Repaint Roof

[robtheplod]

Hi All, I'm getting ready to paint the roof late April (in a poly tunnel) and am just getting everything together and sorting my method of attack. The roof itself is in good condition with just about 5 or 6 small(ish) patches of rust so this is to get on top of it all before it becomes a bigger job. Generally the paint is very faded and scratched (more so than the pics show really), So, this is just to spruce it up and give it a new coating. It has marked out sections where its non-slip and wondered if these could be painted over and keep some of this grip?

 

I've taken on board all info I can find on the forum and have come up with the following.

 

Ignoring all the remove mushrooms/apply edging tape etc my method is:

 

• Sand down rust spots.
• Treat rust spots with Vactan, then use this as the primer in these areas.
• Wash roof (with sugar soap?), scrubbing really hard on the textured areas.
• Sand down roof to give a key
• Wipe roof with white spirit and cloth
• Paint... (usual roller and layoff brush method) - probably 3 coats?

 

Does this all look OK?  Have I missed anything out vital or got anything in the wrong order as I'd ideally not want to do this job again for a while!  any comments or recommendations very much appreciated.

 

Rob

 

 

 

 

[Bee]

Sounds OK to me, As I'm sure you know, preparation is part of the key to success but I think its also important to put sufficient paint on. A coat of paint is very thin, and rolling it on can lead to thin spots. I reckon three coats is probably sensible. Others will likely disagree but that looks like a well painted roof and another 2 or 3 coats will probably mean a total of 6 or 7 layers in all, an enviable covering of paint.

[BEngo]

Try a patch of the non-slip areas first.  This will tell you whether there is still sufficient grip after painting. 

If not you will need to scabble the roof off.

 

Otherwise OK, but patch  prime over the Vactan as well.

N

[Mike Hurley]

I would use panel wipe not white spirit.

[dmr]

From the photos it looks like very localised damage rather than paint failure to me.

Take the rust spots right back to bare steel and use a good primer, no need for Vactan if you get to bare steel.

Several coats of undercoat to build the level flush with the existing paint, and carefully sand to level. If you then want to paint the whole roof then gently sand the whole lot (except any non slip bits) and put one or two coats of paint on.

 

...............Dave

[matty40s]

You cant sand non slip so you need to have some wire brushes in order to get a key on the paint... and get ready to use plenty of elbow grease. 

(You dont need to degrease after using this, just have a beer)

[mark99]

Pray the sun does not shine hard in April in a polytunnel.  Seriously take a temp gauge in, although you may find the paint tells you it's too warm.

[GRLMK38]

32 minutes ago, mark99 said:

Pray the sun does not shine hard in April in a polytunnel.  Seriously take a temp gauge in, although you may find the paint tells you it's too warm.

 

Agreed - it could be very warm during the day and cold at night in April.  Watch out for drips from the polytunnel roof.

[Slim]

8 minutes ago, GRLMK38 said:

 

Agreed - it could be very warm during the day and cold at night in April.  Watch out for drips from the polytunnel roof.

To say nothing of the spider poo.  ?️

[mark99]

35 minutes ago, Slim said:

To say nothing of the spider poo.  ?️

 

One polytunnel I used I had to jury rig a tarp across the roof (one of those cheap B+Q blue plastic ones) to keep the spiders from pooing direct on roof.

 

 

Edited March 6, 2021 by mark99

[robtheplod]

Thanks so much for all the replies. Good to know the process is broadly correct. Never considered spider poo so thats a new one on me!  Hope the weather is dull!!

 

Is there any merit in painting rather than rollering the roof if the paint coat could be thin, especially over the sanded areas?

[Slim]

I'm no painter but I thought the procedure was to apply with a roller then lay off with a really good quality brush. That's what I've always done. Speed with finish. Others may think differently.

[pearley]

On 05/03/2021 at 20:40, matty40s said:

You cant sand non slip so you need to have some wire brushes in order to get a key on the paint... and get ready to use plenty of elbow grease. 

(You dont need to degrease after using this, just have a beer)

Wire cup brush in an angle grinder ok or too harsh?

[Tonka]

Hoover attached to sander stops a lot of the dust.

Panel wipe instead of white spirit

Gently sand between coats