Exterior Paint problem

Well Jon you could be right, yet for the time being I will keep an open mind. I have to the best of my ability studied those pics and I am not convinced that it is a rendered surface.

Dec

 

Hi guys, well its an interesting problem eh ?

I am as much in the dark as you are. I need to organise scaffolding to get up there and see what's beneath the paint. Its a 1930's semi so it may be a formica finish as has been suggested or it could be a plywood that's been painted. Until I get up there and get a closer look I can't tell you. The photos posted are all we have at the moment.

Its going to be a while before I can get up there but when I do I'll have a carefully scrape the loose paint off and see if I can find out what's underneath and post some more photos.

I can tell you that the adjoining semi has done away with the black/white original look and rendered the whole lot so maybe they had a problem too. Can't confirm why its rendered as it was done before the occupants moved in. But a neighbour told me he was the last to paint my house and he had a real problem making it look OK.

I'll ask him this week if he can remember what the finish of the board was .. that might be quicker.

many thanks
Bill

 

1930's It's sure to be render. look in loft and you should see rough sawn planks 6"x1" cladding. Outside they put a membrane (building paper/ felt ) then plaster lath then render, maybe lime mortar ((?)) Unless this was replaced with ply/ etc recently

Carefull not to lean ladder onto the white bits/render. I've learnt that to my cost in the past and cracked render thinking it was render onto blocks.
Ask your neighbour if he put stabilising solution on I come across this flaking masonry often where people (decorators inc) will apply stabiliser to any surface , dusty or sound

 

I have been inside the attic and had a look


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working from inside out: there is a plastic membrane right across the apex, behind that is roofing felt and behind that is a flat smooth white board about 1/4" - 3/8" thick that feels very hard. My best guess is that it's a flat asbestos sheet.

And if I look up from outside where that yellow patch is in the photo and ignore all the flakey paint .. its definitely flat, no rendering that I can see unless he was a damn good plasterer.

It may not be original, the asbestos sheet could be a replacement sometime in the past. I had a word with the neighbour who painted it 20+ years ago and he recalls it being "some sort of sheet but I can't remember what .. and all I did was rub it down and put undercoat and gloss on it"

So if it is asbestos .. that may explain why why paint hasn't stuck to it .. along with being South facing ?

Hope that helps

 

Wots up with you lot? The white paint has been painted over a powdery yellow coat. It's powdery paint on render. Scrape it off and stabilise it - then re-paint it. Simples.

(Call yourself tradesmen?)

 

Well lads.
I stand by everything I previously said, and, not only was the paint coming off, nothing to do with stabiliser, but if stabiliser, had've been used correctly in the first place, this problem wouldn't be here.

 

Oh it it's asbestos then ?

As billin says If is asbestos, the neighbours undercoat and gloss is the cause. Years ago it had to be an alkali resisting primer, but a thinned coat of masonry followed by 1 thicker coat of masonry is the standard.

I would scrape off (no stabiliser on the asbestos) and apply the thinned masonry paint etc.

 

So after scraping off the peeling white, I'm left with the yellow, which if sound I can leave and rub down ?

But no stabiliser is needed before the thinned masonry paint ?

Doesn't the powdery surface of the board / yellow need to be sealed before applying the masonry paint or is the thinned masonry coat doing that job instead ?

thanks

 

billm
This is from Dulux -

Stabilising primer is a solvent - based primer specially formulated to seal unstable areas which remain powdery and chalky after the surface has been thoroughly prepared for painting with masonry paint. It should not be used as a general purpose sealer on normal or sound surfaces (e.g. not powdery and chalky after the surface has been thoroughly prepared). New or sound bare surfaces should only be sealed with a thinned first coat of the masonry paint itself.

The yellow/cream on your boards, needs to be sealed as this appears to be causing the problem as it's probably very chalky/powdery, so just using a thinned masonry over this will land you back with this same problem. It will suck the life out of paint unless it's sealed and the correct sealer for this problem is a stabiliser.

It could be done using a "pliolite" masonry which is solvent based and thinning that first , to seal and bind it together but really your best option is stabiliser. I wouldn't go down the pliolite route first in your case.

The decision..............
is yours.

 

Thanks Growler.

As I have to hire scaffolding to get up there I only want to do the job once. So I'll hit it with stabilising solution, then the masonry paint.

Do I still need to apply a coat of diluted masonry paint after the stabiliser or put it on straight from the tin ?

How long after the stabiliser can I start applying the masonry paint .. being Solvent based does it have to dry overnight ?

thanks

 

Not sure which type of asbestos you have but there's some advice here, before you go diving in with a scraper or sandpaper.

http://www.hse.gov.uk/pubns/guidance/a16.pdf

 

Saw a bloke the other day painting his house with a small portable hydraulic crane.

Might be easier than scaffolding?

 

My thoughts remain same..stabilising solution is not alkali resisting.
We all know that solvent undercoat/gloss on asbestos brings us to this problem. The surface originally was probably smooth. Then the alkaline in asbestos attacks the solvent u/c etc etc~~~.

If it was render or some other material and powdery, yes indeed use stabiliser. etc

When I get this problem on soffits/ soil pipes etc
If the board is asbestos I would dampen with a garden sprayer/hose, scrape,wipe off as much as possible with damp rags allow to dry and either apply an alkali resisting primer followed by masonry paint.or a thinned coat of masonry etc
several jobs where i have done this and gone back 6/7 yrs later to re-dec and soffits sound.

Good luck

I'm not trying to score points here just joining in the discussion.
Try asking Dulux if stabiliser will work on alkali surfaces. (if it is asestos)

 

The scaffolding is sorted, a guy up the road has a tower he's happy to lend me. Time scale wise I'm looking to make a start within the next 2 - 3 weeks.

So today I decided to call Dulux in Slough for their advice :

After scraping away the loose paint, if the surface underneath is not powdery apply a coat of 10% diluted masonry paint first and then give it a further full coat 2 - 3 hours later.

However if the underlying surface is powdery then apply Stabilising Solution first then a coat of undiluted masonry paint. If the stabilising solution dries to a shine then I should give that a light rub down to provide a key.

Thanks for all the comments guys, it seems you are all correct. I appreciate your help.

Cheers
Bill

 

Well done billm

This is very technical....

Whenever I look at a masonry job, I always lick a good bit of spit onto my finger, then dab it onto the wall and watch how quickly the paint sucks it dry. This will tell you how chalky or powdery it is.

For the easily frightened among us.. do not put your finger back into your mouth and wear some protective glasses when scraping. (Can't be too careful).

It's wise to also have a quick look at the instructions on the tins/ tubs just to check all is in order.