Lime Render

[Murdo]

Hi Everyone, I am new to this site having just bought a 17/18 century farmhouse in Norfolk and never having owned a period property before. I have discovered that the previous owners have screwed a fence post to the corner of the building which has cracked the exterior render, which in turn is letting in moisture and causing damp in the corner of the internal room.

I am keen to make sure this doesn't get any worse and wonder if anybody can recommend a good builder experienced in lime render who can make the small repair. Or if it is the wrong time of year to make the repair how I can prevent more water getting in and making the damp worse.

Thanks

 

[88v8]

Hello and welcome.

Like so many things, you can easily fix it yourself. Don't be reaching for a builder every time some job wants doing, most of them are clueless where period houses are concerned and can cause considerable long-term damage. In fact, I would say never employ a builder to do anything until you've learned how to do it yourself, then you'll know whether they know what they're doing.

Anyway, your render... On a frost-free morning remove fence, rake/dust out loose material from crack. Make a mortar mix of one part Natural Hydraulic Lime to five parts sharp sand.
Wet the crack thoroughly by spraying it with a hand mister (the one you use for house-plants). Lime must be applied to a wet (not running, but wet) backing.
Firmly apply the mortar. Consolidate it after a couple of hours by tapping with a coconut brush.
If the render finish is rough, match it by rubbing with sacking when nearly dry, or the coconut brush.
Protect from freezing a couple of days.

Sharp sand from garden centre.
Lime - normally referred to on here as NHL - from here
http://www.ridgeons.co.uk/
Other suppliers are available.

Do not use the hydrated lime that any builders' merchant will sell you, it's not the same.

The lime will likely come in a fairly large bag. Store what's unused somewhere totally dry, and it will keep a long time.

Have fun.

Oh, and we love pictures... Photobucket...

Ivor

 

[Murdo]

Thanks ivor for such a comprehensive answer. Once this threat of freezing weather passes I will give it a go. When I do the repair should it be covered while drying and should I protect the crack until I can repair it.

 

[88v8]

If the crack is admitting water, then yes cover it if you can.

In the summer, the problem with lime is preventing it from drying too fast. Now, other than a downpour in the first 24 hours the only thing to worry about is frost - yes, some sacking covered over with plastic for a few days.

Ivor