Lime putty, lime mortars, lime plasters and limewash at unbeatable prices are some of the traditional and ecological building conservation products supplied by Mike Wye & Associates, Rebuilding

Lime putty mortars offer advantages over cement based mortars for external rendering, especially when decorated with a traditional limewash:

their porosity allows the structure to "breathe"
they can accommodate general movement better
their self-healing nature reduces cracking problems

As with all lime based materials the best outcome requires patience and careful control of drying and suction, the reward being a good looking and long lasting render.

Any existing render must be removed, except any sound lime mortars. Care must obviously be taken to ensure that the structure is not damaged. Look out for very thick patches of render that are effectively load bearing. It may be necessary to render on top rather than risk rebuilding an area.

It is very important to control suction from the background material (substrate) by wetting before applying each coat (especially cob and porous brick) and in warm weather it will be necessary to spray each coat with water afterwards and cover with hessian to slow down drying.

dub out any deep holes in the wall with a haired lime putty mortar, rebuilding defects with cob blocks, cob bricks or stone.
treat wooden lintels with preservative and counter batten with oak lath.
apply one hand harled coat of lime putty mortar to provide a key to cob, with stone this is a matter of preference depending on the friability and size of stone/joint.
apply sufficient coats of haired lime putty mortar to smooth the contours of the wall
apply a top coat of floated or hand harled lime putty mortar as desired
protect all coats from the weather during and after application with hessian sheets to improve curing. As with any external render don't apply in temperatures below 5oC or if there's a risk of frost.

We suggest a 3.5/1 mix of coarse well graded sand to mature lime putty where a pozzolan is to be added. Lime renders gain strength by carbonation with carbon dioxide from the air. In damp, frost prone or very exposed situations it may be appropriate to add an extra ingredient to a lime render to increase its compressive strength and frost resistance. Traditionally volcanic ash or brick dust were added, these are forms of burnt clay called pozzolans after the Italian town of Pozzuoli where volcanic ash was used by the Romans. We use a calcined clay from Cornwall called metastar at a volume gauge of 10 -25% depending on degree of exposure. It's only added when knocking up the mortar just prior to use. It won't give an overnight set but will slowly begin to add a little extra compressive strength to the mortar after a couple of weeks.

For the example specification above, per square metre:

1 scat coat of 0.3mm - 0.3 tubs of 3.5/1 unhaired mortar - 21kg size
2 dub coats each of 12mm - 2.4 tubs of 3.5/1 haired mortar - 21kg size
1 floated top coat of 10mm - 1.0 tub of 3.5/1 unhaired mortar - 21kg size

Limes are caustic. Always wear eye protection and protective gloves and clothing and follow the safety instructions on the labels.

Our advice and information are given in good faith. It's important that users satisfy themselves that they've chosen an appropriate product and have a suitably skilled workforce.

Mike Wye & Associates Suppliers of Traditional and Ecological Building Products Phone us on 0044-1409-281644 or e-mail us by clicking on sales@heritagelime.com						Please click below for: Home Lime Products Repair Guidesheets Photo Gallery Limewash Colour Chart About Us
Guidesheets: Rendering
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Rebuilding	Plastering	Pointing	Limewashing	Metastar	Cob
Lime putty mortars offer advantages over cement based mortars for external rendering, especially when decorated with a traditional limewash: their porosity allows the structure to "breathe" they can accommodate general movement better their self-healing nature reduces cracking problems As with all lime based materials the best outcome requires patience and careful control of drying and suction, the reward being a good looking and long lasting render. Preparation: Any existing render must be removed, except any sound lime mortars. Care must obviously be taken to ensure that the structure is not damaged. Look out for very thick patches of render that are effectively load bearing. It may be necessary to render on top rather than risk rebuilding an area. Damping: It is very important to control suction from the background material (substrate) by wetting before applying each coat (especially cob and porous brick) and in warm weather it will be necessary to spray each coat with water afterwards and cover with hessian to slow down drying. Example Specification: dub out any deep holes in the wall with a haired lime putty mortar, rebuilding defects with cob blocks, cob bricks or stone. treat wooden lintels with preservative and counter batten with oak lath. apply one hand harled coat of lime putty mortar to provide a key to cob, with stone this is a matter of preference depending on the friability and size of stone/joint. apply sufficient coats of haired lime putty mortar to smooth the contours of the wall apply a top coat of floated or hand harled lime putty mortar as desired protect all coats from the weather during and after application with hessian sheets to improve curing. As with any external render don't apply in temperatures below 5oC or if there's a risk of frost. Gauging: We suggest a 3.5/1 mix of coarse well graded sand to mature lime putty where a pozzolan is to be added. Lime renders gain strength by carbonation with carbon dioxide from the air. In damp, frost prone or very exposed situations it may be appropriate to add an extra ingredient to a lime render to increase its compressive strength and frost resistance. Traditionally volcanic ash or brick dust were added, these are forms of burnt clay called pozzolans after the Italian town of Pozzuoli where volcanic ash was used by the Romans. We use a calcined clay from Cornwall called metastar at a volume gauge of 10 -25% depending on degree of exposure. It's only added when knocking up the mortar just prior to use. It won't give an overnight set but will slowly begin to add a little extra compressive strength to the mortar after a couple of weeks. Quantities: For the example specification above, per square metre: 1 scat coat of 0.3mm - 0.3 tubs of 3.5/1 unhaired mortar - 21kg size 2 dub coats each of 12mm - 2.4 tubs of 3.5/1 haired mortar - 21kg size 1 floated top coat of 10mm - 1.0 tub of 3.5/1 unhaired mortar - 21kg size Safety: Limes are caustic. Always wear eye protection and protective gloves and clothing and follow the safety instructions on the labels. Our advice and information are given in good faith. It's important that users satisfy themselves that they've chosen an appropriate product and have a suitably skilled workforce. BACK TO THE TOP