Advice Request

[David]

I have recently purchased an old property in the conservation area of Balderton, on the outskirts of Newark on Trent.

Unfortunately at some point in the past the property has been rendered using a cement based render instead of lime. The situation has been made worse by the application of 'plastic' paint. The render on the front of the house is blowing out and the paint is peeling off in several places, the badly effected areas are all under the front windows.

To the rear of the property the house hasn't been rendered but has been painted with 'plastic' paint similar to the front. Similar issues are resulting from this.

What would your recommendation be? Could I get away with repairing the front wall from below the level of the windows? Does all the cement render need removing? We have only just purchased the property so are on a limited budget at the moment, but would like to do something to improve matters prior to the winter months. Any advice for removing the paint from the back of the house?

Any advice you could offer would be appreciated . Lastly, does anyone know of any tradesmen in the Newark area that might be able to apply lime render when the wall is ready?

Many thanks

David

 

[malcolm]

The painted bricks at the back are easy. Worth a search on here. Any sort of blasting will damage the face of the bricks. You need paint stripper. I tried a lot of strippers then finally decided to do something about the wall and got someone in using the DOFF hot water system: https://www.periodproperty.co.uk/forum/threads/paint-stripping-brickwork.14124/ (Scroll down that page to get to something that works.) The lime mortar won't have liked being wet for years and you will likely need new lime pointing after stripping. https://www.stripperspaintremovers.com/ can recommend paint stripping contractors. That's how I found mine.

Cement render at the front is annoying. It sticks too well to the bricks and the face of the bricks will be damaged when it is removed. If it is blowing the bricks will be full of water so the best thing would be to replace with lime render and limewash so the water can evaporate away. Someone else might be able to suggest a contractor. Or DIY is fairly straightforward and a lot cheaper.

You might well get away with only removing the cement render from below the windows. When the wall is covered with waterproof stuff all the way up to the top water will tend to rise up from the bottom looking for somewhere to evaporate until the whole wall is soaking wet after 50 or 100 years. Letting it evaporate somewhere should allow the whole wall to dry eventually so long as water isn't getting in from somewhere else like bad gutters. It'll take 30 years to dry so won't address any immediate damp or coldness problems in the upper floors.

 

[malcolm]

I forgot - the other water source is condensation from the rooms inside. That will be trapped in the wall but to a much lesser extent than the water coming up from the ground so won't it normally damage the render. It will reduce the thermal insulation of the bricks. Also it makes the wall more prone to mound both inside and outside.

 

[David]

Malcom
Many thanks for taking the time to reply and for the advice given. We don’t have much evidence of a problem with condensation or any sign of mould. However, we have got crumbly plaster and flakey paint on a couple of internal walls. These patches correspond to where it’s particularly bad on the outside.
Do you have any advice for removing the cement render? Are any power tools more effective than others. I have contacted several local specialists in lime render and restoration, but have received no reply from anyone! Presumably they are all really busy at the moment.
I’m leaning towards having a go at it myself, I’m not too bad with DIY but need advice really, My main issue is a lack of time to actually get it done!
Many thanks for your help so far.

 

[88v8]

Recent internal decoration - pre-sale - may be hiding some issues.

I've been using paint stripper to remove plastic paint and it's hard going. Malcolm has a better idea.

Lime specialists are often booked up months ahead.

To remove the render, try a bolster and big hammer. Then for the stubborn bits an SDS chisel https://www.screwfix.com/c/tools/sds-chisels/cat5920050 plus of course a suitable drill which you could buy or hire. I always like to buy things but that's just me.

If you're going to re-render you don't need to remove every scrap.

Protect the windows with hardboard and masking tape to avoid damage, and wear goggles.

Once freed of cement the wall will dry out at approx one month per inch thickness.

Ivor

PS as regards the non-replying specialists, I refer you to this reply from another place https://www.lemonfool.co.uk/viewtopic.php?p=518493#p518493

 

[malcolm]

It's occurred to me I'm planning to re-plaster only the bottom few feet of an internal cement rendered wall to try to help fix a damp problem. It's a different problem caused by a difference in ground levels between rooms.

As a rule I use an SDS drill on impact mode with a chisel attachment to chip off cement render. Battery powered ones are useless - it has to be mains powered. If you want a brick finish it's much more time consuming. Half of the brick faces will be pulled off by the cement but with care and hand tools (and slitting the concrete with a grinder every inch or so) the other half can be saved.

 

[David]

Thanks for your advice Ivor

Malcolm

Will you do the re-plastering yourself? Will you be using lime this time?

A brick finish isn't possible as I'm only intending to repair and re-render the lower part of the wall under the window cills.

 

[Cubist]

Hi David,

Until your latest post I had nothing of value to add and sadly my contribution now is a negative point. Lime and Portland based mortars will not 'bond' effectively at their boundaries. Consequently there will be fissures at the boundary that permit water ingress thus further damaging both the old and the new render and adding to the internal damp issues.

I'm afraid that the best strategies are kind of all or nothing - strip off and replace 'all' the render or repair the damaged sections using the same material as the original.

Sorry to be a damp squib and happy to hear from others that I'm wrong.

Good luck.

 

[David]

Oh dear. Back to the drawing board!

