Advice on plastering

[jpadie]

Hello all

 

There's some bald patches in a bathroom of a late 16th century cottage that needs some tlc.  Not sure how original the brickwork is!

 

Any advice on plastering this?  Would a lime render be best?

 

Pics at this link as they were too big for the site: https://photos.app.goo.gl/H3aiCWh5wWqrwohG7

 

tia

Justin

[twice round the block]

Looks like someone previously used a sand / cement mix on one area.

 

Has the damp problems been totally resolved, that blew the plaster in the first place?

A lime mix will let it breath.

I would put some uni bond on first and let it dry, before applying render.

[jpadie]

i doubt the damp problem will ever go in a house this old (and listed).  but it's no worse now than over the last decade.  

 

it's quite possible that someone did a job with a mortar - there was a polish builder here for a while who was a decent chap but had never worked with lime.  oddly i saw something similar on grand designs, brickie had never worked with lime so did everything as a concrete/mortar.  

 

thanks for the advice!  I've got some mapei primer that might work as a bonding agent and make the job a bit quicker.  i will have a read of the package once I find my specs.

[Redbeard]

Is that newspaper I see round the waste branch? Probably try pushing in quite a sticky lime mortar as a base. Don't know what the Mapei primer is and whether it would be compatible with the 'breathability' of lime.

[jpadie]

On 04/05/2024 at 15:27, Redbeard said:

Is that newspaper I see round the waste branch? Probably try pushing in quite a sticky lime mortar as a base. Don't know what the Mapei primer is and whether it would be compatible with the 'breathability' of lime.

Yup.  It's newspaper.   I'm looking forward to seeing the date when I take it out. 

 

Its not a waste pipe in fact.  It's a flue from an oil burner.  Gets a little toasty which is why I'm hesitant to use spray foam to fill the gap before rendering.  

[Redbeard]

Oh! Is that not plastic soil pipe? It looks very like it, and there appears to be a 40mm-ish spigot at the back, against the wall. Maybe all is not as it appears. So the 'plastic soil pipe' is metal flue pipe and the 'spigot' isn't a spigot??

 

I certainly would not use foam. Pack it with dense Rockwool as used for EWI fire-breaks and around flues.

[jpadie]

Part of the flue is connected to an old bread oven that's now bricked up.  The spigot you see is the feed from the oil boiler.  The flue then goes into a chimney stack. 

 

Going back to the advice on lime mix, before I start this work was the intent that it was just a lime and sand mix or adding lime to a sand and cement mix?  I think one needs a hydrated lime?

[Redbeard]

If I had any lime putty I would do quite a putty-rich lime putty/gritsand mix, say 2-2.5 to 1, to make it nice and sticky. Lime putty is hydrated lime, but it's not the (dry) hydrated 'bag-lime which is mainly used as an admixture to sand/cement to improve plasticity.

[jpadie]

Thanks.  I think I can make lime putty.  Or buy it from nearby. 

 

Wil post back with results when I get around to this job....