Rendering the Roundhouse using a traditional 'hot' lime mortar

17th May 2017

Tony and Phil rendering the Roundhouse using a traditional 'hot' lime mortar

Tony, Keith and Phil 'hot' lime render the west wall of the Roundhouse during last Sunday's community day drawing quite a crowd in to see the process of slaking produce some spectacular results.

Originally, we rendered the roundhouse with a traditional wattle and daub as would have been used for millennia. We then lime washed the walls to protect them from the elements.

The prevailing westerlies battered the walls all winter and took the lime wash off and began washing away the daub.

We then tried rendering the west walls with a lime render made with a dry hydrate lime, which is substantially harder than daub. And, again we lime washed over this. And, again the westerlies were too strong and the walls deteriorated once more.

You’ll notice that the beautiful walls facing the pond are still white and intact. These only have the original wattle and daub and lime wash and have now survived since 2013.

So, we are trying one final traditional building method, a much stronger hot lime mortar.

Hot-mixed lime mortars are prepared by adding specific measures of quicklime to aggregate and water and mixing together to form a mortar. The quicklime reacts with water generating heat, and simultaneously binds together with the sand or aggregate to produce a mortar. This mortar is ‘hot’ from the reaction and be used whilst still warm.

We hope this will finally solve the challenge of the West Wind!

Tony applies render to the west wall of the Roundhouse Tony and Phil begin the slaking process Tony and Keith mixing the mortar The render continues to slake whilst Tony applies renderThe lime begins to bubble as it is slaked with water Phil has added an improvised R.I.P. signs to the mound of lime aggregate