Cracks showing in walls of timber-framed house

Q My timber-framed house was built in 2005 and the supplier provided flexible steel wall ties. However, the builder said that these were not necessary and they were less convenient to use than the conventional L-shaped wall tie that he was familiar with. He didn't use the flexible ties provided by the manufacturer of the timber frame. There are now cracks appearing in the external plastered block walls. What is the best thing to do?

A The manufacturer of the timber frame will normally supply wall ties that are obtained from a supplier who can certify that the tie is designed for use with timber frames associated with an outer cladding of plastered blockwork or brickwork.

They are generally a flat stainless steel L-shaped tie where the shorter length is fixed to the timber frame with one fixing of the same material as the tie, or at least compatible with it. The spacing of the ties depends on the actual situation but it is typically fixed to the vertical frame studs to retain the outer wall at 600mm centres horizontally, 450mm vertically and 225mm vertically at openings.

Building standards state that wall ties should accommodate 6mm differential movement per storey with particular attention to be paid at openings. This is due to differential movement between the timber frame and outer masonry. Over a short period of time timber framework contracts while masonry expands.

The site installation should be in accordance with the timber frame manufacturer’s instructions; otherwise any warranty will be invalidated. It would appear that although your builder had good intentions he has departed from the manufacturer’s guidance.

If all components of such structures are properly designed and installed then a design life of at least 60 years can be achieved.

If the tie used has no flexibility then this may point to the cracking. However, there may be other factors involved. What is the size and pattern of the cracks and where are they located? Cracks generally occur around openings in the wall and may occur as a result of thermal expansion of the block and plaster which can be easily remedied. Other types of cracking vertically at corners and at random locations could suggest other factors.

However, all possibilities and not just the ties should be investigated and ruled out until you get to the root of the problem. This should entail forming an opening in the wall to reveal the concealed construction. In any event, I would advise that you seek assistance from a chartered building surveyor to investigate the cause and propose an appropriate remedy.

Jim Drew is a chartered building surveyor and member of the SCSI

Gutter replaced but wall remains damp

Q Approximately four months ago, I noticed I had a leaky gutter which resulted in the inside wall becoming wet and damp. Since then the gutter has been replaced, however the wall remains damp and is now infested with mould. Why is this?

Is there something else that I need to remedy this?

The wall is becoming quite unsightly and it is increasingly difficult to invite people to the house, which is particularly difficult for me as I run a business from my home.

A You don’t mention how your walls are constructed or how old the property is, so I will guess from your description of the problem that you have solid masonry walls, either stone, concrete or brickwork without a cavity. Water entering into walls over a period of time can begin to break down the mortar that binds the wall, particularly if it is lime mortar in an older property. Even after that water has dried out it may have caused salts to form in the masonry.

Often these salts can be “hygroscopic”. That means they attract water from the air to maintain a high water content within them. They periodically dry out towards the surface either by increased heat inside or during the summer on the outside. This then causes the “latent heat of evaporation” to cool the wall and more water is created by condensation on the now cold structure. Blistering of finishes or a white salty dust will often be noticeable and sometimes this is also accompanied by the growth of mould.

Hygroscopicity is a “self servo” process because the salts alternately liquefy with condensation, then crystallise as they dry out periodically and as the ambient conditions vary. Gradually, the problem will spread across the wall and the process is often mistaken as “rising damp” with expensive treatments proposed that seldom alleviate this type of problem.

The answer is to break the cycle by allowing complete drying out of the wall and treating the salts to prevent reoccurrence. Treating the mould problem alone might provide temporary alleviation of the aesthetic blemish but will not stop reoccurrence of the difficulty.

If you are now sure that no rainwater is entering from the outside, I would suggest localised removal of the plaster finishes, drenching with a chemical treatment such as Hey’di Antisulphat available from Sovereign Chemicals Ltd and replastering with a lime-rich renovating plaster such as Limelite from Pozament. Both are available online and a local tradesperson will be capable of following the instructions provided. After drying out, you should be able to redecorate without reoccurrence of the mould problem.

Generally such problems are caused in solid masonry or where cold bridging in cavities causes relatively cold surfaces allowing the formation of condensation upon which mould will thrive. A good long-term solution to such difficulties is the application of an external wall insulation system or EWIS. This will have the benefit of keeping the internal walls above the condensation temperature, lowering heating bills and improving comfort levels. Grants and further information is available from SEAI.ie. Fergus Merriman is a chartered building surveyor and a member of the SCSI’s Building Surveying Professional Group

Will shared access affect value of land?

Q I recently remortgaged some of my agricultural land and found out that the access to the land is shared with a neighbouring property on the deed maps. Will this have an impact on the value of the land?

A It is unlikely that the existence of a shared access route would have a serious effect on the value of the land, unless it has development potential. I take it that this is unlikely as the inference from your query is that the land has no road frontage and I am assuming a strictly rural location. Shared accesses are not unusual.

An alternative aspect that might affect value is if there is acrimony between the parties or a dispute as to the right of way which could cause ongoing problems, but I take it that this does not apply in this instance.

It would, in my opinion, be wise to establish your precise legal standing in relation to the laneway. You state that your neighbour has a right of way over the laneway. This infers that you are the owner of the laneway and that he has an easement over it. Are you certain that he is the lesser interest and not you?

You should confirm with your solicitor which one of you is the owner of the laneway and which one has the right of way only as this may have an effect on who is responsible for the maintenance of the laneway.

Find out if the right of way is registered against your property and if there is/was a written document in respect of same detailing the extent of use permitted for the right of way or any other pertinent matters.

Paul Good is a chartered rural surveyor and member of the SCSI Rural Agency Professional Group

Got a query? Send your queries to propertyquestions@irishtimes.com or to Property Clinic, The Irish Times, 24-28 Tara Street, Dublin 2. This column is a readers’ service. Advice given is general and individual advice should always be sought

Send your queries to propertyquestions@irishtimes.com or to Property Clinic, The Irish Times, 24-28 Tara Street, Dublin 2. This column is a readers’ service. Advice given is general and individual advice should always be sought