Dulux Weathershield over Lime Render

[culvermags]

I am involved in a community effort to purchase a Grade 2 listed Pub and save it for the village from the clutches of developers! The pub was re lime rendered some years ago. The last tenant unfortunately repainted the entire property in Dulux Weathershield 18 months ago, I know as I saw the painters at work and begged the tenant to stop! My question is this, should we get this coating removed now, if we don't do we risk damage to the render or do we wait until it starts to blow off? The pub is currently shut and we hope to have a working fund to get work done, so obviously now is the best time to do major works but we will have to be careful how we spend our working capital as the interiors need a lot of work too. The external colour is white although not a brilliant white but I think a different shade would look far more sympathetic. Any ideas of costings also gratefully received.

 

[Nigel Watts]

My advice would be to wait until the exterior needs to be redecorated. It is usually the state of the woodwork which determines this and doing the two together will save the cost of having to scaffold the building twice.

How much it will cost to remove the Dulux will depend on how well adhered it is. If the Dulux has been applied over sound, well carbonised lime render it will be stuck on very firmly indeed and will require chemicals to remove it, followed by a pressure wash to remove the chemicals. If it was applied when the lime render was fresh or over a lime wash it might be rather more friable, and may come off more easily. Either way, don't use any kind of abrasive or mechanical means for removing the paint which will be harder than the underlying lime render. My next door neighbour tried sandblasting the paint off his 1840s stucco and ruined it. Once the paint layer had been penetrated in a few places the blasting took off more stucco than paint.

 

[culvermags]

Thanks for your reply. The lime render was a few years old and had lime paint on it. So hopefully as time goes by the Dulux may start to flake off and therefore come off more easily. So long as we are not risking damage by leaving it it sounds like we can let it be for a while and focus on the inside of the pub, decor wise plus any other hidden horrors we may discover!

 

[andrew gayton]

Film forming modern paint will of course restrict permeabilty, therefore leading to eventual saturation of the underlying fabric. Impermeability increases according to the number of coats which were applied, moreso, obviously, if a sealant were used to prime the render prior to painting. Saturated fabric will be subject to cycles of freeze/thaw which can impact on it severly. I would suggest that carefully heating the paint will be the best way to remove it. The interstitial moisture will heat, then expand, and result in the paint blistering off the surface with minimal mechanical effort. This avoids the need for chemicals and the associated clean-up.

 

[Nigel Watts]

Andrew I am sure you are right, but how urgent a problem is this?

My house was rendered in lime stucco in 1840 and before the end of Victorian period it had had impervious oil based paint applied to it. Layer after layer was built up, followed by more modern paints in the later 20th C, including modern gloss, Sandtex and emulsion paint - in all nearly 1/8 of in inch. Despite all this, only a relatively small proportion of the original stucco failed in the 100 - 150 or so years the lime was clad in impermeable paint.

 

[garnett]

Hello

I had an interesting case 10 years ago when somebody did this to a listed building. Dulux claim that this paint is porous.

In preparation for the enforcement I contacted the technical specialist at English Heritage. Surprisingly they were ambivalent about its use. It is not as good as lime, but not as bad as cement based products. At the time we had some high profile failures of mineral paint systems. It was used successfully as an alternative on Brighton Pier.

In my area we have a lot of hard lime and cement historic stucco. As long as you use the one without the bits in, it does the job.

Lime is a great material. It value apart from aesthetic, is that it gives a building a second chance if something fails such as a leak roof or rain water goods. You need to be more careful checking for failures which could let water into the walls.

Hard hat on ready for the barrage!

Regards

Garnett

 

[andrew gayton]

Andrew I am sure you are right, but how urgent a problem is this?

My house was rendered in lime stucco in 1840 and before the end of Victorian period it had had impervious oil based paint applied to it. Layer after layer was built up, followed by more modern paints in the later 20th C, including modern gloss, Sandtex and emulsion paint - in all nearly 1/8 of in inch. Despite all this, only a relatively small proportion of the original stucco failed in the 100 - 150 or so years the lime was clad in impermeable paint.

Hello Nigel,

The problem is as urgent as each particular scenario dictates; if there are signs of associated failure, then the situation will ideally need to be remedied in an appropriate manner. Failure can be anything from tell-tale internal condensation and associated mold growth to bulging and detachment of render coats due to ingress of water through external cracking. Careful assesment and monitoring will inform what and when needs to be done. Lack of maintenance and ill informed post build intervention will increase the risk of failure/s.

 

[andrew gayton]

Hello

I had an interesting case 10 years ago when somebody did this to a listed building. Dulux claim that this paint is porous.

In preparation for the enforcement I contacted the technical specialist at English Heritage. Surprisingly they were ambivalent about its use. It is not as good as lime, but not as bad as cement based products. At the time we had some high profile failures of mineral paint systems. It was used successfully as an alternative on Brighton Pier.

In my area we have a lot of hard lime and cement historic stucco. As long as you use the one without the bits in, it does the job.

Lime is a great material. It value apart from aesthetic, is that it gives a building a second chance if something fails such as a leak roof or rain water goods. You need to be more careful checking for failures which could let water into the walls.

Hard hat on ready for the barrage!

Regards

Garnett

Hello Garnett - the vast majority of paints are permeable; just that some are more so than others. The planning inspectorate agreed with my view some years ago that a timber framed building (newly repaired in an appropriate manner) would in the long term suffer through the unauthorised use of modern paint.

 

[garnett]

Hi Andrew

I would hope to get a similar response from th inspectorate with a cob building down here. It gets more grey in my early to mid Victorin stucco covered rubble buildings. Indeed I had a case a while back where the AMS objected to the removal of an 1840 unpainted cement stucco as it was on of the ealiest post Roman examples of the material!

Garnett