More render confusion

[JoceAndChris]

Do you think I should have the outside of the music room rendered in lime or cement? It is a 1930s extension, brick built, encased in the same thick cement that's covered the Georgian stone built house. I imagine the whole lot was rendered in the 30s.

The render has failed over the entire property and in my view needs to all come off and be redone. Of course lime must be used for the Georgian sections.

At last the funds are almost there for this and I need to send off my application for LBC, and don't know what to say about this bit. I want it to match, of course, and I'm not sure how well limewash would stick to the Sandtex that's there currently, if I were to leave it.

Original stone facade

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Brick built extension

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Thanks for any views.

 

[Nigel Watts]

Joce

Limewash won't stick at all well to Sandtex so it you don't re-render, and you want it to have the same finish, you will need to strip the paint off first. The limewash may stick to the cement render underneath, but if that's what you want to do it would be worth doing a test to confirm.

The 2000s extension to my 1840s house was rendered in cement and covered in Dulux. I decided not to strip the vinyl paint when I limewashed the older part of the house, but repaint the 2000s extension in Magnolia emulsion, a significantly paler colour than the limewash thus accentuating rather than trying to hide the difference, and leaving the modern extension looking clean and new in contrast to the rather more distressed appearance of the Victorian fabric. I am not displeased with the result.

 

[JoceAndChris]

Thanks Nigel. I hope you'll let me pick your brains more and more when the job is underway, you know I want to have exactly the same finish as yours! Good choice to do your modern bit a bit different; I did think it looked lovely and a good contrast to the 1840s bit in your recent garden pics. I think because you've made the choice to have the architecture firmly of our time, to do the extension in a modern emulsion, but cream, is the logical course of action. Here, though, Miss Burroughs went to great pains to blend the extension in with the architecture and make it all look harmonious. It must be the same finish, which will be scored to resemble ashlar blocks. I might be able to get a colour match to the copperas limewash in a modern emulsion, I don't know.

Thanks for the tip about stripping - as I say - I think the very cracked music room render really does need to come off and be redone even if we choose to have it redone in cement.

 

[Feltwell]

Is it cavity construction or not Joce? In the 1930's it could have been either.

No cavity means that ideally you want breathability.

I'd be tempted in any event to render it in the same finish as the rest of the building - it's a sympathetic extension and deserves to blend in as best as it can to the original house in my opinion. I wouldn't have thought it would add that much to the overall cost.

 

[Zebra]

For what it's worth I'm with Feltwell. It's the labour rather than the materials, largely, that costs you the money when it comes to rendering, so you might as well have what you want, without it adding significantly to the cost.

Rather than be guided by contractors, I did my own research into which materials were right for the job, and then found contractors willing to work with me and do it my way (with me taking responsibility for the result!).

 

[JoceAndChris]

Thanks so much for the responses, great to be guided by people with such a wealth of experience and good taste!

Feltwell - not sure if it's a cavity wall or not - there are air bricks top and bottom - does that give anything away?

But lime it is then. Gareth has also advised lime as being unlikely to hurt. Fab. 8) That means I can get a completely harmonious finish.

Zebra - good plan to shape your project the way you want it and get them doing your bidding. I expect it means you have to hover about and check work a lot? There are so many out there who can't be trusted to use historic materials

 

[88v8]

If it's a cavity wall it will be thicker than the early solid, although only by an inch. Perhaps 10" vs 9". Plus plaster plus render.
A surefire way to tell is to drill with a long masonry drill and see what happens after you go through the first 4" or so. Or, just knock off a some render, if the bricks are all stretchers - lengthways - it's cavity, if they're a mix of headers and stretchers, it's solid.

If cavity, here's your chance to get it insulated - blown rockwool is the least likely to cause damp problems.

As to render, no harm will be done by lime, but harm might be done by cement.

Messy process, the flowerbeds against the house will get trashed. Any plants you value, take cuttings or dig up in the autumn.

Ivor

 

[JoceAndChris]

Thanks Ivor, that's all very useful to know - in that case I'll know whether or not it's cavity when the render is off.

The insulation is a really interesting idea, I wonder if the whole property could be insulated externally and remain breathable? Must investigate, and also find out the costs.

Good point regarding the plants, the borders up against the house were planted by the previous owners and excepting for the 7 ft lollipop bay there's nothing I'd cry to lose. Anyway, I'm not keen on yet more herbaceous borders - the garden is large and I'm fairly decided it's going to be gravel up against the house with a simple pattern of box balls and lavender.

 

[Zebra]

Zebra - good plan to shape your project the way you want it and get them doing your bidding. I expect it means you have to hover about and check work a lot? There are so many out there who can't be trusted to use historic materials and methods.

Please forgive me if this is a little ageist, but both my render contractors and my roofer were quite young, late 20s / early 30s, with their own small businesses. Perhaps that's nothing to do with it, perhaps they were just nice people, but they were really interested in what I was doing with the house, loved doing something a bit different, willing to let me take the lead, willing to ask if they weren't sure, and didn't act as if they knew best. And in return I didn't hold them in the least accountable when it all fell off in the night! (Supplier's error!) But I'm sure you've chosen an excellent firm to do your works.

