Traditional or Create vented gap repair?

[Penners]

Yes, green oak will probably move about a bit as it dries out. But if you've rendered with lime mortar, this is unlikely to be a problem. The mortar will flex a fair bit, and even if it cracks it's easy to patch because it heals itself.

As regards the render question, modern-method builders sometimes nod in the direction of a "lime mix" by bunging a shovel of lime powder in with the cement, to make the mortar a bit more plastic. Just ask the builders what mix they will use. If they mention the word "cement" then it's not a proper lime mortar, made with lime putty.

 

[MdB]

Re adding hydrated lime, please educate me so I can go back with query.

"added hydrated lime" suggests that it is a cement mix with lime. These mixes were apparantly popular a while back but shown to perform poorly. An external lime plaster should be lime and sand with maybe some hair, nothing else. Cement should not go anywhere near it.

 

[Nemesis]

And if a cement render, the addition of lime can make it fail prematurely.

 

[Lady_Mari]

The builder tells me he will be using the same render finish that is usual for modern timber framed houses. I don't know his reason for adding lime.

I thought this would be ok as was going by what Middi said in earlier post

"As the building is not listed the best thing you can do is to insulate between the studwork, use 9mm shuttering ply boards ( 1200 x 2400 mm) to satabilise the lateral movement, counterbatten with 50x25mm(tanalised) screwed onto the studs, breather felt on these finished with EML wire nailed on these.

Any combination of render can be used to finish
Use the cheapest option, it will probably match the rest of the render better. "

 

[Penners]

There's nothing wrong with Middi's recommendations, provided you're confident that you've got to the bottom of any damp problems, and eliminated them.

The suggestion to use more traditional methods allows for the possibility that damp will continue to be present in the wall - now or in the future - and allows the wall to breathe in order to ameliorate this situation.

Whichever repair method you decide to adopt, the most important thing is to ensure that the damp in the timber has thoroughly dried out before the wood is enclosed again, and steps are taken to try and prevent it for the future.

 

[Lady_Mari]

Penners,

Thank you for clarifying the situation.
We have decided to go with the traditional lime builder as the difference in price is not great enough to be tempted by the modern builder.
(In fact, we were surprised at the quote given).

The lime man will start on the internal in about 2 wks but is concerned that it is getting late in the year to risk doing the outside so we will hold off till the spring.

Meanwhile, could you or anyone give us advice concerning

"the bitumen coating on the brick upstand on outside walls is a bad idea as it prevents moisture escaping & forces it inside"

Looking around, all the older buildings appear to have black bases.

:?