Property advice: Banishing blemishes

Removing stains from outdoor walls may need regular maintenance

To address leaching, proprietary solutions may have to be used.

Hi Brigid,

My brother was visiting me from the UK and he was hardly in the gate, literally, before he started picking up on a few shortcomings. While our front walls are fine, he noticed that the pillars either side of our front gate are streaky — stained black. They are capped with marble and I’m guessing the staining has come from these as the walls on either side of the pillars are generally fine. 

I gave the pillar a bit of a scrub but it didn’t make much impact, it’s totally ingrained. We are a corner house — built 20 years ago — so the low plastered wall is a very long curving one. Unless we can get a paint, which is a very good match with the rest of the walls — plaster grey — I’m guessing we’ll have to paint the whole thing. 

But will that work, or will the staining come through? Is there something else we should use?
Then he noticed that a red staining is coming through the side wall with our neighbours. What’s causing this and if we paint it will it come through the paint? Now all I can see are the stains. 

Then my daughter, who’s renting a small house with her boyfriend, told me they had seen an apartment for sale that they were interested in buying. The development is about 20 years old and while the apartment appears to be in good condition all I could see was the nasty red staining on the outside walls. 

It looks like the same red staining which is on our boundary wall. Is it the same thing? I don’t want to rain on their parade and they’re desperate to get their own place, but I’ve been reading up on ‘Celtic Tiger’ era apartments and the problems with them. What steps do you think they should take before taking this any further?
Gerry

Hi Gerry

Thanks for writing in. Isn’t it nice to know your brother cares as much about your property as you do. Let’s look at the staining issues first. Marble is a beautifully decorative material and a very attractive finish to gate piers. It’s also incredibly durable, with low porosity especially where it is polished. 

However, with the rain we get here, even marble has its work cut out for it, and will be forced to absorb some water. Water makes all stone susceptible, making its way into fissures and cracks and will undermine and wash out smaller stone chips and mineral deposits. In winter water can freeze and swell causing fissures to widen.

Unfortunately, and contrary to popular belief, or perhaps wishful thinking, maintenance has to be factored in.

Marble is also susceptible to environmental pollution. Acid rain, or even cleaning products containing highly acidic components, can break down the material, again causing leaching of mineral deposits. Over time a build-up of these mineral deposits may present as black streaks.

To address leaching, proprietary solutions may have to be used. I say solutions because there may have to be a combination of solutions to deal with the issue. It would be best to engage or seek advice from a cleaning company that specialises in the treatment of stonework. 

A stain-blocking solution may also need to be applied to prevent leaching into the future once the marble and the pier walls have been cleaned. Ensure, where possible, that cleaning solutions are environmentally friendly.

I will make the assumption that your reference to red staining at your property, and at the apartment your daughter is considering, is on external walls only. This is most likely red algae. Red algae is natural and seems to be largely present on Celtic Tiger properties. This is perhaps due to the development of new renders at the time. These were more absorptive than those developed previously.

The holding of water on wall faces is a lovely environment for the algae to grow in, and multiply and, as mentioned, when it comes to moisture, we aren’t in short supply.

The holding of water on wall faces is a lovely environment for the algae to grow in, and multiply and, as mentioned, when it comes to moisture, we aren’t in short supply. You will see it dominate the side of the building that gets the least sun, such as northern or eastern facades, or to all facades where topography gives greater shelter to the building.

Just like the marble issue above, an environmental proprietary cleaning solution is required. The building’s walls and chimneys can be doused in solution, a period of time must elapse to allow the solution to break down the algae and then the walls are cleaned with more solution. It is best not to power wash or to use abrasive tools because this may denude render texture (eg, Nap finish).

It is important to note however that all cleaning has to be done every five or six years or whatever the specialist cleaner advises. You will likely know when to get them back yourself because black streaking and red algae are so obvious. It simply has to become part of your maintenance schedule. Unfortunately, and contrary to popular belief, or perhaps wishful thinking, maintenance has to be factored in.

On your last query, the Celtic Tiger apartments, this is a very broad question but first things first. Have a chartered building surveyor carry out a building survey on the property and extend the brief to include compliance with building regulations and ideally have them do some opening up works.

Brigid Browne: 'May I wish you and all our readers a very happy St Brigid’s Day.'

The latter is not always possible, but it is perhaps the only way to get peace of mind. Recommendations for repair can be drawn up as part of the report and works can be carried out either by the vendor or by the purchaser (your daughter). A good solicitor will advise here. It would also be best to ensure the property has a management company in place. They act on behalf of the apartment owner.

So, a bit of a whistle stop solution to your queries Gerry, but I hope that some of it is useful.

Finally, and very importantly given the day that’s in it, may I wish you and all our readers a very happy St Brigid’s Day.

• Brigid Browne is a chartered building surveyor and chair of the Southern Region of the Society of Chartered Surveyors Ireland. She is the owner/ managing director of Cashel-based Fortress Planning which offers a range of services including assigned certifier, design certifier, building surveyor, and conservation consultancy to clients all over the country — www.fortressplanning.ie
• If you have a property related query or issue you would like to raise with Brigid, please email [e-mail]