Advice on repairing/re-rendering s&c render

[yocky]

Hi all, hope you don't mind a civilian posting here.

I recently bought a detached house that has been extended with blockwork from its original single skin brick construction. The whole property has been rendered with sand and cement, presumably to create a consistent look, but this rendering was clearly very poorly done (looks terrible) and maybe was an unsuitable material (clear cracking).

There is much evidence of damp inside the house, most noticeably on exposed brickwork in one room where a damp meter went ballistic when applied. A survey did point all of this out before purchase, so I'm not distraught at this point. I do need to get it sorted though and as it's likely to be a big spend I'd like to make sensible decisions at this point.

2 contractors have looked already. One from a flash operation who seem very professional but seem keen to sell me an EWI STO solution. Haven't had the quote on that yet. Another said I should only go with a lime based render because of its ability to allow the already damp walls to dry after rendering and then he would apply a coat of Endura finish, which as far as I can tell is a very expensive paint. (The second seemed to suggest he wouldn't even need to put scaffolding up which seemed strange for a 3 storey house)

2 traditional plasterers who I found via a well known recommendation site are visiting this weekend and I fully expect them to recommend K-rend or something similar.

Can someone shed some light on the various options available to me? I'm feeling a bit in the dark here on a job that has the potential to go tits-up if I make the wrong decisions.

In particular;

• Do the specifics of my house require a specific type of render?
• Does all the render have to come off, or can the parts than are clearly solid stay?
• Will one type of render allow the house to dry out better than another?

Anything else you can add is appreciated.

 

[Vincey]

Welcome to forum
There is a lot of questions there
The more knowledgeable spreads will be along shortly to give a more in depth technically correct answers to your queries..

My advise is go with the quote that feels right the person who feels honest and real.
9 times out of 10 your gut feeling is right..
That's what I do.

 

[themucky1]

Hack off the old render whether it's solid or not anyone who's prepared to render over old render will be prepared to take your cash and run like f**k, if you don't want Ewi don't have it and don't let anyone talk you into it it's your house not theirs although Ewi is possibly more beneficial over its life expectancy than other renders, the fella or firm who's prepared to work off ladders bin them off also how is it possible to render a house off ladders? Where are you located the may be someone from this site that's near and will point you in the right direction, there is a local firm to myself that work off ladders and I've no idea how they do it I've seen some of there jobs and there just about s**t


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[Jgreenplastering]

Hack off the old render whether it's solid or not anyone who's prepared to render over old render will be prepared to take your cash and run like f**k, if you don't want Ewi don't have it and don't let anyone talk you into it it's your house not theirs although Ewi is possibly more beneficial over its life expectancy than other renders, the fella or firm who's prepared to work off ladders bin them off also how is it possible to render a house off ladders? Where are you located the may be someone from this site that's near and will point you in the right direction, there is a local firm to myself that work off ladders and I've no idea how they do it I've seen some of there jobs and there just about s**t


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Agree with all of what the above says except hack off.
If the render is in poor condition then it definitely needs removing however if it is on solid then you can be causing more damage trying to remove it then leaving it on.
A strong render can take off some of the brick face and disturb mortar joints resulting in a weakened substrate which isn't good.
We've been rendering over solid render (bare and painted) for a good few years now with fully meshed and pinned base coats and so far no problems so it can be done. You just have to make sure it's suitable for that application before you do it.

 

[yocky]

Thanks for the replies so far.

Can anyone comment on the different render types? Does the fact that my walls are pretty damp already affect the render choice?

 

[vfr12]

If your walls are very damp it means it's exposed to severe weather conditions or the existing render is not up to standard which is very hard to say without seeing it. Hacking off will cost you almost the same amount as installing EWI , but not with the benefits of it. My advice- see what the sto guy has to say and breathable internal render.

 

[Rigsby]

Sto is one of the best in manufactured renders but it carries a premium price tag with it.

The damp can be water getting trapped behind your existing rendering. It only take a crack to let water in then it gets absorbed and travels. But if a bonding agent has been applied that is not breathable then your damp could be from within. Moist air condensing on cold walls.

I much prefer these old solid walls to have an ewi system in place. Waterproof, breathable (although to what extent) and keeps your heat in. What you will also need to put in place is some kind of all year round ventilation in place that works. I see so many homes that are sealed up creating moisture within with no way of it getting out. Then the tenant or owner moaning about black mould.

If you are the keep windows shut att all costs type then consider a product called Envirovent. Ideal for sealed up houses.

 

[yocky]

I'm pretty sure the damp is due to the poor/cracked render. You can see the cracks, and the damp is quite localised where the render is worst.

Wouldn't the bad render have to be hacked off anyway if I was having EWI? Or can you just install it over the old stuff even if cracked and loose?

 

[vfr12]

It can be installed over the old existing render. If is not in very bad shape,but by the sound of it should be ok.Saves you a lot of hassle .

 

[yocky]

So both plasterers have been round to look and I got a really good vibe from both of them, would happily employ either based on first impressions. The only problem is that although they both recommended K-rend as the best option, one said there was no need to hack off all the old render (just the unsound parts), the other guy said that would be madness and all of it would need to come off even though there would probably be significant work to be done repairing the brickwork before the new render could be applied.

How do I know who is right?

 

[Jgreenplastering]

Best practice would be to hack off but in the real world as long as existing is sound and solid it can be rendered over as long as they use the correct base coat and method


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[adapt]

I have seen a lot of plasterers these days rendering over the old stuff, I personally don't do external rendering as my area is mainly damp and timber treatments and renovations. What system is it they are using for this?
They are using big rolls of what looks like scrim ?
From what I can work out do they use a primer then apply a render and scrim scratch coat with beads then top coat?
I am only interested as the modern systems look a lot better to use than the old hack off and re-render in s&c