Weathershield keeps blistering and coming off every year ?

[joesoap13]

Hi guys, would appreciate advice please.
as you can see, my exterior wall keeps blistering and have to scrape it off every year.
always used deluxe weathersield.
usually late on when weather goes colder.
wall is circa 16 years old.
rest of house ok, just this new part ?
any advice welcome, thinking of trying sandtex ?
is it just bad render ?
cheers.

 

[robinbanks]

Are the aluminium tape sections over the coping stone joints indicative of earlier attempts to stop large amounts of water leaking into the wall?

 

[conny]

You need to scrape it off at the start of the year, (meaning, from spring). Leave it bare for a few weeks and hope you get good weather, i.e. no rain. There is damp/moisture in the wall/render and it needs to dry out thoroughly before painting again. Give it a good brush down with a stiff brush occasionally to remove any flaking bits and then paint towards the end of summer, maybe mid-August, before the damp weather starts moving in again. Let it dry completely between coats.

If the render is hollow when you tap it lightly with a hammer/mallet, it may indicate that it is blown and their is moisture rapped between the wall and the render. Only solution for that is to knock it off and re-render after allowing the brickwork to dry out.

 

[joesoap13]

Hi Robin.
yes, put aluminium tape on joints, to see if it helps.
that was last year, so didn’t help !
yesterday, put felt strips on edges to form a drip strip , siliconed them and screwed on,as coping only sticks out 20 mil, ish !
wondered if water was going behind render.

 

[joesoap13]

Thanks conny, done all of that over the years, except leaving it bare, during summer, for a long spell, did it last year after we had the long heat wave.
it only takes one shower and it’s wet again,so do it when nice and dry , weather unpredictable hear.
wall is sound .
as you can see, it is a party wall, next doors conservatory buts up to it, hence the height,he dot/ dabbed plasterboard on his side of the wall inside, says no probs.
seems taking it all off again got be only solution, drastic though !!
when I scraped it only a few weeks ago, the blisters were very large, only 2 mins and it was off.
if I leave it, they go down , so did it when it was wet.
water was in the blisters, hence drip strip this week.
thought weathershield was waterproof, and breathable, and best !?
cannot understand how wall is wet behind paint to blister ?
not unless they didn’t doc it properly ?
thanks for both replies, much appreciated.

 

[robinbanks]

What are your thoughts on through-coloured render (k-rend, weberpral etc) ?

 

[joesoap13]

The whole house is normal render with no problems, so assume it is just bad render.
the two small walls of my conservatory, which was built and rendered when wall was done, the top coat of render came off as I pulled the weathershield off. the top coat render was soaked under the paint ?
scratch coat was ok ?
I re- rendered the top coat myself and it has stopped ok since.
couple of years..
I have never rendered before, but had a go, couple of square feet !

 

[DiyNutJob]

You can see the wall is wet. You have to stop the water. You can use hybrid polymer sealant on openings.

 

[joesoap13]

Hi D . Thanks for reply.
what openings ?
cannot find anywhere water ingress to cause it!
the wet you can see is water running paint on top of wall,down off coping, hence putting new drip strip on.plus Ali tape on top joints.
as this photo shows you.
will try anything , it’s a pain.

do you mean seal the whole wall before re painting it, after I remove more of the old stuff?
cheers

 

[DiyNutJob]

Large amount of water can get in from hairline cracks, no matter how small. Using sticky tape of any kind won't work. Water will just seep through it. The dampness in the wall looks deep down and inside the wall. It's either coming from above or behind.

Until you stop the water, any new paint will just fail again. Any cracks in the mortar between the coping stones will let water in. Water hanging on the bottom edge of the coping stones will move towards the wall. If there is crack between the stones and wall, that will let water in. A bead of sealant between stone and wall can work. Also a bead in the stone joints can work.

 

[lostinthelight]

What is wall constructed of and what's on the opposite side

 

[oakysmokyjoky]

Hi guys, would appreciate advice please.
as you can see, my exterior wall keeps blistering and have to scrape it off every year.
always used deluxe weathersield.
usually late on when weather goes colder.
wall is circa 16 years old.
rest of house ok, just this new part ?
any advice welcome, thinking of trying sandtex ?
is it just bad render ?
cheers.

When you say scrape it off, what do you mean - down to the render or just the top paint layer? Also what's the orientation of the wall, ours faces north west and gets zero sun during the year...may have to set up some IR heating!