External Render Choice

[andyrew1]

Hello

We have had some damp issues in our kitchen (standard victorian terrace). Following a damp survery the main culperate seems likely to be condensation (separate thread on that) but the state of the external pebbledash is far from ideal and is patched in a lot of places and generally pretty ugly so I am not against an excuse to replace it. The guy who did the survey suggested a silicone render but as he suggested plenty of dubious things in his reccomendations I am taking them all with a pinch of salt.

That being said the marketing on the silicone based render certainly does sound appealing. Our house being a terrace means all the materials and scafolding have to come through the house so a solution that does not require regular painting seems very appealing, and they make unsubstantiated claims about breathabiltiy So with the risk of being shunned from the forum the same day I have joined: considering that it seems we do not currently have sopping wet walls requiring a huge level of breathability is this a good enough compromise over a lime render that it seems will require much more regular maintenance?

Also very open to any other options or suggestions

 

[Feltwell]

Not sure if it was silicone or not, but my parents had a supposedly self-coloured render put on their retirement bungalow - it's a 1950's place with cavity walls so no breathability worries. Anyway, it looked OK at first but within 5 years we ended up painting the place anyway, it went very patchy in colour.

If you've got damp issues - even if they have possible multiple sources - and you're going to the effort of re-rendering it seems daft not to go with a breathable approach. Don't forget that you don't have to use limewash over lime render (though it looks fantastic!), there are breathable silicate paints out there that are long lasting. Not really my area of knowledge, I believe Keim silicate paints are well regarded, but others on here may know more.

 

[stuart45]

Finishes like K rend are advertised as being maintenance free, and never needed to be painted because of the through colour.
However if you look at the amount of K rend cleaning firms that have sprung up it tells you about the issues.
When people talk about breathability it depends on how breathable it is. Sand/cement render allows a certain amount of moisture through. 3/1 is considered the strength for an average sand mix to be close to being impermeable. However a lime render would be much more breathable.
Some lime mixes are more so than others.

 

[CliffordPope]

We had all the walls of our house re-finished externally about 8 years ago. It's a victorian farmhouse and was covered in old stucco which was pulling away from the wall in vaste and very heavy sheets, with a 3 inch gap behind in many places. We had it all hacked off - easy job, as it mostly just fell off when you looked at it, and revealed the original stonework and some nice brickwork around the doors and windows. We were originally going to just have it re-rendered and painted, but the stone and brickwork was so lovely we changed plans.
The front and rear walls were repointed entirely (with lime mortar of course), but the high gable ends were not really suitable for this treatment. One, a largely blank wall with only a few very small downstairs windows, is the one that faces the prevailing westerly winds, with intense driving rain part of the year. The other end had been badly hacked about fitting internal flue pipes and inspection chambers for sweeping and refinished with odd bricks and slabs of concrete. The experts (I think they were experts - they were a small firm who specialised in restoring period houses) advised that with the prevailing rain, the state of the other end wall, and the fact that both walls were heavily impregnated with ancient soot staining from numerous chimneys, and that the staining would always show through without special treatment. Blackened stonework would not clean up and would in any case leach through again and render would not stick well to tar. It was also an enormous and very high and expensive area to repoint. So we had stainless steel mesh attached to the walls and then rendered with a thick lime-based mix, and very expertly smoothed flat.

The end walls were then sprayed with Tyrolean mix. This used a hand-held machine looking like a miniature muck-spreader, and basically splattered a coat of lime and sand mortar, which dried to a lovely beige colour which exactly matched the stonework on the other two walls. It needs no maintenance or further coating at all.
The sandy finish looks natural, and changes its shade subtly with humidity, as does the stonework.

The principal elevations at front and back show off the stone and brickwork.

My only observation on the pointed stonework, apart from looking lovely, is that it is not true that stonework pointed traditionally is weatherproof. Rain poured through, as lime mortar appeares to be entirely porous like a sponge. It was very disappointing, as everything I had read, and the assurances of the experts, said that it would let the wall "breathe" and so stay dry inside. This was simply untrue.
So the end result was that I sprayed a liberal coat of "No Nonsense" Screwfix silicone sealant on the front wall, and it entirely stopped the water. It works really well, and the house is still dry 8 years later.
I have been told I should have adopted the local traditional method - farmers who don't care what their houses look like nail sheets of corrugated iron over their walls

 

[CliffordPope]

 

[Cubist]

I have been told I should have adopted the local traditional method - farmers who don't care what their houses look like nail sheets of corrugated iron over their walls

Thats a lovely house Clifford and the thought it was coated with corrugated iron for however long is just appalling. Sadly our place suffered the same fate at some point but that abuse was removed 30+ years ago. Farmers - frugal pragmatics its claimed but, in this context, vandals and hooligans in my book.

 

[Feltwell]

I have been told I should have adopted the local traditional method - farmers who don't care what their houses look like nail sheets of corrugated iron over their walls

Lovely place Clifford!

Yes, I've seen plenty of farmhouses with that. Not as bad though as one place I saw in Yorkshire - the entire house had been painted in tar to seal it! Looked bloody awful, and the farmer (the son of the culprit) said the house was still damp 40 years on and he cursed his father for ruining the place!

 

[Cubist]

Some years back I happened to ask a neighbour why he had painted only some of the internal panels of his garage/shed. He told me that the corrugated sheets he'd used to build the place had been recovered from our place when it was removed. Seems the previous owners had painted the exterior to emulate a black and white cottage.

 

[CliffordPope]

"the entire house had been painted in tar to seal it!"

I've seen fishermen's cottages immediately next to the sea entirely tarred, but that's a bit different. I'd assume different rules apply if the sea regularly breaks over your house.