 

[Zebra]

The insulation is a really interesting idea, I wonder if the whole property could be insulated externally and remain breathable? Must investigate, and also find out the costs.

Yes indeed! But it will affect your window cills, reveals and openings, and you have to consider whether you have enough roof overhang. The insulation has to be quite deep for the effort to be worthwhile, just a thin layer won't make a lot of difference. I did quite a lot of research into this, looking at woodfibre insulation and woodwool, but there's also limecrete, EcoCork, and many other ideas.

 

[JoceAndChris]

Thanks Zebra. Sounds like your workmen were a joy - lovely when it's like that.

I've been reading about the products you mention and it sounds very interesting and worthwhile, but I only have an inch and a half - that's the thickness of the current cement render. Any thicker and it will start to impact on the windows and also the chestnut guttering and crenellations. Hmm. Must make some phone calls to to the sellers of these products. Thanks again for alerting me.

 

[88v8]

Thanks Ivor, that's all very useful to know - in that case I'll know whether or not it's cavity when the render is off.

The insulation is a really interesting idea, I wonder if the whole property could be insulated externally and remain breathable? Must investigate, and also find out the costs.

Good point regarding the plants, the borders up against the house were planted by the previous owners and excepting for the 7 ft lollipop bay there's nothing I'd cry to lose. Anyway, I'm not keen on yet more herbaceous borders - the garden is large and I'm fairly decided it's going to be gravel up against the house with a simple pattern of box balls and lavender.

The south wall is usually the warmest area of the garden. Shame not to use it for tender plants n climbers. But if you prefer weeding gravel, well we all have our foibles.

External insulation - complete waste of money and will ruin the appearance of the house. A good product to sell to numpties living in square brick boxes.
See what it says here - need to be 2-4" thick, plus render.
http://www.which.co.uk/energy/creating-an-energy-saving-home/guides/solid-wall-insulation/solid-wall-insulation-costs-and-savings/
And, payback time up to 27 years :shock: which is a lie anyway, as it disregards loss of interest on the capital. The actual payback time is never. Never.

Worth getting the cavity done though - if any - has a quick payback and no visual impact.

That reminds me, must sign up with a new dentist. Wish I hadn't thought of that... :?

Ivor

 

[Roger H]

External insulation - complete waste of money and will ruin the appearance of the house. A good product to sell to numpties living in square brick boxes.

Not strictly true. Ecocork comes in at 40mm thick - http://www.mikewye.co.uk/ecoCORK_insulating_Render_onto_cob.htm

 

[JoceAndChris]

The south wall is usually the warmest area of the garden. Shame not to use it for tender plants n climbers. But if you prefer weeding gravel, well we all have our foibles

The south bit is the tiny extension where the daffodils are, yes to climbers but it is on a very exposed and windy hilltop and nothing is particularly happy there. It's fronted by a lawn, a patio, and a shrubbery section that I'm going to develop into a large pond, this is going to be the show stopping part of the garden. I just need the bit up against the house to be easy, I now have a team of three gardeners who come for one morning a week and I work on it every single day and still we are just scraping the surface!

 

[Gareth Hughes]

I think Ivor is misunderstanding what is meant by insulated render in this particular case - not sheets of insulating material fixed to the outside wall and then rendered over the top (increasing the overall wall thickness and playing havoce with openings and detailing generally, but a lime render incorporating an "aggregate" of insulating material (hemp, or cork chips) in the mix, applied like a normal render base coat, to normal render thicknesses.

 

[JoceAndChris]

That sounds ideal.

 

[Zebra]

External insulation - complete waste of money and will ruin the appearance of the house. A good product to sell to numpties living in square brick boxes.
See what it says here - need to be 2-4" thick, plus render.
http://www.which.co.uk/energy/creating-an-energy-saving-home/guides/solid-wall-insulation/solid-wall-insulation-costs-and-savings/
And, payback time up to 27 years :shock: which is a lie anyway, as it disregards loss of interest on the capital. The actual payback time is never. Never.

Certainly not to be recommended in all cases, but in my case I was going to be re-rendering anyway, and re-roofing, and having new windows, so could manage to incorporate the extra 100mm of thickness, and it has made an enormous difference to the warmth of the room.

 

[MdB]

We have put 60mm of Kingspan on the outside of our 70's lump and again it has made an enormous difference. Very glad we did it.
I'm going to be rather interested to see what our electricity (heating) bill is next winter.

 

[88v8]

I think Ivor is misunderstanding what is meant by insulated render in this particular case - not sheets of insulating material fixed to the outside wall and then rendered over the top (increasing the overall wall thickness and playing havoce with openings and detailing generally, but a lime render incorporating an "aggregate" of insulating material (hemp, or cork chips) in the mix, applied like a normal render base coat, to normal render thicknesses.

Ahhh, that might be a different matter. We used a hemp first coat on our internal lime plaster for that reason.

Ivor