Coating concrete roof tiles

Author
Discussion

Pistom

Original Poster:

5,904 posts

174 months

Monday 2nd June
quotequote all
My house has concrete roof tiles and they're starting to go powdery and retain moisture for longer. This is also speeding up the growth of moss and algea.

The house is being scaffolded for other work so I'm thinking of taking the opportunity to clean the roof and am wondering if coating it will extend their life and reduce moss and algae growth.

I'm wondering whether to use a silane/siloxane coating which penetrates into the tile or maybe an acrylic roof paint but I wonder if a roof paint is just going to bring maintenance issues in the future if it peels?

Perhaps just leave the roof as it is. It's water tight and replace the tiles when the roof needs it?

sherman

14,435 posts

230 months

Monday 2nd June
quotequote all
Do nothing to roof tiles.

You will pay double in the long run.
Once to pointlessly clean and seal your roof and then again to reroof it anyway.

fourstardan

5,569 posts

159 months

Monday 2nd June
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Surely getting moss off with a brush isn't a bad idea?

Cow Corner

548 posts

45 months

Monday 2nd June
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I would think very carefully before cleaning roof tiles (unless their is a very specific need), particularly when it sounds like they are reaching the end of their life anyway. Cleaning them is likely to just speed up their demise (both from the act of cleaning itself and because you will be exposing the defective surface) and adding a coating to a defective tile sounds like a fools errand. So as long as it's watertight, I would leave well alone.

Just one thing to note, some types of concrete tiles can contain asbestos.

Tin Hat

1,415 posts

224 months

Monday 2nd June
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Don’t waste any time trying to refresh these tiles, they are pretty much the cheapest covering for a pitched roof and they are generally very forgiving - I would simply replace them when they finally run out of steam.

fourstardan

5,569 posts

159 months

Monday 2nd June
quotequote all
I can't imagine how much of a pain in the arse it would be painting roof tiles.

Mr Magooagain

11,694 posts

185 months

Monday 2nd June
quotequote all
Just spray tiles with an anti moss/algae. Use a proven good product, don’t brush and just leave until you can change tiles.

OutInTheShed

11,428 posts

41 months

Monday 2nd June
quotequote all
People pay a fortune for a 'sedum' roof, that's just pretentious moss innit?

I used some acryllic concrete sealer for some thing else, I'm sure the destructions said something about 'don't use this on roof tiles, use our roof tile sealer.'

So there are products out there for the job.

Pistom

Original Poster:

5,904 posts

174 months

Monday 2nd June
quotequote all
Several suggestions to do nothing and that's tempting as there's nothing wrong with them yet other than a bit of pointing needed on ridges and valleys but my thinking is that silane would bond the surface whilst remaining breathable.

My thinking also is that tiles which are increasingly porous will deteriorate faster from freeze thaw whereas silane might reduce that.

smifffymoto

5,064 posts

220 months

Tuesday 3rd June
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Mr Magooagain said:
Just spray tiles with an anti moss/algae. Use a proven good product, don t brush and just leave until you can change tiles.
Moss has now been classified as a plant so theoretically needs to be removed mechanically,pressure washed or scraped. Then apply a biocide like Bac 50.
Be careful with biocides!

Pistom

Original Poster:

5,904 posts

174 months

Tuesday 3rd June
quotequote all
smifffymoto said:
Moss has now been classified as a plant so theoretically needs to be removed mechanically,pressure washed or scraped. Then apply a biocide like Bac 50.
Be careful with biocides!
I'm not sure why moss needs to be removed in all cases but in my case and in this style of house, it does look unsightly.

The thing is, pressure washing could be very disruptive on a surface which is already turning dusty from aging but until tiles are starting to physically break up, I think replacing tiles which are just aging is unnecessary.

However my thinking is that a penetrative coating which rebinds the surface and is hydrophobic could extend the life.



OutInTheShed

11,428 posts

41 months

Tuesday 3rd June
quotequote all
The moss looks unsightly when the seagulls rip it off the roof and throw it on the drive or at my car.

