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Restoring the walls of this old stone cottage with lime mortar

This project involved the removal of stone cladding, stone cleaning, lime pointing and lime render to an old stone solid wall house in the Oxfordshire area
The previous owners of this lovely Cotswold cottage decided to have the front wall re-faced in yellow reconstituted stone cladding by a firm called Everstone, (it also came with a reassuring 30-year guarantee!).
Situated near Banbury the cottage was built around 1830 in local iron stone, the cladding was added around 1983
Stone cladding and cement renders can cause damp:
The stone cladding that was glued onto the wall not only looked a little out of place, it was also causing damp.
The area under the downstairs front window was damp, also the cladding to the left-hand upper elevation under the guttering was holding moisture that for years had trickled behind the cladding from a defective roofline detail.
In the home information pack, the new owner (who purchased the house in 2018) found the original EverStone cladding brochure.

damp problems with stone cladding

Severe Damp areas circled

This stone cladding makeover brochure was given to the former homeowners way back in 1983 when they signed up to have their natural stone cottage cladded with coloured concrete.
The cladding installation for the front wall cost £2,800 that’s about £9,300 in today’s money (2019)
You can see the 1983 stone cladding Everstone brochure on the picture gallery below.

Despite some negative comments from general builders about removing the stone cladding, the new owner decided to investigate the possibility of having it removed. Some builders recommended painting the cladding, some rendering over the top of it and others said it would be impossible to remove without destroying the facade.

After some internet searches for stone, cladding render removal specialists the new property owner found our dedicated stone cladding removal site. 

BACK2BRICK.CO.UK   

 In order to provide some solutions a survey was arranged.

So what could be done to resurrect this lovely old stone cottage?

During the survey, we removed a small area of the stone cladding to inspect the original underlying natural stone surface. We recommended that the cladding and adhesive be removed. After removal of the stone cladding, we recommended that the real stone surface be acid wash cleaned and re-pointed in lime mortar. Due to the bottom section of the stone being eroded we specified that a small band of lime render be applied. Using local stone (some kindly donated by neighbours) badly spalled stones were replaced.

What’s the best render to use on solid wall houses?

We advise homeowners to be careful before covering up stone or brick with cement renders to cure damp or other problems, it may seem a strange idea to clad a real stone house with concrete cladding but an incompatible cement (concrete) render can be just as damaging.

We see lots of homeowners making the same mistake with concrete (cement) renders when trying to cure penetrating damp or just to give the walls a facelift,  both in brick and stone houses. A new concrete render applied as a solution to a wall problem may not look as ugly as stone cladding but its the same impervious material and can cause some serious damage by trapping moisture within the wall.

 

Solid wall houses of this period were often built on the ground with no damp proof membranes.  As such they have a higher moisture content within them.

The solid thick walls of older buildings were designed to absorb rain and then dry out. They were built with thick walls so that water ingress did not penetrate to the inside. The exterior surface of a wet wall soon dries out again in windy-warmer conditions.
Moisture within the wall is able to escape as the materials used in the build, namely the lime plasters and lime mortar along with the natural stone mean the house is able to breathe. Pointing, cladding or rendering old houses in cement-based mortars can seriously upset this balance and result in damp, with long term deterioration and damage to the fabric of the building.

The Lime Pointing mortar mix

Careful consideration is always given to the sand used for our lime mortars, after all, sand is the biggest ingredient of any mortar, it also has to be gauged accurately.

Natural Hydraulic lime was used (NHL 3.5). Locally sourced sand was used made up of three parts sharp sand and one part finer graded sharp sand. All mortar beds were cleaned and raked back 25mm

The benefits of using lime mortars are that they will breathe and flex. Lime pointing also looks right and in keeping with the natural stone. The pointing was bag rubbed flush to stone, this involved rubbing the mortar into the joints whilst it is still green (not fully set)

Shedding the cladding resulted in some serious weight loss for the cottage!

Stripping off the stone cladding resulted in the shedding of around 4 tonnes in weight.

Once again this period stone built cottage can breathe, the damp has been cured and we think you will agree with us that it looks a lot more like an old stone cottage.
If you would like more information on our restoration services for period solid wall houses brick or stone build, please.