Do sprayed external wall coatings really last 20 years?

a painter and decorator with van

This article is an answer to a really good question posed by a user of our website…….

I have a quick question regarding your wall coating.

What is the  process for re-applying the protective wall coating after 25 years?

Does it  need to be stripped and re-applied, or can a new coating be simply laid over the  old? I would value your advice as we are hoping to get this work re-done after Christmas.

Mr. T, from Stafford.

Hi, thank you ever so much for your email, it’s always nice to hear from users of the website who talk with such enthusiasm about their houses.

No 2 jobs are ever the same

It is very difficult for me to comment on a coating on a certain house as each job presents its own challenges and each house is different (one reason why exterior wall coating companies such as ours rarely have an “average” price list as no two houses are ever the same), however one thing is for sure, i am pleased to hear that you had a coating that has lasted for 25 years.

If I may, I would like to post this question on our blog to encourage other users to read and respond, although it would be posted anonymously, if that is ok with you?

Installation must be perfect

In some cases, when the installation of the coating was conducted in a textbook fashion in perfect weather conditions with excellent quality coating materials and using a Graco president airless spray machine connected to a twin or single tool diesel compressor, then yes there is no reason why it cannot last for 25 years.

GRACO PRESIDENT TEXTURED WALL COATINGS SPRAY PUMP

A graco president spray machine

In fact I myself have surveyed houses that have had a textured coating over 35 years ago (!), and was applied in the 1970’s by Kenitex,  however admittedly it was waaaaaay past its sell by date, but (most of) the all coating was actually still on the house.

Be wary of exterior wall covering adverts that promise a 25 or 30 year warranty as it is unlikely the company will be around to honour it if anything goes wrong. That sort of guarantee is purely sales focussed as the typical lifespan is between 15 and 20 years in reality.

In that case, usually the best method is total removal and start again from scratch.

This can sometimes mean the removal of the render, Tyrolean or pebbledash wall coating underneath the exterior wall coating also. Basically in that case, the best way is to start from scratch and do the whole job again.

 

Installing a wall coating on a house

 

In some cases though, the coating and the wall surface underneath can be in such good order that, once satisfied the wall and coating are sound, the resins and solvents from the initial primer coat (sometimes called “slush coat”) that is introduced to the wall prior to spraying the top coating, will soften and bind the existing wall coating to the new coating being added, and the exterior wall coating surface will continue to perform for hopefully the next 25 years.

 

Adding primer to the walls before wall coating

Adding primer to the walls before the wall coating

Removal is often the best way, but not necessary 100% of the time and again, the coating has to be analysed and the house has to be surveyed before a definitive answer can be given on your question, so please accept my apologies for this answer being somewhat generalised but I hope that you can understand why!

I hope this information helps you and I will email you any suggestions that other website users put forward, for your consideration.

Kind regards

Guy Alexander Bell. Bsc.(hons)

Surveyor

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