Weather protection for masonry
25th July 2011
Bricks vary in porosity some bricks are soft and very porous such as common face bricks particularly modern LBC's (London Brick Company), whilst others are more dense and will repel/resist moisture to a greater extent such as; engineering bricks or blue damp course bricks designed to be used in exposed wet areas.
On most modern buildings you will find dense engineering bricks specified below and up to ground level, where a horizontal barrier (damp proof course) is installed to prevent wicking moisture from the ground (Rising Damp) affecting the upper structure. Dense engineering bricks are ideally suitable for these conditions, where contact with wet ground will usually have no damaging effect. Above damp proof course level bricks may change into a faceing brick which is usually aesthetically more pleasing, lighter and cheaper to use build with.
Older properties are commonly constructed from just one type of brick usually a face or common brick. Where damp proof courses have not been introduced either during construction or retrospectively bricks towards the lower level of the property can deteriorate when exposed to excessive dampness over a period of time. Bricks deteriorate or spawl when they become wet, during winter months trapped molecules of moisture freeze and expand shearing away the surface or face of the brick (spawling).
The source of dampness causing bricks to deteriorate may not just occur due to an absent or defective damp proof course, high ground levels, exposure to the elements and defective rainwater services or plumbing can also cause bricks to spawl. If you notice your brickwork spawling within a specific area this may indicate a localised problem probably one of the above. It is however, common to see random bricks spawling along a stretch of wall which is usually the result of a few weak/soft bricks deteriorating which were not fired (hardened) properly during the kilning process.
So how do you prevent brickwork from deteriorating?
If your brickwork is showing signs of deterioration you may well have a damp problem, establish the route cause of the problem rather than attending to any symptoms first, check internally to see if there are any signs of damage to the internal plaster, decorations or joinery, especially if your walls are of solid construction.
If you see any signs of damp internally instruct a professional surveyor to carry out an inspection and report. Contact the Property Care Association for help, the Property Care Association formerly part of the British Wood Preserving and Damp Proofing Association (BWPDA), is the leading trade body for damp proofing and wood preservation, in the UK. They have a list of trained and experienced professionals on their website who will be able to undertake an inspection and provide you with the necessary advice or repair service needed visit - www.property-care.org.
Carry out your own preliminary checks, Inspect ground levels externally, ensure if you have a damp proof course this is not bridged or its clearance to the ground not compromised by vegetation, soil or raised paths. The building regulations stipulate a minimum distance of 150mm (6" inches) should be maintained between the damp proof course and the external ground. If you find any of the above problems act, reduce ground levels as necessary and remove vegetation, plant growth and soil away from the walls.
Check your roof sufficiently overhangs your building, particularly if you have a gable elevation. Rainwater cascading down the external facade of your building can cause severe problems with damp, water ingress and spoiling brickwork. The roof and facia boards should provide weather protection to the building.
Inspect mortar pointing ensure mortar between the bricks/stonework is not weathered. Beware of certain styles of pointing such as strap pointing which can accelerate deterioration of weak brickwork and stone work by trapping water. Always ensure the mortar used for pointing is sympathetic to the construction materials.
Overhaul your gutters and rain water services, check these are not blocked by debris and all joints are sealed, you should also check the fall of the gutters to ensure they fall correctly to the down spouts/fall pipes.
Ensure any external over flow pipes from toilets, washing machines and boilers are not leaking.
How to repair Spawling brickwork?
If you only have a few random spawling bricks and no evidence of a severe damp problem it is likely these are weak and substandard bricks introduced during construction which can be simply cut out and replaced like for like. If you have larger areas of spawling brickwork it's likely to indicate an unaddressed issue, which a survey would identify. Always establish and attend to the initial problem first before undertaking any repairs.
If necessary and upon completing repair of the offending problem it is likely that brickwork may need to be removed and replaced if badly damaged or unsightly. This is specialist work as removing large areas of structural brickwork may compromise the integrity of the building and should only be undertaken by and experienced and trained professionals. When replacing brickwork in prone damp areas below ground or DPC level then specify a dense engineering brick or blue damp course brick to prevent the possibility of future spoiling.
StormDry is a deep penetrating masonry water repellent which can be applied to brick, stonework or concrete to protect against water ingress, moss, mould, algal growth and moisture damage. Once StormDry is applied it forms a breathable clear barrier which will not affect the colour or appearance of the masonry retaining its original look, reducing the porisity of the material and repelling water/moisuture.
Wet walls also have poor thermal properties allowing heat to escape through the wet construction. SafeGuards StormDry is scientifically proven to reduce heat loss in single skin masonry construction with an energy saving of up to 29%.
We have recently undertaken some large masonry repairs on a domestic property in York with severe damp problems which had caused significant damage to the brickwork around the ground floor walls. After attending to the inital causes of the problem the unsightly spawled brickwork was carefully removed in sections as to not affect the structure and replaced with new. Upon completion the walls were coated with Stormdry to provide additional protection against weathering to the existing and new brickwork reinstated.
If you have a problem with any of the issues mentioned in this article and your in need of professional advice or repair, please do not hesitate to contact us and see what we can do for you.
Russell Rafton C.S.R.T / I.S.S.E
Surveyor
Dryfix Preservation Ltd
01904 791388