 

[malcolm]

When applying lime on top of concrete you risk a poor bond, but edge to edge is fine. There's a good chance of a shrinkage crack when the lime dries. Just fill it in with a fine lime mix.

I DIY my lime. My favoured mix is mixing building sand 50:50 with sharp sand then mixing in NHL 3.5 at a ratio 1 lime to 2.5 sand. I've used it for pointing and rendering. Put on base coats to bring the level to maybe 10mm below finished level and then a finishing coat to level.

 

[Cubist]

Malcolm is dead right, you can lay a lime mortar directly adjacent to and indeed contacting a cement render. Sadly though a chemical bond between them is, as I understand it, impossible. If the objective were to make cosmetic repairs to the render then, provided you remove all trace of the old cement render from the underlying brickwork, you can do this successfully. However, if your primary objective is to reduce/eliminate water penetration then the almost inevitable hairline gaps between the renders will defeat this aim.

How much of the existing render has 'blown' off? Also, have you conducted a 'tap' test on the remaining render to check for 'hollow' sounds?

 

[David]

There are some hollow spots. Not much of the existing render is coming off, it's mainly the plastic paint cracking and blistering. I'm going to take a few photographs and load them up tomorrow so you can take a look. I have resigned myself to tackling this myself as a DIY repair, so I'm going to need as much advice as I can get!

The internal walls on the front of the house are completely dry now, however there is evidence of them being wet in the past, probably from before the rotten wooden windows were replaced. With this mind I am thinking my primary objective is to make cosmetic repairs to the render, as it looks a real mess at the moment.

 

[a twig]

Externally could you use a small flashing at the interface between the cement render and NHL render, would get around your “leaky boundary” problem and probably still be cheaper than hacking off and re-doing the whole wall

 

[David]

Re-doing the whole wall isn't an option at the moment due to finances, even if it means that what I do now will just be a temporary, cosmetic fix.

I have attached a couple photographs that I took yesterday evening, which will hopefully give you some idea of the problems. As stated previously, there is nothing above the level of the ground floor windows, it's all on the bottom of the wall. The area to the right of the electric meter sounded very "hollow" when I tapped it yesterday.

I really appreciate the input I'm getting chaps.

Struggling to upload the photos for some reason.

 

[Cubist]

Hello again David,

Have you ever read 'The Art of War' by Sun Tzu? Its known as an excellent study for anyone considering a career in the military or business management and its also an invaluable resource for anyone who takes on a 'Period' property. My copy is kept alongside my Readers Digest Repair Manual - Complete Guide to Home Maintenance, which was published when I was still a lad.

Among Sun Tzu's many lessons are some concerning which battles to fight and when to fight them and there is an acknowledgement that there are some battles where the best strategy is to 'run away' as this may be the best way to ultimately win the war.

I'm not sure you are quite in that position yet but do beware. When it comes to render, like old plaster, there is the risk that once you begin a repair attack, unexpected escalations can occur - particularly if that attack includes a big hammer or an SDS chisel - how many of us can have failed to see the comedian nailing a picture to a wall only to see all the plaster collapse?

Its hard to make out detail from the photos provided but I can make out some cracks and patches where the surface of the render has fallen away. Provided the render in these immediate areas is not loose or frangible you could consider using a fine filler pressed into the cracks and maybe a cement based filler to 'level up' the surface of small patches like that in your last picture above.

On balance though I suspect that ultimately you will need to remove all of the old damaged/failed render and replace it with new material. If the existing render is in good condition above a certain height this need not be removed as with some care, it is possible to replace the failed section only. If you choose to go down this route and to use a lime based render to make the repair I, and others would be happy to offer suggestions and ideas for how best to do this.

Perhaps, for now, you might choose to simply accept the condition of the render as a feature of the rustic charm of a period property - and live to fight another day.

Don't hesitate to get in touch if we can be of more help or provide more detail/suggestions.

Cheers,
Cubist (aka Steve)

 

[David]

Many thanks for all the advice. You've certainly given me something to reflect on!

I'm going to give some careful consideration to my plans and return in due course. Thanks again to all who have replied.

David

 

[MatthewC]

If you do the lower part of the wall in lime then I reckon you could be succesful. However, if the wall has an impervious finish lower than the lime, the dampness simply emerges at the bottom of the lime and causes (over time) massive issues with the lime mortar. I had lots like this - there was a very hard layer of steel-like concrete along the base of several walls; at one spot the wallpaper was holding the popped lime mortar to the concrete!

 

[David]

I have decided to try and make a temporary cosmetic repair to the areas of crumbling render as seen on the photo above.

Could someone advise me what the lower 2 feet of the wall will likely be made of? There is a lip where the wall changes depth about 2 feet up the wall? I have attached a photo of the house taken before it was rendered which shows the lower section of wall isn't brick. Could this be old concrete?

Any advice would be appreciated. (Property to the right of the parked car)

 

[Cubist]

Is there any evidence of this same coating at the rear of the house? When was the house built?

 

[David]

The previous owner told us the house was built in 1796. On the rear of the property there is no coating/rendering at all. Just "plastic" painted brick walls, which I have been told will come off with paint remover and a steam cleaner lance.