Preparing Your House for Exterior Painting: Should You Clean It First?
If the exterior of your home is looking tired, stained or discoloured, repainting can seem like the obvious solution.
But before arranging exterior painting, it is worth finding out what condition the surface underneath is actually in.
Algae, mould, lichen and other organic growth can gradually change the appearance of painted render and masonry, particularly on shaded or weather-exposed elevations. What looks like faded or tired paint may, at least in part, be contamination sitting on the surface.
Professional cleaning and biocide treatment can reveal a very different surface underneath. In some cases, homeowners may find that the existing finish is still in better condition than expected, meaning repainting can be postponed or may not yet be necessary.
Before you repaint, find out what you're actually looking at.
Why Clean Exterior Walls Before Painting?
Exterior paint performs best when it is applied to a clean, stable and properly prepared surface.
If algae, mould, dirt or other contamination is left in place, the new coating may be going over material that should have been removed or treated first. That can affect both the appearance of the finished job and how well the paint adheres over time.
The right preparation depends on the surface and its condition. In some cases, this may involve biocide treatment to deal with organic growth, followed by appropriate cleaning and sufficient drying time before any painting begins.
At CleanSafe, we do not assume that every exterior wall should simply be pressure washed. Painted render, older coatings and some masonry surfaces can be damaged by overly aggressive cleaning.
The aim is to prepare the surface properly while protecting the material underneath.
And there is another reason to clean first:
You get to see the true condition of the existing finish before deciding whether repainting is actually necessary.
Is It Faded Paint, or Is the House Simply Dirty?
This is one of the most important questions to answer before committing to exterior painting.
Over time, exterior walls can become covered with atmospheric dirt and organic growth. Green algae is usually easy to recognise, but other contamination can create darker staining, patchiness and general discolouration that makes an otherwise sound painted surface look older and more faded than it really is.
This is particularly common on elevations that receive less sunlight, stay damp for longer or are affected by nearby trees, vegetation and prevailing weather.
Until that contamination has been treated, it can be difficult to judge the true colour and condition of the finish underneath.
That is why a sensible approach is:
Treat. Clean. Assess. Then decide whether to paint.
If the existing coating is still sound, cleaning and biocide treatment may reveal that the surface is in considerably better condition than expected.
If the paint is genuinely faded, peeling, chalking or otherwise deteriorated, that becomes much easier to assess once the contamination has been removed.
You May Find You Don’t Need to Paint
One of the benefits of treating and cleaning exterior walls before committing to repainting is that you can make that decision based on the condition of the surface itself, rather than the contamination covering it.
Where the existing paint or render finish is still sound, much of the tired or discoloured appearance may be caused by algae, mould, lichen and other organic growth.
An appropriate biocide treatment targets this organic contamination. Depending on the treatment and the level of growth present, the improvement may continue to develop over the following weeks and months as dead organic matter breaks down and is gradually weathered away.
Biocide does not repaint a surface, restore lost pigment or repair a failed coating. But where organic growth is the main problem, the improvement can be significant.
Once the walls have been treated and given time to clean down, you can properly reassess the exterior.
You may find that the existing finish is still in good condition and that repainting can be postponed, or may not yet be necessary.
If the paint genuinely is faded, peeling, chalking or deteriorated, you will know that painting is still required, and the preparation work has already begun.
Either way, it makes sense to find out what condition the surface is in before paying to cover it with another coat of paint.
Illustrative example: treating and cleaning organic growth can reveal a much cleaner existing finish without repainting.
What About the Roof?
If you are considering repainting your house as part of an exterior refresh, it is worth looking at the roof at the same time.
A roof affected by moss, algae and lichen can make the entire property appear older and more weathered, even when the walls themselves are still in reasonable condition.
Depending on the roof type, condition and level of growth, professional treatment may involve removing heavier moss before applying an appropriate biocide to treat the remaining organic contamination.
As with exterior walls, biocide treatment is not necessarily an instant cosmetic process. The treatment continues to work after application, with remaining organic growth gradually dying back and weathering away over time.
Treating both the roof and exterior walls can therefore significantly improve the overall appearance of a property, particularly where organic growth is responsible for much of the discolouration.
Once both have had time to respond to treatment, the house can look very different.
At that point, it makes sense to look at the property again before making the final decision to repaint.
You may still decide that painting is needed. But you will be making that decision based on the condition of a clean property, rather than one whose appearance is being affected by years of organic growth.
Why Not Just Pressure Wash the Walls Before Painting?
Pressure washing can be useful on suitable exterior surfaces, but it is not automatically the best way to prepare every house for painting.
