(Dis)coloured render

[paulb33]

Hi All,

Restoration of my 1901 Arts & Crafts house continues. I've finally secured LBC for the timber windows. And now I need to hurry to clean off the brilliant white plastic paint from the render. A job best done before my nice new windows are in.

I spent yesterday cleaning it. Three stories up in a gale with a pressure washer, immersed in steam. I probably need a new hobby. Anyway, the paint is coming off and reveals a lovely, sound, cement-based pebbledash, perhaps containing some lime (its very hard and fizzes).

Anyway, I'm intrigued by its two-tone colour. Most of the render appears as a tan colour. Perhaps an adsorbed limewash???? But, it changes to a dark brown colour under the eaves.

Anyone any thoughts on this? It doesn't appear to be differential drying: the wind has dried out the render and its now stable. It almost looks like a purposeful attempt to accentuate shading under the roof overhang. The timberwork was originally dark brown (and will be restored to this). Could this be?????

Value your ideas...

Cheers,

Paul

 

[DJH]

Was pebbledash ever painted or washed Paul? I don't envy you that job in this weather or any weather in fact...

Doug

 

[paulb33]

Not sure, Doug. I'd like to think it was plain render originally. Most heritage bodies seem to prefer that plain Edwardian cement pebbledash is left unpainted. Suggesting that's how it was intended. Really difficult to tell. There's a layer of bright yellow limewash, which looks like an after thought. I certainly much prefer the bare pebbledash, which looks a lot better against the orange brickwork. Its the darkened render under the eaves that intrigues me. If this was purposeful colouration, then it indicates that the render was intended to be unpainted. Its similarly dark on the window reveals...
P

 

[plasticpigeon]

I have no idea, but my guess would be that it was not purposefully painted that way as the transition is not sharp but a blend. I've seen this effect on stonework, where an overhanging part of a door surround or cornice will be pale where the rain hits it, but darker underneath where the rain doesn't hit it. I assume pollution gets washed off the exposed surfaces but not the surfaces that the rain can't fall on. It would suggest to me that that pebbledash was left unpainted though. i am looking forward to seeing your house after the changes you are planning to make. It sounds like you are going to great efforts to get every detail historically correct. Are the windows you are getting exact replicas of the originals? What did you decide about the glass???

 

[paulb33]

I have no idea, but my guess would be that it was not purposefully painted that way as the transition is not sharp but a blend. I've seen this effect on stonework, where an overhanging part of a door surround or cornice will be pale where the rain hits it, but darker underneath where the rain doesn't hit it. I assume pollution gets washed off the exposed surfaces and not the surfaces that the rain can't fall on. It would suggest to me that that pebbledash was left unpainted though.

That makes very good sense! (And, I selfishly welcome the vote for unpainted render, which I much prefer... )

Any other thoughts on this would be very welcome..

Paul

 

[parkview094]

Was pebbledash ever painted or washed Paul? I don't envy you that job in this weather or any weather in fact...

Doug

Oh yes. This is a subject now most dear to my heart. From the Gidea Park exhibition brochure, many houses are described as:

"..covered with self-coloured cement, roughcast..."

"...cement roughcast, distempered cream.."

"..roughcast and tinted with limewash".

You don't think the change in colour is just a difference resulting from how exposed the walls under the eves were vs. the rest of the wall?

 

[DJH]

That's interesting. I can't see why though that they would colour over the natural finish of the stone in the pebble dash. It's a matter of taste and choice of course but it does make it difficult when trying to return our properties to their original intended state.

I agree about the shelter line under overhanging parts being a different colour than those which are exposed to weather and sunshine.

Doug

 

[paulb33]

Was pebbledash ever painted or washed Paul? I don't envy you that job in this weather or any weather in fact...

Doug

Oh yes. This is a subject now most dear to my heart. From the Gidea Park exhibition brochure, many houses are described as:

"..covered with self-coloured cement, roughcast..."

"...cement roughcast, distempered cream.."

