Rendering to the floor

[markwm]

In this picture:

http://www.wall2wallsolutions.co.uk/KarlsPics/KarlsPics2/11102007450.jpg
http://www.wall2wallsolutions.co.uk/SpecialistRender.htm

They seem to be using some kind of plastering bead to divide the two sections of renders. Anyone know what kind of bead you would use for this? and also is this a recommended solution? I assume it's to stop rising damp striking up the render.

 

[Nemesis]

We can also offer a colour matching service for the repairs of masonry and pointing
Our lime products and finishes are specially prepared for each individual property and will offer superior breathing properties, flexibility and long term protection from the elements
Do not confuse Hydraulic lime with Hydrated lime that is available from builders merchants this material will not set on its own and requires the addition of cement apart from plasticizing the mix this material does not have the same benefits as Hydraulic lime

The use of lime requires a high level of skill and knowledge. For more information on the benefits of lime render please visit our suppliers and for those of you who are looking into the possibilities of traditional lime finishes this is the best site to visit http://www.stastier.co.uk it supplies a large range of very high quality lime material.



This is what happens to a damp wall that has the incorrect mix of cement render.
As you can see the hard cement render has detached itself from the brick work and has caused some 'spalling'.
If the cement content is too strong it can cause damage to masonry, in effect it's like a cement "straight jacket"





To avoid descending damp the tops of the wall are also treated with a 'capping'

Self coloured Hydraulic lime


The fixing of stainless steel 'bell-casts'
Prior to application, any prepared areas must not be too dry as this prevents 'suction' of the top application

It is important for the finished appearance that the surfaces are level, flat and true The reveals are cleaned and 'trimmed' in Drip shields are added where applicable

Application in process


The application is still 'green' and starting to dry out and cure.

Below is a part completed renovation, as you can see the substrate had fallen into a bad state of disrepair (more text to follow for this article)











N.B. When the applied coats are drying they appear to be somewhat 'patchy', this is normal and is referred to as the 'Green stage'

Interesting...

Do not confuse Hydraulic lime with Hydrated lime that is available from builders merchants this material will not set on its own and requires the addition of cement apart from plasticizing the mix this material does not have the same benefits as Hydraulic lime

 

[Nemesis]

http://periodproperty.co.uk/forum/viewtopic.php?f=1&t=9337&p=106426#p106426

http://www.buildingconservation.com/articles/lime/hylime.html

 

[markwm]

Why are you quoting the whole page?

 

[Nemesis]

Why should I not?

St Astier only supplies hydraulic I believe. It's also not true that hydrate can only be mixed and used with cement.

Interesting, in light of other recent discussions. Not all on that page to be believed, IMHO.

(No idea about the bead. Presumably to do with their 'bell cast.)

 

[markwm]

ok, np. I didn't realise you were replying to other topics.

 

[Mark]

Do not confuse Hydraulic lime with Hydrated lime that is available from builders merchants this material will not set on its own and requires the addition of cement apart from plasticizing the mix this material does not have the same benefits as Hydraulic lime

Bugger!

Back in a minute - I've got some walls that must be about to fall down. Shame about the plaster as well....

 

[Nemesis]

We've got some lime gauged with cement (not by us... ) and it's crumbling like (another bad word)!

The Smeaton Project came to the conclusion it really isn't a good idea, in general.

Builders making cement mortars use hydrtaed lime in small quantities as a plasticizer, but (as long as it is fresh) hydrate can make acceptable non-hydraulic lime putty.

In conservation circles it's still a bit sniffed at, but I think in the main that's because of reliability problems in the past re the stuff not being fresh.

It's certainly better to use than cement, and in many places a darned sight easier to get hold of than any other sort of lime.

However - I suspect the beading in the pic is part of making the 'bell cast' or drip mould, to shed water and prevent it running to the base of the wall, which is often coloured a dark colour too to stop splashes from showing. In times past, the render was often cut off here and black paint used - I think maybe bitumen?

 

[markwm]

Wouldn't bitumen be a bad idea considering it wouldn't let vapour escape from the bricks at the bottom? it being basically a waterproof membrane.

 

[Gareth Hughes]

The Smeaton Project came to the conclusion it really isn't a good idea, in general.

The Smeaton Project final report was never published, but it came to the conclusion that if you're going to add cement to a lime mix, you'd be best off adding lots, or not adding it at all - the builders' traditional addition of a couple of trowelfuls "for luck" while the client and architect aren't looking is the worst case scenario.

 

[Nemesis]

It's possibly not a great idea, but something which was carried out in the past. I think maybe we are a little wiser about breathability now.

 

[Nemesis]

The above response was re bitumen.

Smeaton Project - I think is still ongoing!

Here's a little more from the past:


http://www.ihbc.org.uk/context_archive/54/overviewlimes_dir/overviewlimes_s3.htm

When I get a mo I will post a pic re why it's not a great idea to add cement to a lime mortar mix.