Lime pointing

[Curry]

Just looking for confirmation that its fine to render over a wall with s+c on a wall that has lime pointing.

One of the render manufacturers is saying we have to use lime render.

Any truth in this?

 

[carlos]

Sure most people will say it should be lime render to allow to breath.

I don't know for a fact to be fair.

What I do know is that there are loads of Victorian and Georgian terrace and semis around my area that are covered in s+c render. All

types smooth, pebble dash, wet dash etc that all seem to stand the test of time.

 

[malc]

we use to rake the joints out. just roll a coat of sbr on, you could put some sbr in your scratchcoat

 

[jamesthefirst]

Don't krend do a lime product, klime? Would that be an option ?

 

[owls]

yep use a lime render, we tend to use parex clair as a base coat and moyen for the colour and topping off. looks just lie there monorex gm on completion and goes through machine a treat.

 

[Render Systems]

dont use sand and cement on this as once the water gets behind it the lime bedding mortar between the bricks will hold the water and only let it breathe back into the building... use NHL 3.5 lime mortar to render or you and your customer will have problems... Conserv. Lime Mortar Suppliers & Stone Restoration Specialists

 

[yeoplast]

Lime render it, not this time of the year though, bit risky with the weather.

 

[User___removed]

Same down here.i have done it also.most buildings built back then have lime joints.

 

[stuy]

i would also go with the hydraulic 3.5 lime render with synthetic hair added but the weather is against you,

 

[PFTwales]

What would happen if you used a modern system like rendaid and a monocouche ? They say that system is breathable

 

[church]

any breathable system will work , also as carlos says s&c works

 

[User___removed]

Let's be honest,is it essential to use a breathable product in this instance?
The cost difference between s&c and a lime based render or mono is gonna be twice as much.ive done loads of s&c on stonework and if its done right no moisture should get in behind to cause problems.
All the customer wants is there property rendered so are not bothered what you use,only the cost!!

 

[church]

nailed it bobby

 

[yeoplast]

Just my 2 pence worth here, but moisture doesnt just come from the outside, it also comes from inside the house and from the ground up, the idea behind lime render is to enable this moisture to evaporate through the wall, you dont want to trap it between the s&c and the inside of the house, this will only cause problems later because the house was ment to be soft so as to enable movement through the seasons, possible cracking of the render is a sure problem for starters(its to hard for what you have described) as soon as you have one crack thats where the real problems start, the dmp gets in and its trapped, just my 2 pence worth, hope i didnt upset anyone this time.:RpS_thumbsup:

 

[carlos]

If there is moisture coming up from the ground then there is a rising damp problem that need solving first

 

[yeoplast]

If there is moisture coming up from the ground then there is a rising damp problem that need solving first

No thats where we are led to believe its a problem,old houses were designed completely different to modern houses, modern houses are biult with dpm and hard materials,(dry unhealthy houses in my opinion) old houses were biult with soft materials(breathable and to allow movement) there may have been an attempt to create a damp coures by useing things like slate for instance, however they were ultimatly designed to breath the excess moisture away or out of the walls, by useing hard materials such as s&c you only trap this moisture in the wall causing more harm than good, for instance imagine you have a house biult of cob(mud, aggregate and a binder) would you say it was ok to render it in s&c trapping all moisture inside the wall to eventually rot away the very stucture you are trying to protect? hope this all makes sense.:RpS_thumbsup:

 

[Rigsby]

I understand how lime render makes walls breath so any moisture on the inside can breathe out. But on the other hand a lime rendered wall is very absorbent so when it is winter and the air is damp these walls can absorb this damp inwards and through to the inside causing no end of health problems? But then when the air dries up the moisture is taken out of the walls into the outside air and if we haven't died of pneumonia or bronchitis by then life is a good un.

Going back to how how the old houses was built? drafty sash windows and open fireplaces in every room. whether we liked it or not we had ventilation coming in and out which helped with the sodding damp lime rendered and plastered walls. But that was last century and the one before that. Now we have eliminated those draughts in these old houses. Bricked up the fireplaces (exit) and fitted draught proof windows and doors (inlet). So we have sealed up the house. What air is in stays in. And that horrible cold damp outside stays outside.

Hmmm........Those pesty solid wall lime walls are letting damp in. I know! stop the the damp! we stopped the draughts so lets seal that sodding absorbent walls, lets re render with a waterproof render what is supposed to be breathable as well so they say.

So there we have it! No draughts, central heating that keeps in and dry walls. Err no not exactly, the damp is still there! Showers, baths, cooking, drying clothes on the radiators, sweating all creates moisture in the air. It then finds a cold spot like a cold solid wall and condenses. Damp!

I look at quite a few houses where the customer asks about breathability and wants to know how much for lime render so the walls can breathe. But then on the inside no ventilation what so ever. Walls have been uni-bonded and skimmed so the inside of the walls are well and truly sealed with a plastic film. All the mod cons but they want the walls to breathe? Whats the point! All the other old house measures are missing. Dumb arses!

But I have lost many a lime job by telling the customer all this but now I think to hell with them. Hippy sorts anyway, flower power and all that. So long as I get money for it I will give them what they want not that it will work.

So I have a 1912 terrace on rent that I am well and truly going to fully seal up airtight if I can and have insulated render on the Northern side and iwi on the front South side to preserve the brickwork so not to have a Vera Duckworth style house if you know what I mean. As for condensation I am going to have a Envirovent fitted and maybe if envirovent approve a moisture detectable automatic extractor fan in the kitchen and bathroom. So a converted old house to new build spec on the insulation side but ventilation built in.

My only concern is the iwi? 9" solid walls with little heat loss. These walls absorb moisture but heat loss dries them out as well. lose the heat loss and the walls are going to suffer from frost damage more easily. I will be applying something like dry zone to keep the walls dry but it is a theory of mine as the chimney stacks have not had heat loss for at least 20 years and they need rebuilding as most of the bricks are frost damaged and porous.

 

[User___removed]

I say to the customer the best solution is a lime based render for ##m2 although if you want a S&c product it's ##m2.
Explain which system is best suited for the property then leave it up to them to make the decision.9 times out of ten they will choose S&c because it's the cheapest option.


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[yeoplast]

I say to the customer the best solution is a lime based render for ##m2 although if you want a S&c product it's ##m2.
Explain which system is best suited for the property then leave it up to them to make the decision.9 times out of ten they will choose S&c because it's the cheapest option.


I'm using The Plasterers Forum Mobile App

Yep not many people these days want the most expensive option, but that does depend on the clientèle, as rigsby says there are alot of terreced victorian houses that have already had the damage done by mostly preservation companies and the like imo, new technology like trickle vents in windows aid with ventalation, old fire places shouldnt be blocked up without ventalation, but i have seen plenty of places done like this, things like dpc injecting are only expected to last what 20 years! what then? start again! is this ok? Alot of damage can be done in that period of time, i guess im just a purest and like to try and put back what was there in the first place or at least try and use compatable materials, i dont know, if i do the right thing it makes me feel good about what i have done for the property, somebody has to try and save them otherwise they will all be gone oneday, think im just babbling on about it now, at the end of the day people will do what ever they want to and thats it.