Morter for concrete tile roof

mrgts4, Jan 10, 11:36pm
I am going to be painting my concrete tile roof. I need to do a bit of maintenence first, replacing a few tiles and remortering the ridge cappings. What morter should I be using and what is the best paint to use, do I need a undercoat or can I just use the no primer required paint? They are monier tiles, approx 17 years old. Cheers

newtec1, Jan 11, 12:30am
They used to use sand and cement,but they now use a similar product, i can't remember the name [flexi. ] which is more pliable and won't crack as easy, if at all. If you use just sand and cement mix a little motarflex with it and it will be much easier to use. The same product they use for blocklaying. You don't need much,just a small container for the whole job. As for painting they don't normaly use house paint, it is a special tile paint and will need to be sprayed.

newtec1, Jan 11, 1:08am
Flexipoint may be the name. ?

golfdiver, Jan 11, 1:44am
If you are doing a full mortar repair, you need to rebed it with sand and cement mortar then point it with Flexi point or point master. If the roof has any colour on it at all you will need to use a high solids binder coat. This is essential as if it is not used the paint will fall off. Much like trying to paint over chalk. First up you need a moss kill then a waterblast to get the roof spotlessly clean. I'm not sure what paint you should use as even Resenes are trying to steer clear of concrete tile coatings. Gerard have a great high solids sealer but it is only available as a supply and coat job. As said airless spray painting provides the best results. No doubt somebody will say to just paint it but I've been in this industry for 23 years and I've seen a lot of jobs fail because of short cuts being taken. Again make sure you seal it!

mrgts4, Jan 11, 1:59am
Cheers golfdiver, I hate concrete tiles but even being a roofer the cost of materials to replace with iron is out of my reach. It is a 280sq/m house with a 20deg roof so a big job. I cant believe how poor the paint on these monier tiles lasts, its looked ratty for about 5 years, there is hardly and colour left on them. We did a job at wattyl last christmas and the rep reccommended to just use their roof paint as it was self priming, I wasn't really convinced. Will check out all the paint suppliers

Just going to repair the morter, most of it is fine, just some sections are starting to fall out

newtec1, Jan 11, 2:00am
Exactly. I was involved with roof restorations for a while but my memory fails me at times.Yes replace broken tiles first then waterblast the old lose crap of before you apply the base seal coat, then two top coats with another clear sealer.Guaranteed for for 20 years. A high build paint especially designed for tiles and sprayed as you said.

golfdiver, Jan 11, 2:22am
The coating on Concrete tiles is just an oxide slurry. It looks great for the first few years until the Gloss Efflorescent Protection or GEP coat wears off, then it just looks like crap. The GEP coat is there to stop the white lime salts from leaching out through the top of the tile. Instead in goes out through the bottom. I hate concrete tile roofs too. Give me Long run or a Corona Shake any day.

happychappy50, Jan 11, 2:48am
Flexi point is the product,used it years ago in Oz,try sand/cement with a dash of pva glue,it is self sealing,never failed me yet & it makes the sand/cement mixture slippery,also paint a bit on each piece before applying the"mud",any good quality concrete paint would work,have used PPG exterior acrylic paints with great results,all in the prep though,a decent clean with water blaster after using a mould/ moss cleaner should do the trick,apply with a sprayer . Good luck

mrgts4, Jan 11, 9:44pm
I had a bit of a drive around today and called into Wattyl, who said to use solagard. As it is self priming you just use 3 coats. Resene reccommended using sureseal first then 2 coats of their roof paint, only issue id sure seal is solvent based, how hard is it to clean the airless sprayer with solvent? I also called into paint tec in Wellington who sell APCO paints, never heard of them, are they any good it is made in NZ. They reccommend 1 coat of roof sealer(water based) then 2 coats of their roof paint. Dulux also said to use a roof sealer and roof paint.
What is the best paint, do I pay extra for Resene or is the $115/10l APCO paint alright to use? Cheers

newtec1, Jan 12, 12:44am
I don't know about those paints,but we used to W/Blast first,then a sealer followed by two coats,and just to be sure another sealer to finish.The paints we used were manufactured in Aus,but i can't remember the name.

