Flat roof - best sealant recommendation?

RedvGreen

RedvGreen

RedvGreen

Soldato
Joined
2 Dec 2009
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Location
Midlands
Hi all,

Since we are due some good weather allegedly, our flat roof garage and back room need redoing. Have looked at felt, and i believe it simply needs a coat of sealant paint which will fix it up until such a time as we can afford to get it pitched.

What I don't know however, is what brand is suitable and how effective it is?
 
I used Black Jack on the felt roof of our shed last year.
I'd expect most bituminous paints would do though.
Held up fine over the past winter.
Wanted a quick cheap fix as getting a new shed this summer.
 
Looking at various things for our shed at the moment.

Looks like Isoflex is very highly rated. Not cheap, but apparently works really well.
 
I used Isoflex last year to fix a small leak in our flat roof and not had a problem since.

Imo of all the DIY sealers it seems to be the best. If you have a large area to cover it's going to get expensive though.

Also if you do attempt this yourself get a cheap disposable boiler suit, some old shoes, gloves, a throw away paint tray and roller/stiff brush.

No matter how hard you try to be tidy the stuff gets every where and is a nightmare to clean off. Once finished bag every thing up and throw it away.

Also Isoflex has a really thick consistency to other products which can make it hard to apply, I found pouring it straight from the tin forming a small a puddle then spreading it out from there worked best.
 
6m x 5m flat garage roof... Felt wasnt damanged but is VERY tired... Evidence of water ingress around most joints.
We did quite a bit of research, asked a few roofers and finally settled on a product called Cromapol.
Started by clearing roof, used an algae killing spray on the whole roof, let that work its magic, stiff broomed the whole roof to remove any loose debris and then painted a thick layer on all joins and the very edges, jamming it into any gaps etc. Let it go off then did another pass like this.
Then went over the whole roof, gradually working back to where the later was. Left an area approx 1m square and did that the next day.

Worked well, very well and in theory it should last a few years giving us time to save up for a new roof.

As above, leave the tin(s) somewhere very hot for a few days running up to doing the job. Wear old clothes, old shoes, long gloves and a hat.
Brushes go in the bin, as do the clothes... It gets everywhere and doesnt come off easily!
 
I've used Bostik Flexacryl previously and it's absolutely amazing stuff. It will go on in any conditions, over dirt and in water, etc. I'm not sure I'd want to pay to cover an entire roof in it though, might be more for minor repairs.

It has fibreglass mixed into it as well for added resilience. Be prepared to throw away anything it touches (brushes, clothes, etc).
 
Used isoflex over the weekend.
Oooohhhh.... stinky.

Recommendations:
Get the primer, it helps.
Wear crap clothes that you expect to throw away immediately after, or disposable overalls
Goggles or protective eyewear needed.
Gloves. Good grippy ones.
Would recommend a mask for the vapour, it's petroleum based.
Dunk the tin in hot water for a while before hand. Makes it easier to stir and paint on.
Decent stick for stirring. There's gunk at the bottom that needs mixing in.
Think about order of operations. You can't move over an area you have coated.
Wide brush, 5" worked. Was a cheap one from screwfix. Thew away immediately after.
Don't be stingy with the coating. 0.5 to 1mm thick. 4 litre tin will cover about 4-5 square meters.

They recommend a second coat, haven't got around to that yet. If you leave it to long between coats then it's recommended that you put more primer over it.
 
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