As wall ties corrode, bed joints widen and the outer leaf grows upwards causing tension in the inner leaf, therefore bending movement in the wall as a whole. Outward movement, or bulging, of the wall usually results with the inner leaf of the wall often being carried outwards as well as the wall ties which are normally intact to some degree at this stage.
Other common symptoms of wall tie failure include vertical and horizontal cracking, sagging of lintels, upward cambering of window sills, lifting of roof edges, separation of the window reveals and the separation of floors.
The corrosion of wall ties is due to several factors. Principal factors are:
Bricks vary considerably in their moisture absorption rate. Engineering bricks are almost impervious to moisture and water. Softer bricks however, behave like sponges.
Weak lime mortars are more porous than dense sand and cement mixes. The chemical action of mortars can vary between two extremes, either pacifying or encouraging corrosion. Ordinary Portland Cement mortars are alkaline in nature and as such discourage the corrosion of the wall tie. Other mortars will contain a proportion of sulphates which, when combined with moisture, creates a more aggressive condition than normal.
The location of any given elevation will determine the life expectancy of the wall tie, e.g. coastal, industrial or locations of persistent driving rain, are all vulnerable. The presence of salt within the atmosphere and coastal locations result in accelerated corrosion of wall ties. Industrial conditions will increase the acidity of the moisture reaching the ties, this can lead to a more aggressive and corrosive condition. Driving rain, by its very nature, increases the period at which the wall and its ties may be persistently wet. South and west facing elevations are more vulnerable than those on the north and east of the building. Poor design and construction problems including the lack of an effective damp proof course, blocked cavities, inadequate flashings and lack of cavity trays, are recognised as contributing factors to the ingress of moisture.
Tom & his team were brilliant from start to finish, they were all friendly, approachable, efficient & professional. At every point during the work Tom took the time to explain all aspects, give advice & realistic time frames, the end result was outstanding as was their work ethic of arriving when they said the would & always clearing up before they left. We would highly recommend Drysafe.
An extra big thank you to all the guys for ensuring our dogs stayed safe during the work by making sure the gates were always shut after use.
We approached Drysafe with a damp proofing requirement and they have been absolute stars from start to finish!
From initially meeting us at the property to explain what could be done, then overcoming changes in spec requirements with no drama no hassle what so ever !
Staying in constant contact, arranging a date to start and appearing on time, working flat out and finishing the job to a high spec, they arrived each, cleaned up each day and were a pleasure to have on site.
Thanks Guys really, really appreciated!
Tom and his colleague Orry were brilliant! Tom is knowledgeable, thorough in his assessment, super pleasant, amenable and professional. Whilst the work was noisy (nature of the job – damp proof course and membrane installation) Tom and Orry were efficient and clean. I would highly recommend Drysafe for quality of work, advice given and delivery of the end product. Thanks Guys, looking forward to a warm and dry winter!
Professional, knowledgeable, polite, tidy, did what they said they would do when they said they would do it. I cannot recommend Drysafe Construction more highly.
We were extremely grateful to Mike for giving up some of his Saturday to undertake the inspection and we found the recommendations incredibly helpful.
I’ve been really impressed with all that you guys have provided, especially Mike’s willingness to give us the extra advice whilst he was at the cottage…
Thank you very much for having a look at this property, I found the report very helpful and informative. If I come across any damp problems in the future I wouldn’t hesitate to contact you. Thank you very much for all your help
Thank you so much for an excellent service all-round, we will recommend you highly!
Thank you so much for getting back to us at such short notice and with such detail. We intend on doing something over the course of the coming months. It is so refreshing to meet a company that is local, approachable, customer orientated and easy to talk to!
Thank you for the report and the excellent service.
It was a pleasure to meet Mike and he did an awesome job.
Thank you for all your time and trouble over the last couple of years. I’ll be recommending you whenever the opportunity arises.
Thank you ever so much. I was very impressed with Mike and the service offered by your Company.