golfdiver, Jan 12, 4:01am
Those Aussie paints were used by a mate of mine also in the trade. They ended up failing big time and the Aussies didn't stand behind them. He is a decent tradie too. I was talking to the rep at Resenes the other day and he said they were trying to steer clear of concrete tile paint. See if you can get hold of your local Decraguard Agent and by some high solids sealer from him. Danny Mather might help you out, he is a good bugger. That sealer is really good. Then just a high build topcoat or two

ceebee2, Jan 14, 7:43pm
Golfdiver
Maybe we should start a dedicated thread for roof prep / coatings etc. I too want to prep my concrete tiles and respray as to have it done commercially is unaffordable at the mo. I can use a spray gun no prob but the prep must be done correctly as you have "pointed" out.
Question, The grout on my roof has shrunk by an average of 5mm so do I chip it off and start again or moss kill and fill with flexi point or similar.
Excellent thread here.

golfdiver, Jan 14, 8:14pm
I'm not sure how mortar can shrink per se? But if it has cracks in it you can use selleys mortar gap filler in a tube to fill it. I used to rub it in with a finger. Then a 5mm layer of Flexi-point over the top. The roof needs to be really well cleaned, and then sealed. To be perfectly honest, if you are intending to stay in the house long term then I wouldn't bother. Just get it re roofed with a lightweight material

mrgts4, Jan 14, 10:16pm
I am now tending towards saving the 2k plus it is going to cost me for the paint and putting it towards the cost of materials for a reroof. I am worried about the paint later on down the track peeling off and looking like a real mess. At the moment it doesn't look too bad apart from being the wrong colour now compared to the fascia and spouting. Thanks for the advice though.

next-to-normal, Jan 14, 10:22pm
Resene has a nice finish after 3 coats, hi glo good paint

ebygum1, Jan 14, 10:32pm
Appco paints are made by Asian Paint Co. one of the largest paint manufacturers in the world,based in India. I sold this brand for about seven years with no complaints or problems,I have used it myself on our industrial buldings and on a couple of houses. I think your descision to save the money and reroof is a sound one

golfdiver, Jan 14, 10:41pm
That's what I would be doing too. No need for a consent as the roof is over 15 years old and if you can do it yourself then I think that is the way. Coatings look good for a few years but when the gloss level drops they aren't so good. Also you need to be extra vigilant with miss and mould

ceebee2, Jan 14, 10:46pm
Hi
Here is a similar pic of what my roof looks like. not the sides but the top ridge mortar.
http://trademe.tmcdn.co.nz/photoserver/full/357726232.jpg
Do I replace it or clean up and spread the mortar over it?
Cheers in advance.

golfdiver, Jan 14, 10:52pm
Looks pretty badly cracked. Depends on your ability and or your budget. If I was asked to do this it would be a total rebed and point. Which will cost plenty as scaffold will be needed too. If you do it yourself do what I suggested earlier but don't hope for a permanent fix. Cheers

ceebee2, Jan 15, 1:40pm
Many thanks goldiver.

tanyash, Jan 15, 1:47pm
golfdiver do you still do this work or could you recommend someone to replace a few terracotta roof tiles and repair an area of flashing on a roof join ? Thanks

jimgammy, Jan 15, 1:48pm
Hi,

Method to fix that damage is either;

Remove all ridge caps and rebed the entire roof with mortar. Flexi point the ridges once dry.

or

Use a diamond grinding blade to grind back the mortar exposing the edge of the ridge capping. Then flexi point. A contractor will charge $40/m to do this.

golfdiver, Jan 15, 11:31pm
I assume you are in Auckland? I don't really know a lot of guys in the trade up there, but Barrier roof coatings or Edwards and Hardy could take care of it for you

ceebee2, Jun 8, 9:15am
Thanks jimgammy