Choosing type of lath for re-rendering

[Hatster]

Hi folks, I'm back after a long hiatus and looking for advice again.

We're planning to re-render the outside of our 17th century timber-framed house in lime plaster in the spring. I've had quotes for using sawn larch lathing and riven chestnut lathing, with a substantial difference in price. Is the quality of the riven chestnut that much better that we should pay the extra £4,500 ?

I'm also keen to include some sheeps wool insulation - any disadvantages to this that people know of? I fantasise about the house being covered in a snuggly woolen jumper.

And of course, we then need to decorate the outside. One of the plasterers suggested that rather than using limewash, we might want to use a longer lasting type of 'paint', but I can't remember what it was called. Do people have any ideas / advice on this?

Thanks very much!

 

[JoceAndChris]

Hi Hatster and welcome back. Been a long time - what'cha been up to?

No personal experience of doing what you're contemplating, but certainly our chestnut guttering, which cost the previous owner a small fortune back in the 80s, is going strong, so it must be good wood.

You might find this thread interesting, on the subject of paint:

http://www.periodproperty.co.uk/forum/viewtopic.php?f=1&t=12448&p=165797#p165797

 

[Penners]

Welcome back, Hatster

Riven chestnut laths will be stronger than sawn larch - sawing cuts through the fibres of the wood, whereas splitting follows the fibres. Chestnut is also a more expensive timber than larch, particularly at the moment*. However, I imagine you can do far more good for your house by spending that £4500 elsewhere in the building, rather than on the more expensive laths. So - speaking for myself - I'd go for the sawn larch.


* A lot of larch is coming on to the market because the larch is suffering from a fatal disease, Phytophthora ramorum, which is very worrying. However, the timber is permitted to be sold, provided certain biosecurity measures have been taken.

 

[Pford75]

On the subject of exterior decorating, we recently completed the stripping and lime washing of our home.

I would firstly say that the aesthetic effect of limewash is far superior (IMO) to any paint. It's also much nicer to apply. We did think about the lifespan of the product, so we went for Corical Lime (Telling Lime can supply). This is limewash mixed with crushed marble dust and supposedly lasts in excess of 10 years. I was sceptical, so I took up a couple of NT references from my decorator and they too raved about it.

 

[dans]

On the subject of exterior decorating, we recently completed the stripping and lime washing of our home.

I would firstly say that the aesthetic effect of limewash is far superior (IMO) to any paint. It's also much nicer to apply. We did think about the lifespan of the product, so we went for Corical Lime (Telling Lime can supply). This is limewash mixed with crushed marble dust and supposedly lasts in excess of 10 years. I was sceptical, so I took up a couple of NT references from my decorator and they too raved about it.

Any pics??

 

[Pford75]

I'm overseas on business at the moment, but here are the couple of pics I have on my laptop. Not the best view, Flyfisher has also seen the house 'in the flesh'. The subtleties of limewash are best appreciated when it rains as well.

This is during the paint stripping -

This is after the limewash (apologies for the fridge in the foreground awaiting collection!)

 

[Penners]

Wow! If that doesn't sell gallons of that finish, nothing will!

Pford75 - what are the two offset vertical white lines behind the left-hand ground-floor window? Are they something to do with secondary glazing?

 

[Pford75]

There are two metal brackets mounted on the wall exterior which can be used to 'retain' the secondary glazing. That corner of the house is older than the rest (you can see the flint which remains from a previous building on the site). The windows have a sash (as with the other windows) which you can see internally, but then with two external secondary full length windows which open outwards. To be honest, we never really open them, but they are an interesting feature. Well spotted....your eyesight is obviously very good. :wink:

 

[dans]

Fantastic! Thanks for sharing!

 

[MatthewC]

I'm also keen to include some sheeps wool insulation - any disadvantages to this that people know of? I fantasise about the house being covered in a snuggly woolen jumper.

I used Thermafleece sheep's wool in my loft - it's great to use, and the only issue is the cost. Offhand, I cannot be sure if you can use it vertically in walls. See the Mike Wye website (other websites are available!).

NB I'm surprised that your riven chestnut lath would be quite so expensive - do you have a really huge area to cover?

 

[skier-hughes]

you can buy the wool in block form for vertical use.

 

[Flyfisher]

I'm overseas on business at the moment, but here are the couple of pics I have on my laptop. Not the best view, Flyfisher has also seen the house 'in the flesh'.

Yes, it's a lovely job. One thing Pford75 didn't mention was the use of a 'slurry coat' (I think that's the term) that was applied before the final corical lime coating. This was used to 'even out' some of the rougher texture of the walls but without obscuring the underlying construction, particularly the flint parts. I have a similar situation (and quite a few cracks!) with some of our walls, hence my interest.

And of course, we then need to decorate the outside. One of the plasterers suggested that rather than using limewash, we might want to use a longer lasting type of 'paint', but I can't remember what it was called. Do people have any ideas / advice on this?

Your plasterer may have been thinking of silicate paint. Have a look on the web, there's a lot of information about it. It's suitable as a limewash substitute for traditional buildings but is far longer-lasting at around 20 years or so - though it is very expensive.

However, the cost of such things is more than just the material cost. If scaffolding is required, for example, then limewashing every 3-4 years can be a very expensive undertaking compared with using a silicate paint every 20-25 years. As ever, individual project circumstances will differ. The good thing is that there is quite a range of technically suitable 'paints' to choose from these days in terms of cost and longevity, so there's little excuse for using inappropriate coatings.