saying is that the outside SC render is stopping the brickwork from breathing and releasing moisture created by modern living associated with cooking, washing people living in the house and has been said lack of ventilation.

 

[IanLime]

To AndyR,

Not wishing to start WW3 but you were probably right the first time. Impossible to be certain without taking a look at it though. I do mostly lime work these days and if you want to do it in lime 2.5:1 sharp sand to lime NHL3.5 or NHL2 for the scratch & float coats is fine with synthetic hair (or screeding fibres, same thing). I hair both coats to keep cracking to a minimum then use a premixed lime finish (which is very fine sand & lime putty), saves mixing it up yourself which is a pain with putty & silver sand. There is a lot more to it than that but from your post I think you've a pretty good idea already. If you want to talk about it, email me & I'll give you a call. There are other alternative methods using fat lime backing coats but these take 3 weeks to set so may not be practical. If the building is listed you may have to use horse or other animal hair, all of which are pretty easy to get hold of. Most of the renovating plasters commercially available like Limelite are actually cement based so I'd give them a wide berth unless they are specified. Hope this helps.

 

[andyR]

thanks for the help guys... still unsure what im gonna do, though im coming down more on the side of lime as i dont wanna have to go back and redo it should it be a problem.

 

[henry]

We hear this a lot walls need to breathe hmm breathe what.
Anyway dont listen to flynnyman , he does not take onboard there is such a thing as rising damp LOL.

 

[flynnyman]

We hear this a lot walls need to breathe hmm breathe what.
Anyway dont listen to flynnyman , he does not take onboard there is such a thing as rising damp LOL.

Not to 3 foot lol

 

[alf]

yh, sorry, i wasnt clear. S&C with waterproofer will let the walls breathe enough u reckon? im gonna leave em to dry out for a couple of weeks while i do the rest of the place before i hit those walls.

No it will be no good on the brick. It all should come off and be redone in lime, inside and out if you want to solve the problem. NHL needs no hair in it...

 

[alf]

To AndyR,

Not wishing to start WW3 but you were probably right the first time. Impossible to be certain without taking a look at it though. I do mostly lime work these days and if you want to do it in lime 2.5:1 sharp sand to lime NHL3.5 or NHL2 for the scratch & float coats is fine with synthetic hair (or screeding fibres, same thing). I hair both coats to keep cracking to a minimum then use a premixed lime finish (which is very fine sand & lime putty), saves mixing it up yourself which is a pain with putty & silver sand. There is a lot more to it than that but from your post I think you've a pretty good idea already. If you want to talk about it, email me & I'll give you a call. There are other alternative methods using fat lime backing coats but these take 3 weeks to set so may not be practical. If the building is listed you may have to use horse or other animal hair, all of which are pretty easy to get hold of. Most of the renovating plasters commercially available like Limelite are actually cement based so I'd give them a wide berth unless they are specified. Hope this helps.

I wouldn't go for NHL 2 for a scratch coat, it's weaker than 3.5 for a start... You have no need to add hair with NHL limes....

If it's grade 2 listed you will get away with NHL lime but if it's 2 star or 1 you will have to go for a lime putty with hair in, like for like. EH are not bothered too much about grade 2 buildings.