"..roughcast and tinted with limewash".

You don't think the change in colour is just a difference resulting from how exposed the walls under the eves were vs. the rest of the wall?

Oh, now you've wet my apetite. Its amazing how little information exists about the original treatment of cement render from this period. Do you have a link to this brochure.

I do think the weathering/pollution is the likely cause, as Plastic Pigeon speculates. But, this is semi rural location in Penarth, a seaside town 5 miles from Cardiff (not smoggy London). Curious as to what is causing this darkening to this extent.

Regardless of cause, does this mean it was likely unpainted?

 

[paulb33]

A few doors up. I guess its weathering/polution...

 

[DJH]

Some thoughts on rendering new walls from ‘The Little Things That Matter’ series Vol II published by the Architectural Press 1925…

…….and the use of a facing of stucco or roughcast has come into fashion again after being banished as a reprehensible sham during some part of the Victorian era.

A genuine preference for the lighter colour of a wall coated with roughcast may make its employment worthwhile, but in places where soot and grime are certain to be deposited on it, it’s “cheerful” appearance is likely to undergo a very serious transformation to a tint more depressing than that of any moderately pleasing type of brick.

Where the colour of the roughcast is modified by the use of added washes of pigment the periodical renewal of these will also be costly, and in dull, rainy weather light coloured buildings become sodden looking and unattractive just when the need for a cheerful appearance is greatest.

My own view is that lime/whitewash when applied to roughcast, even with the greatest care, will settle in cavities much thicker than required and will cure to dust. On raised surfaces it will be so thin it will wash off in rain leaving the roughcast grinning through.

Doug

 

[paulb33]

A genuine preference for the lighter colour of a wall coated with roughcast may make its employment worthwhile, but in places where soot and grime are certain to be deposited on it, it’s “cheerful” appearance is likely to undergo a very serious transformation to a tint more depressing than that of any moderately pleasing type of brick.

Where the colour of the roughcast is modified by the use of added washes of pigment the periodical renewal of these will also be costly, and in dull, rainy weather light coloured buildings become sodden looking and unattractive just when the need for a cheerful appearance is greatest.

My own view is that lime/whitewash when applied to roughcast, even with the greatest care, will settle in cavities much thicker than required and will cure to dust. On raised surfaces it will be so thin it will wash off in rain leaving the roughcast grinning through.

Doug

Apparently, the tower of St Albans Abbey was originally rendered, way back when.... Its use in Arts & Crafts was based on 'time tested' workmanship (apparently)... Its use in speculative pot-war housing estates did more than anything else to discredit these lovely Edwardian houses.

Good article here: http://www.buildingconservation.com/articles/pebbledash/pebbledash.htm

I'm with you on the lime wash, Doug. Looking at the wall, its hard to imagine achieving a sufficiently thin layer to cure. I'm wondering if Beekosil silicate paint is a good compromise. Certainly, what I want to avoid is the horrible slightly undulating band of brilliant white plastic paint.

 

[paulb33]

i am looking forward to seeing your house after the changes you are planning to make. It sounds like you are going to great efforts to get every detail historically correct. Are the windows you are getting exact replicas of the originals? What did you decide about the glass???

The windows are based on the originals. I'm driving the joiner crazy. Mind you, everyone thinks I'm crazy not initialling DG. See comments on the attached local news blog. :lol: I chose not to enter the debate about the green credentials of plastic windows.

http://penarthnews.wordpress.com/2014/01/12/classic-penarth-villa-goes-back-to-the-future/

We have some photos from the 70s that show the windows. I'll be installing single glazed float glass. I couldn't justify the high cost of heritage glass in the relatively small panes. They can always be changed later....

 

[malcolm]

I can't add much apart from my place had a new frontage in about 1925 with a pebbledash style finish for the panels in a new tudor revival wood frame on the upper floor. Thanks for the link - very useful for me. Photos from when the frontage was applied appear to suggest the finish was originally left natural. It looked really dark and ugly. Less than 5 years later (so far as I can date the photos) the render was painted white.