Personally I think a shiny new Barratt House roof looks wore than one mellowed by a bit of lichen and moss.

Pressure washing seems like a good way of damaging the tiles, and unless you can do it from above, driving water and crud under the tiles.

If the tiles eventually seriously crumble, I'd replace them with solar panels.

Tiles do get more frost these days, as people improve loft insulation!.

Pistom

Original Poster:

5,904 posts

174 months

Tuesday 3rd June
quotequote all
OutInTheShed said:
The moss looks unsightly when the seagulls rip it off the roof and throw it on the drive or at my car.

Personally I think a shiny new Barratt House roof looks wore than one mellowed by a bit of lichen and moss.

Pressure washing seems like a good way of damaging the tiles, and unless you can do it from above, driving water and crud under the tiles.

If the tiles eventually seriously crumble, I'd replace them with solar panels.

Tiles do get more frost these days, as people improve loft insulation!.
You're doing a good job of talking me out of doing this. The main reason I was thinking of it in the first place is because I'm having £2.5K of scaffolding in place so trying to get the most out of it but I think there could be more damage done than good.

megaphone

11,219 posts

266 months

Tuesday 3rd June
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I've jet washed a few roofs, it's a messy job, make sure you don't block your down pipes. You'll need to start at the top down and try not to force too much water up under the tiles. Will look good for a few years until the tiles go black again and the moss returns.

Cow Corner

548 posts

45 months

Tuesday 3rd June
quotequote all
Some pictures would be useful, to understand their current condition and why you are considering works.

But from what you have said, I would strongly recommend against jet washing or using any other type of mechanical or aggressive cleaning method on roof tiles which it sounds like is already getting close to the end of their lifespan.


Lotobear

7,978 posts

143 months

Tuesday 3rd June
quotequote all
Cow Corner said:
Some pictures would be useful, to understand their current condition and why you are considering works.

But from what you have said, I would strongly recommend against jet washing or using any other type of mechanical or aggressive cleaning method on roof tiles which it sounds like is already getting close to the end of their lifespan.
100% - concrete roof tiles are, in the main, surface colour coated/sealed and pretty much rely on this to remain impervious. Pressure washing will remove the surface coating, expose the matrix and lead to accelerated wear/porosity.

....picture of concrete roof tiles (wrongly) aggresively pressure washed by some cheery happy go lucky tikes and now open surfaced and porous


Pistom

Original Poster:

5,904 posts

174 months

Tuesday 3rd June
quotequote all
Cow Corner said:
Some pictures would be useful, to understand their current condition and why you are considering works.

But from what you have said, I would strongly recommend against jet washing or using any other type of mechanical or aggressive cleaning method on roof tiles which it sounds like is already getting close to the end of their lifespan.
Thanks. Looking at them, I'd say they're halfway through their life, so another 10-20 years before they deteriorate to the extent that they need changing and I'm in agreement that jet washing will reduce that significantly as I'd just be removing material for more material to degrade but if the moss was removed, a herbicide applied and then a siloxane coating applied to re-bind the surface, that might extend their life


TA14

13,094 posts

273 months

Tuesday 3rd June
quotequote all
This looked to be a reasonable approach: "BAC50 = benzalkonium chloride

Take note of PPE and wind direction, plus if you're using anything other than the stuff for domestic use and even then watch dilution rates.

Best is mechanical clearing of the big lumps then spray and leave. After that rain washes off the rest."

From this thread: https://www.pistonheads.com/gassing/topic.asp?h=0&...

rossub

5,166 posts

205 months

Tuesday 3rd June
quotequote all
smifffymoto said:
Moss has now been classified as a plant so theoretically needs to be removed mechanically,pressure washed or scraped. Then apply a biocide like Bac 50.
Be careful with biocides!
Be careful in what way? I spray my roof every couple of years myself as it's a Bunglaow.

reggie747

201 posts

142 months

Tuesday 3rd June
quotequote all
Use Sodium Hypochlorite in a watering can (albeit a few cans) let it soak for 15 mins then jet wash off (not on full pressure setting) to remove all traces of sh!te.