David Pope, of Windsor-based brick specialist Ernest Barnes, answers some common questions about brickwork and render and the best methods of repair or replacement.
QA section of render has fallen off the wall and the surrounding area sounds hollow when tapped; should all the render be removed?
Minimum intervention is generally best with pockets of detached or hollow-sounding render repaired in isolation. Removing large areas that are sound is not cost-effective, can cause potential damage to the fabric of the building and may seriously affect its architectural character.
QWhat should be done about brickwork that is covered by a hard cement render as there are signs of damp inside the house?
Moisture is probably becoming trapped between the render and the surface of the brick, and is therefore working its way through to the internal surface. Ideally, the cement render should be carefully removed using hand tools or a small masonry drill with a hammer or demolition setting. Severely damaged bricks should be replaced and bedded in lime mortar. The wall should then be lime rendered.
QWhat should be considered when rendering an old house?
The location of the property, its orientation and exposure to the elements all inform the specification of a new lime render. Work should usually be undertaken between April and October to avoid the frost season and prevent damage or failure of the lime. Lime renders should only be painted with a limewash or breathable paint, never with modern paints.
QShould any cement rich pointing be removed from brickwork?
Only remove pointing if absolutely necessary; for example where it’s causing dampness internally or failure of the surrounding bricks. Removing cement pointing is potentially very difficult and can cause damage to the brickwork. If there is no alternative and the pointing has to be removed, engage a specialist company to do so.
QHow can old pointing best be removed? Existing worn lime pointing can often be raked out with a nail fixed to a piece of wood. Tougher material should be removed with tungsten-tipped chisels that are smaller than the width of the joint. Tough cement pointing will need to be drilled down the centre of the joint with a small drill bit. The remaining mortar can then be removed using small hand tools. Never use mechanical grinders as they can cause irreparable damage to brickwork.
QIs it possible to repair or replace damaged bricks? Sometimes individual bricks can be carefully cut out and, if the rear of the brick is of sound quality, reversed. If the brick is not salvageable, a new brick may be re-bedded in its place.
QHow can dirt and paint be removed from external brickwork?
Great care must be taken to avoid damaging the surface – fire skin – of the original brickwork. In some cases, a poultice can be brushed on, which then forms a rubber-like consistency that can be peeled off, pulling the paint with it. Another method is for a certified contractor to use a special machine that generates a jet of steam. With any method, test a small area first. Never grit blast brickwork as this causes severe damage.
– handmade bricks.
Tel: 01787 269232; bulmerbrickandtile.co.uk – brick and flint specialist.
Tel: 01753 833533; ernestbarnesltd.co.uk – traditional brick manufacturer. Tel: 01229 462411; furnessbrick.com
– supplies a range of brick types and lime mortar. Tel: 01403 785141; lambsbricks.com – specialist lime products. Tel: 01409 281644; mikewye.co.uk
– specialist brick cleaning services. Tel: 01453 540600; stonehealth.com
– paint strip products. Tel: 01787 371524; stripperspaintremovers.com – range of lime materials. Tel: 01874 611350; lime.org.uk
– lime supplies and specialist advice. Tel: 01924 400651; womersleys.co.uk