I don't know whether this was a fashion thing or whether they were just waiting for the render to dry out before painting it. The window frames appeared to change colour at the same time.

My view on these things is to go with what you think will look nice and try to protect the building. It is a good historical approach as that's what people did in the past (apart from the protecting the building part).

 

[88v8]

I'll be installing single glazed float glass. I couldn't justify the high cost of heritage glass in the relatively small panes. They can always be changed later....

Put in 10% heritage. It will add some sparkle, and give you an incentive to replace the rest.
Not that you ever will.... do you seriously imagine that having installed, puttied and painted you will ever get the glass hacked out and replaced? Hurrr.

Now or never. Never.

Ivor

 

[plasticpigeon]

Paul, I hope your joiner manages to recreate the proportions of the original windows, as there is a bit of a trend at the moment of making flush casements with very heavy frames which look all wrong. I also often see flush casements put in old houses where the originals would have had the mullions (I believe that is the correct term) between the casements much more in relief, although in your case the casements look like they were originally flush with the frame. I have collected quite a few pieces of wavy glass recently. If you are ever passing Birmingham you can have them.

 

[paulb33]

Paul, I hope your joiner manages to recreate the proportions of the original windows, as there is a bit of a trend at the moment of making flush casements with very heavy frames which look all wrong. I also often see flush casements put in old houses where the originals would have had the mullions (I believe that is the correct term) between the casements much more in relief, although in your case the casements look like they were originally flush with the frame. I have collected quite a few pieces of wavy glass recently. If you are ever passing Birmingham you can have them.

Bless you PP. That's really very kind.

I'm going to see how the budget holds up, before deciding on the glass. At the moment its modern glass, but could stretch to wavy in some of the most prominent windows. We have a couple of original windows to base the design on and I'm making myself a PIA fussing over the details.

Here's one such window. This side opening pair is to a bathroom installed in the 60s. Its been sealed shut and top opening lights have been added. But, it provides a good template.

We're lucky in that the windows are really quite crude. So, hopefully, we can get this right. 33 windows to be made, after all..

Paul

 

[paulb33]

My view on these things is to go with what you think will look nice and try to protect the building. It is a good historical approach as that's what people did in the past (apart from the protecting the building part).

Good advice, Malcolm. I'm exploring what Beeckosil silicate paint can do in that regard. http://www.lime.org.uk/products/wall-paints/external-paints/mineral-paint-ty-mawr-range/

The owner's of Voysey's Perrycroft in Malvern have been helpful in my research. They speak highly of Beeckosil having chosen to use it instead of lime wash when restoring the render. In their case, they chose to overpaint the modern plastic paint given the scale of the job and the damage that removal was doing. They did a wonderful job, I think you'll agree. Gillian Archer has also restored the gardens. Its spectacular and I can only dream of achieving this kind of finish.

Interior and exterior photos from Country Life, here.

http://www.countrylifeimages.co.uk/Search.aspx?s=perrycroft

 

[paulb33]

More images here... Spookily, I recently learned that my grandmother worked in Perrycroft for the original owners. My Dad's from Malvern and I remember looking down on it from British Camp as a small boy. It must be fate.. :wink:

 

[DJH]

The last picture shows evidence of underside lead sheet corrosion caused no doubt by warm moist air in the roof leaking out under the hips and ridges, condensing under the lead coverings and converting to lead carbonate. This in turn is washed down over the roof by rain causing those unsightly white stains. They knew about this problem in those days but did nothing to counteract it...

Doug

 

[paulb33]

The last picture shows evidence of underside lead sheet corrosion caused no doubt by warm moist air in the roof leaking out under the hips and ridges, condensing under the lead coverings and converting to lead carbonate. This in turn is washed down over the roof by rain causing those unsightly white stains. They knew about this problem in those days but did nothing to counteract it...

Doug

Thats very interesting, Doug. I suppose sealing the inside of the roof would create other problems?

The leadwork at ridge line is lovely.