Do I need lime render on this 1920's house?

[Wistful20]

Hello,

I'm trying to organise work on or 1920's semi. The render at the front is in serious need of sorting out, but the back is also blown, if not as badly. I organised for someone to look at it. We have already replaced some windows and I've also been trying to sort quotes for the roof, which may need to be replaced, hence the delay despite the condition of the render. It's only part rendered at the front and fully rendered at the back, so only two sides need doing.



Because the house was built in the year 1920 and seems to have lime mortar, I assumed originally the render was most likely lime and that it would be best to use lime when we re-rendered if that was what was used originally, even though what's on it now is probably cement. I have therefore been looking for tradesmen with experience with lime. We don't have any issues with damp or leaks that we are aware of at present. The house has a cavity wall and the last owners had this filled with insulation.

The tradesman who visited told me that the house would never have had lime render and would have had cement render as the 1920s was a transition period into using cement. They advised that we should use silicone based render instead, and that there was no benefit to using lime. They told me that we didn't need to do much repointing as they could just do the few bits at the front where the mortar is crumbling out to dust from under masonry paint, but I'm worried other areas are in terrible condition under the paint and render. I asked if the pointing was deteriorating so badly because it had been painted and the exposed brick that is unpainted isn't like this. I was told no. They said the type of brick used didn't breathe so the mortar didn't need to either. He was more worried about removing an air brick and replacing it with a smaller one higher up despite it having been where it is probably longer than I have been alive and not causing any issues. It looked a bit dirty from when I'd cleaned the paving next to it, but it wasn't blocked in anyway nor anything a quick sweep or even hoovering wouldn't fix. He also thought there might be asbestos under the render, which seemed odd to me, as while not a trades person myself, I used to work for a construction company and I would tests people at interview for ability to identify potential asbestos. I believe between render and the brick on an external wall on a period property is not a common location for it to be found, which has made me question the rest of the guidance I received.

I'm going to organise some other quotes anyway, but I wanted to know if this chap was potentially right about the house never having had lime render and it not being necessary, as then I will not look specifically for tradesmen that work with lime.

Any advice on the render, the pointing or what to look for in a tradesman for this task would also be greatly appreciated.

 

[larry]

We have a 1920s house and it has/d original cement render. But it was unpainted. But then some wally painted it with standard masonry paint and we had penetrating damp a few years later, I presume after water got through cracks but couldn't dry out through the paint.

Hacked off the render and redid it in NHL based render painted with silicate paint. Others on here will recommend putty based render with limewash on top.

The bricks were in a dreadful condition underneath and it was very obvious where the water had got through when we hacked it off.

Only 2 years since but no troubles since then.

We have fairly shallow foundations and lime is more forgiving with movement/cracking

 

[paulc]

We have a 1920s house and it has/d original cement render. But it was unpainted. But then some wally painted it with standard masonry paint and we had penetrating damp a few years later, I presume after water got through cracks but couldn't dry out through the paint.

Late 1920s build here. Just the upper half is rendered. Originally, it was a thick, hard base coat of cement with a lime based rough cast top coat. Over the years, Sandtex type paints had been used. Patches of the rough cast had disintegrated and fallen away and was starting to look very tatty. A couple of years back, decided to remove the rough cast (much of it came off very easily with an air hammer & diamond cup wheel). The cement base coat still firmly attached and only a few cracks to grind out and patch. With a cement base coat, breathability is out of the window, so I just put a skim of a thin cement render on top.