Advice needed on Rendering a Garden Flint Wall

[mike912]

Hi all,
I would like to know what is the best process for rendering my garden flint wall. (Step by step if possible)
What would you recommend;
Sand/Cement mix?
How many layers of render?
Do i need a wire mesh for support?
Do i have to worry about damp prior to the job?
What are the best materials for the job?
What are the possible 'got ya' to look out for?
The wall it self is fair solid, but there are a few section that are lose.
Would like to get a much smoother finish.
You can see the size and state of it here http://www.flickr.com/photos/53006909@N02/sets/72157625745454752/

Thanks for your time and advice..

 

[Micilin]

Mike, I've been waiting for someone to answer!


It's not a background I've rendered.

Do you have any cracking?

Is it all sound bar a few small areas?

I'm presuming it's all backed up with soil behind?

Do you get a lot of water there - running down or over the wall: or coming through?

Do you have some kind of gully or run off anywhere - is that raised patio sloped away from teh back wall?

Do you propose some kind of capping or similar at the top?

 

[roughcaster]

Mike, I've been waiting for someone to answer!


It's not a background I've rendered.

Do you have any cracking?

Is it all sound bar a few small areas?

I'm presuming it's all backed up with soil behind?

Do you get a lot of water there - running down or over the wall: or coming through?

Do you have some kind of gully or run off anywhere - is that raised patio sloped away from teh back wall?

Do you propose some kind of capping or similar at the top?

Just to add to what Micilin said, i think it would spoil it if you rendered over that. It wouldn't last very long either, by the time water ran down it, mould/salts would grow onto it/through it,, it would be difficult to keep clean, frost would damage it, etc etc. Not an easy call.

 

[roy c]

I looked at the pictures and never having seen a flint wall I thought it would be a shame to render it too. But after a closer look I think that if you pressure-washed the wall and the whole area (which looks like it has been done very well) you could have some pieces of natural local stone cut to fit onto the steps and I think that would make a "hell" of a difference and you may change your mind about rendering.

You would be quite surprised how a power-washer would clean all the algae off and bring the natural beauty out of flint and the steps...

Maybe it would be an idea to have the wall with the larger stones in hacked out and repointed. I would get a reputable local stone-mason to give you some advice....

 

[spc]

ok, your answer wil determine what cause of action I would take.

what are the flints bedded on? Lime or cement?

 

[Micilin]

I would guess something like a 6:1:1 sand:cement:lime.


It's personal taste, but I think the render would look good for 6 months or a year , and as the lads say it will deteriorate . The factors I mentioned above mean that IMHO it will be hard to get it done to last. I can see it blowing after a winter or two. If you get the repairs done in keeping it will be cheaper, and your maintenance will probably be limited to a clean down every couple of years.

 

[spc]

if it was bedded in on lime, Then an Nhl 5 mortor mix would still let the wall breathe but as a trade off it will be covered in algae in 6-8 months.

It would neeed to built up in 6-8mm layers as ther is 0 suction in the flint.

I agree with previous posts, rake out and re point

 

[Possel]

ok, your answer wil determine what cause of action I would take.

what are the flints bedded on? Lime or cement?

I note that Mike912 has not replied to this very important question. I think the general message is that most people think "why do you want to render it?" If there is some technical issue, then it would be good to hear what that is; if it's just for aesthetic reasons then it seems a shame that such a feature would get transformed to something quite bland (at best).

Of course, if the property is listed or in a conservation area, then rendering such a feature would actually be illegal!

 

[Alastairreid]

To render that wall would make it look cheap and nasty.
i would retain the wall in its present state, repointing and re-bedding as required.

 

[Micilin]

ok, your answer wil determine what cause of action I would take.

what are the flints bedded on? Lime or cement?

I note that Mike912 has not replied to this very important question. I think the general message is that most people think "why do you want to render it?" If there is some technical issue, then it would be good to hear what that is; if it's just for aesthetic reasons then it seems a shame that such a feature would get transformed to something quite bland (at best).

Of course, if the property is listed or in a conservation area, then rendering such a feature would actually be illegal!

From a technical point of view -

There is soil behind the wall, so water will be coming through. You would need it well keyed and waterproofed. All of this could be done with SBR.

You could also have 'weep holes' in it to allow some water to come through rather than build up behind.

To stop water running in behind the render ( between render and wall) and down along the render the wall would need to be a bit higher than the ground behind it , have a cap which would be wide enough to have a drip which would extend past the render

Cracks in the wall will probably lead to cracks in the render are they a result of pressure from what's behind it, movement , poor building ?

Cracks in the render will look worse than hairline cracks (or bigger) in new pointing. They will also let water in . Even if the render is waterproof, the water in the crack will freeze , expand and do damage.

They would need meshing , but without sorting out the cause, you are just moving the crack

I'm assuming the patio/ledge slops away from the wall. If not , you'll have water at the base of the wall doing what water does over time. Again, sbr /water proofer will make the render impervious to soaking in water, but the crack where render and patio meet will be affected by frost as above, but over a long time.

Now, as ever, it's down to individual taste vs practical considerations.

If Mike wants a nice even render, will prepare and sort out the issues, he can have a nice rendered wall. If he's happy with the flint, it'll be easier to sort out.

IMHO a bit of moss and algae on an old flint wall is more in keeping with the setting than the algae and moss that you will have on the render


JUst me.

 

[mike912]

Sorry for the late reply, I have been a bit detracted with internal house renovations. No rest for the wicked...
With all that behind me now, I am now focus on my flint wall.

With all the generous feedback the consensus seem to be just clean and re-pointing the original flint wall, which I thought might be the bigger job.

Answers to questions;

Do you have any cracking? Yes some flint has fallen out and the flint wall seems too bowed in a few places.

Is it all sound bar a few small areas? Not sure what that is?

I'm presuming it's all backed up with soil behind? Yes, a lot

Do you get a lot of water there - running down or over the wall: or coming through? I guess so; I think that might be one of the causes for it to bow, that and the amount of earth behind it.

What are the flints bedded on? Lime or cement? Not sure, how can I tell?

Thank you for your previous advice and tips!