Why do damp marks keep coming through?

Q Five years ago I renovated an old bungalow that included dry walling the interior wall on all the external walls. I am having issues with some of the walls since in that a damp mark from the holding nail (which is about 6cm in diameter) is showing through the plaster that was put on top of the dry wall. I believe they are called "mushroom holders". I have had to paint over the holes every 18 months or so to cover the mark.

I used stain-proof paint with wall paint over it. Have you any suggestions? I also got the outside of the external walls rendered.

A This sounds like an issue with condensation, leading to staining on wall surfaces. Air contains moisture. The temperature of the air determines how much moisture it can hold, and warm air contains more moisture than cold air.

When warm, moist air comes into contact with a cold surface the warm air is unable to retain the same amount of moisture as it did and the water is released onto the colder surface, causing condensation to form.

This dampness entraps dust particles from the air and can quickly lead to mould. Thermal bridging or cold bridging can happen when lower external temperatures are transferred to the inside of a building through a building material or component by a process known as conduction. The reduced temperature can lead to condensation on internal surfaces.

This is common in older poorly insulated properties such as the one you describe. Thermal bridging can promote dampness and lead to mould growth and staining.

In this case you have completed a renovation project and added insulation to the inside of the external walls and it is therefore disappointing that the problem of cold bridging remains.

The issue here appears to relate to a cold bridge between the other blockwork and the new inner plaster surface.

This bridge is formed by the metal core of the mushroom shaped fixings used to hold the dry lining in place. The metal core can easily transfer or conduct the colder external temperature to the inside.

As with any dampness issue, particularly the issue of condensation, improvement in both heating and ventilation levels can help and should be your first port of call.

You mention that the problem appears to persist on just some of the walls. I suspect that these walls are the colder north- facing ones, or walls in less used rooms where issues of dampness and mould can be more prevalent.

The use of some brush applied treatments can in fact make the issue worse as the building fabric can lose breathability, meaning moisture can become trapped in the structure.

The use of good quality paints can help in some cases. My advice would be to carefully clean and sterilise any staining to reduce the likelihood of regrowth of mould and then repaint.

In tandem with this you should improve ventilation and heating and then monitor the situation. I would be hopeful that these simple steps should improve your situation. If the problem returns it would be worthwhile having the issue looked at by a building surveyor as dampness issues can be tricky to diagnose without site specific investigation.

Noel Larkin is a member of the Society of Chartered Surveyors Ireland (SCSI) Building Surveying Professional Group

My kitchen is cold

Q My kitchen is an addition to my house and is 14ft x 8ft (4.2m x 2.4m). Recently I extended my kitchen units to accommodate an eye-level fridge and had to change the radiator which was there. I now have one of the more modern ones 36" x 20" and was assured that it would be sufficient to heat the room.

This is not the case. When I have the central heating on the rest of my house is very warm but not the kitchen, which takes ages to heat. I had a new boiler installed last year which is very efficient but, despite being told that the radiator would be perfectly fine, this is not the case. I have made many enquiries but have got no help.

All I am told is that this size radiator is the proper size. I got an estimate to have the roof, which is flat, insulated, but it would cost €3,000.

The walls in the house have been insulated. The house is a three-bedroom semi-detached and is a warm house otherwise. Before I changed the radiator the old one was perfect – except now I do not have room to put in a wider one. Can you help?

AGiven the description of the extension and the radiator it would seem on the face of it that the radiator is an adequate size to heat the kitchen area. A room of this size would require about 1kW of heat output to achieve a comfortable level of heating. Therefore it would be best to focus on the performance and siting of the radiator.

If the radiator is at the end of a long leg of piping this could result in significant heat loss in the radiator. You could also check for air locks within the radiator itself. You could also check your boiler settings with regards to the water temperature it is circulating.

Radiators as their name suggest ‘radiate’ heat via the air flow around them. The positioning of radiators within rooms dictates to a great degree how efficiently they will heat the space. Traditionally radiators were positioned under windows with no obstructions to restrict the free flow of air over and through them.

In summary, check for air locks in the radiator, ensure that your boiler is adequately heating the water flowing to the radiators, insulate long dead legs of piping and if all else fails look at re-positioning your radiator to get a more efficient distribution of heat.

Peter Duignan is a member of the Society of Chartered Surveyors Ireland (SCSI) Building Surveying and Project Management Surveying Professional Groups

Invest in property

Q I have money on deposit earning next to nothing. I have seen some of the returns on investment property from auctions and at these returns, I would really like to get involved.

The problem is, I know little about property investments but I do understand the property market and I feel the investment property market now offers me the best chance of a decent return along with the possibility of me buying at the "bottom of the market" (I know I have missed the tax-free seven-year CGT which expired in December).

I don’t want to buy a house as I don’t think the returns would be as good. On top of the purchase price, what would be any additional costs involved in buying an investment property and is there anything that I should be aware of?

AYou allude to possibly acquiring at the “bottom of the market”. I am afraid that boat has sailed and already some parties who have acquired within the last 12 months are now cashing in their chips to take a profit. That does not imply that there is no value in the market. You refer to “a decent return”; this can be determined by a quick turnaround or over a medium to long term, depending again on the individual requirements.

Some questions arise. What budget do you have? This may include or exclude certain sections of the market and would determine the level and type of competition.

Is the investment to be made on an individual basis or by a company or trust? This throws up queries on tax issues.

You indicate that you require an income stream, however, the level of risk or security required needs clarity. It would be necessary to identify whether a single occupancy tenant is required or whether there is an appetite for a multi-tenant investment which may require a greater management role.

There are three main commercial investment property sectors: offices, retail and industrial. Each sector has its own characteristics and market conditions. There is currently a shortage of prime office space due to the time lag for delivering new products. This has resulted in rental and capital appreciation.

There are also issues with obsolete buildings which cannot comply with modern regulations.

This is a simplistic overview and further analysis of which sector would provide the best return for you depends on your specific requirements. I would strongly advise you to seek professional advice before proceeding.

Mervyn Feeley is a member of the Society of Chartered Surveyors Ireland (SCSI) Commercial Agency Professional Group

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