You may hear these claims being made by roof coating companies:
Claim 1) The Weight of Roof Moss Will Cause Structural Damage
This is complete rubbish and is an approach used by dodgy sales folk to scare the homeowner into using their roof cleaning services. Because the moss is spread over a wide area the weight is distributed evenly and is negligible. A roof will not suffer from structural failure due to moss growth.
There is absolutely no proof that moss causes structural damage.
Also bear in mind that the vast majority of roofs in the United Kingdom have moss growth on them, how many roofs have you seen collapse lately?
Claim 2) A Roof Coating Will Prevent Moss Growth on the Tiles
Moss killers and preventative treatments only work for a short period of time, after which the rain washes off the chemical and moss starts to regrow. Expect 2-4 years before regrowth, don’t expect too many roof coating companies to admit to that during the sales pitch!
Did you know you can buy a high strength moss killer (for roofs, paths, patios etc) on Amazon? Try this product.
You, or your local roofing contractor can even apply this chemical with a sprayer such as this.
Claim 3) Coatings/Sealants Will Increase the Value of the Property
This is utter rubbish, I know because I have asked 6 local estate agents. All agree that this product does not have an effect on the value of the property.
Of course, a roof covered in peeling paint may well put off a few buyers though:
Hot Tip: The best way to increase the value of a property is to update the kitchen, bathroom, boiler and windows, these are the key areas that buyers look at.
Claim 4) Save 40% on Heating Bills or Equal to 12 Inches of Loft Insulation
I have seen no evidence at all that this product will reduce heating bills.
Heat from the home is usually kept out of the loft by insulation placed above the ceiling, the loft itself is allowed to remain cool and ventilated, this prevents condensation. Adding a thin layer of paint/coating to the surface of the tiles will not improve the heat loss as any heat that does get into the loft can still escape through:
- Around chimney lead
- Around soil pipes that go through the tiles
- Overlaps/gaps in tiles (all tiles have small gaps and allow the loft to breath)
- Soffit or roof vents
It is perfectly normal and acceptable for a loft to be ventilated, it’s actually a regulation requirement on newly built homes. To reduce heat loss from the home, one should concentrate efforts on improving loft insulation, installing good quality “A” rated double glazed windows and checking seals around letterboxes and doors.
Claims of “25%” or even “40%” reductions in heating costs are absolutely absurd and unfounded. A roof coating product will not achieve this.
For further reading about magical dust applied to paints/coatings and other ludicrous claims made by some questionable manufacturers, please read this great article by Eco expert Martin Holladay.
The Florida Solar Energy Center as also states:
The Florida Solar Energy Center has tested ceramic paints and found them to have no significant advantage over ordinary paint in terms of their ability to retard heat gains through exterior building surfaces. These products are generally composed of elastometric coating products to which ceramic beads have been added. When tested side by side with the same elastrometric coating that doesn’t have ceramic beads, both products have virtually the same heat-gain retarding performance.
Claim 5) Waterproofs the Tiles
Tiles are waterproof anyway and will only leak if they break. Even old tiles remain waterproof until they break. Keeping water off the tile by way of a surface barrier such as a water repellent will only only work as long as the repellent remains on the tile. Most coatings/repellents I have seen tend to show significant wear & tear or even flaking between 3-6 years after application.
The gains achieved by this coating are easily offset by the high installation cost and relatively short life expectancy of the finished product.
Claim 6) Roof Will be as Good as New or Cheaper Than a New Roof
The roof will not look as good as new, it will look like a roof that has been covered in red/brown paint.
This approach would not fool a surveyor and after a few years the peeling/flaky paint could be an eyesore.
A new roof would not peel or flake like this.
Also, bear in mind that with a new roof you also get new felt, new nails/ fixings and new cement work.
As for claims such as “cheaper than a new roof” one must consider that these roof coatings are part of an ongoing process. Once applied they will need to be re-coated in the near future, usually after 3-10 years otherwise the roof will look awful.
Why pay £2500 every 3 – 10 years for a semi detached property when a whole new roof (inc felt, fixings, cement etc) will last 75 years+ and could cost only ~£5000?
Do the maths and you will find roof coatings are not cost effective. They might look great for a few years, but when they wash off it leaves the roof looking horribly patchy.