Painted render, older coatings and some masonry finishes can be vulnerable to excessive pressure. An overly aggressive approach can damage the existing finish, mark render, loosen weak material or force water into cracks and other vulnerable areas.
More importantly, simply removing the visible surface growth does not necessarily deal with the biological contamination responsible for it.
Where algae, mould, lichen or other organic growth is present, an appropriate biocide treatment can target that contamination rather than relying solely on mechanical force to remove what can be seen.
At CleanSafe, the cleaning method is selected according to the surface, its condition and the type of contamination present. Depending on the property, this may involve biocide or softwash treatment, controlled rinsing or other appropriate cleaning methods.
The objective is not to use as much pressure as possible.
It is to achieve the required result using a method appropriate to the surface being treated.
How Long Before Painting Should the House Be Treated?
If you are planning to have your house painted, exterior cleaning and treatment should ideally be considered well before the painter is due to begin.
Biocide treatments are designed to continue working after application. Organic growth such as algae, mould and lichen is treated and gradually breaks down, with natural weathering helping to clean the surface over time.
How quickly this happens will vary depending on the surface, the type and extent of contamination, weather conditions and the treatment used.
For that reason, it can be beneficial to treat the property sufficiently in advance of the proposed painting work rather than viewing cleaning simply as a last-minute preparation job.
This gives the treatment time to work and, importantly, gives you an opportunity to see the true condition of the exterior once the organic contamination has cleared.
You can then make a much better-informed decision:
Does the house genuinely need repainting, or did it mainly need cleaning?
If painting is still required, the cleaned surface can then be assessed by your painting contractor for any additional preparation, repairs, priming or coating requirements before painting begins.
CleanSafe can advise on the likely treatment process and expected timescale after assessing the property.
Don’t Forget Gutters, Fascias, Soffits and uPVC
If you are refreshing the exterior of your home, the surrounding details can make a significant difference to the finished appearance.
Gutters, fascias, soffits and downpipes gradually accumulate atmospheric dirt, algae and staining. Exterior uPVC window and door frames can suffer from the same problem.
These areas may not seem particularly dirty when the roof and walls are affected by organic growth, but they can become much more noticeable once the larger surfaces have been treated and cleaned.
Cleaning them as part of the overall exterior preparation can give the property a much more complete and consistent appearance.
There is also a practical advantage to doing this before any painting takes place. Cleaning gutters, fascias, soffits and uPVC afterwards can result in dirty water and debris running over newly painted surfaces.
For homeowners considering a complete exterior refresh, it makes sense to look at the property as a whole:
Roof, walls, gutters, fascias, soffits, downpipes, windows and doors.
You may be surprised by how different the house looks when the exterior is properly cleaned, before a paint tin has even been opened.
A Sensible Order for Preparing Your House for Painting
If you are considering repainting your home, it can be tempting to start by choosing colours and contacting a painter.
A better approach is to first establish what condition the exterior is actually in.
A sensible sequence is:
Inspect the property and identify organic growth, staining, deteriorated coatings and any areas that may require repair.
Assess the roof for moss, algae and lichen, and determine whether cleaning or treatment would improve its condition and appearance.
Treat the exterior walls and roof as appropriate, using methods suited to the surfaces and the type of contamination present.
Clean gutters, fascias, soffits, downpipes and exterior uPVC, including window and door frames where required.
Allow the treatment sufficient time to work. Biocide treatment can continue to improve the appearance of treated surfaces as dead organic matter gradually breaks down and weathers away.
Reassess the property once it is clean. Look again at the condition and appearance of the existing paint or render before deciding what needs to happen next.
Carry out repairs and painting if they are still required. If the existing finish has genuinely deteriorated, you can proceed knowing that the property has been properly cleaned and assessed beforehand.
The important step is number six.
Don't automatically assume that a tired-looking exterior needs another coat of paint. Find out what it looks like when it is clean first.
Planning to Paint Your House? Talk to Us First
If the exterior of your home is looking tired, green or discoloured, don't assume that repainting is necessarily the first step.
CleanSafe can assess the exterior and recommend an appropriate cleaning or treatment process for the roof, walls and surrounding exterior surfaces.
If painting is still required afterwards, you will have a cleaner property and a much clearer picture of the condition of the surfaces that need to be prepared and painted.
But if much of the tired appearance was being caused by algae, mould, lichen and other organic growth, you may find that the existing finish is in better condition than you thought.
That could mean repainting can be postponed or may not yet be necessary.
We provide professional exterior cleaning and treatment throughout Sligo, Leitrim and Donegal, including roof cleaning and moss removal, exterior wall and render cleaning, biocide treatment, and cleaning of gutters, fascias, soffits, downpipes and exterior uPVC.
Thinking about painting your house? Let us help you find out what it looks like clean first.
