Hello. 1930's render advice please.

DarrenEWard

DarrenEWard

New Member
Hi all, I'm new to the forum. I'm a painter with a distant background in ancient monument conservation - flint and lime work mostly.

I've started repairing the render to my 1930's house which was pretty shot in a few places. Cutting out the blown areas has grown to be a larger than I'd planned for. I found the cavity wool insulation (white wool) was damp which is most likely why the render is in such a poor state - It's now been removed. Right now I'm hovering between taking all the render off and starting again or continuing with the repairs. The front is in the worst condition, the sides and back are pretty fair with a few cracks to repair.
can any one advise please - first, the most suitable mix for the scratch coat and finish coat. The original scratch coat seems to be made from a red sand and the top coat seems to be a sharp silver or white sand. Am I right to expect this to be a sand, lime and cement mix and if so would that be the case for both coats? The brick under the render is different to the face brick on the lower half of the house and appear to be the same brick as was used on the interior walls of the house.
IMG_2835.JPG

IMG_2839.JPG

Second - although I feel competent to make the repairs (if properly informed) I cant help wondering if this is worth repairing or would you advise replacing?

The house is in Brighton.

Cheers
Darren









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DarrenEWard said:
Hi all, I'm new to the forum. I'm a painter with a distant background in ancient monument conservation - flint and lime work mostly.

I've started repairing the render to my 1930's house which was pretty shot in a few places. Cutting out the blown areas has grown to be a larger than I'd planned for. I found the cavity wool insulation (white wool) was damp which is most likely why the render is in such a poor state - It's now been removed. Right now I'm hovering between taking all the render off and starting again or continuing with the repairs. The front is in the worst condition, the sides and back are pretty fair with a few cracks to repair.
can any one advise please - first, the most suitable mix for the scratch coat and finish coat. The original scratch coat seems to be made from a red sand and the top coat seems to be a sharp silver or white sand. Am I right to expect this to be a sand, lime and cement mix and if so would that be the case for both coats? The brick under the render is different to the face brick on the lower half of the house and appear to be the same brick as was used on the interior walls of the house.
View attachment 51531
View attachment 51527

Second - although I feel competent to make the repairs (if properly informed) I cant help wondering if this is worth repairing or would you advise replacing?

The house is in Brighton.

Cheers
Darren









0
Click to expand...
Let me ask you a question, if you had holes in your socks would you repair them or replace them?
 
Agree start again fresh even consider a Roughcast with Weber pral over a keycoat , that way you won’t have to paint it and will have bags of character to the house
Maybe even leave some sections of brick exposed the bricks look good too
 
johniosaif said:
Hack it all off , do you want to go lime render or sand /cement
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Hi johniosaif, I'd want to to go with what was originally used which I'm assuming was lime based (?). I figure the render was designed to move with the building - the brickwork mortar seems to be lime based. I reckon those old guys new what they were doing : ) Do you have any thoughts on it?
 
Vincey said:
Agree start again fresh even consider a Roughcast with Weber pral over a keycoat , that way you won’t have to paint it and will have bags of character to the house
Maybe even leave some sections of brick exposed the bricks look good too
Click to expand...
Thanks Vincey. Sounds like a plan - though I think I would go with a scrapped finish - seems more in keeping with the original.
 
DarrenEWard said:
Hi johniosaif, I'd want to to go with what was originally used which I'm assuming was lime based (?). I figure the render was designed to move with the building - the brickwork mortar seems to be lime based. I reckon those old guys new what they were doing : ) Do you have any thoughts on it?
Click to expand...
If you want to use what was used in the first place you will have to have it analysed but even then that sand quarry will probably be under a Housing estate now and the dust that may have been used will be different as for using lime and sand if you are doing that originality you will have to paint it with a lime wash or something similar using sandtex etc will defeat the object as the lime won’t be able to breath.
Just hack it off and render with double washed sand, good clean sharp sand and cement with water proof for the first coat and just double washed and cement for the top coat with its waterproof or a plasticiser which ever you prefer or just throw a bit of lime putty in to make it more workable
 
i thought that if you stripped off over half of the render on a property, building control says that an External wall insulation system must be fitted.
 
malc said:
i thought that if you stripped off over half of the render on a property, building control says that an External wall insulation system must be fitted.
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You have to be joking can’t they keep their noses out of anything? Would that work for him the overhang of his roof tiles is not enough for that sort of thickness
 
malc said:
all overhangs are covered as part of the EWI systems.
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Bloody hell this opens up a whole can of worms I’ve just been on their site and it says window reveals have to be done as well, what about being able to open the window some ar tight enough with just render let alone insulation
 
Mouldyoldspudgun said:
If you want to use what was used in the first place you will have to have it analysed but even then that sand quarry will probably be under a Housing estate now and the dust that may have been used will be different as for using lime and sand if you are doing that originality you will have to paint it with a lime wash or something similar using sandtex etc will defeat the object as the lime won’t be able to breath.
Just hack it off and render with double washed sand, good clean sharp sand and cement with water proof for the first coat and just double washed and cement for the top coat with its waterproof or a plasticiser which ever you prefer or just throw a bit of lime putty in to make it more workable
Click to expand...
Cheers Mouldyoldspudgun. That makes sense - I figured I wouldn't be able to "replicate" the mix but would rather find something I could mix that would be on par with what was originally used based on what is available today. Do you think it would be a fair assumption that it's lime based? I've read that the preferred mix would be something along the lines of 1:1:6 - cement, hydrated lime and sand. I've seen a number of houses around here that have been re-rendered using cement and they dont seem to hold up too well - some quite substantial cracking. To be honest I thought I could repair the render but now it seems best to take it off and get a pro in to re-coat. Also, I'm up for lime wash or silicate paint.
Cheers again for your input
 
malc said:
i thought that if you stripped off over half of the render on a property, building control says that an External wall insulation system must be fitted.
Click to expand...
Hi @malc - thanks for the info. I'm starting to think it best to stop where I am and repair. Looking into TWI it would change the character of the house way too much given the application thickness and as @Mouldyoldspudgun mentioned - I don't think the windows would open!
 
DarrenEWard said:
Cheers Mouldyoldspudgun. That makes sense - I figured I wouldn't be able to "replicate" the mix but would rather find something I could mix that would be on par with what was originally used based on what is available today. Do you think it would be a fair assumption that it's lime based? I've read that the preferred mix would be something along the lines of 1:1:6 - cement, hydrated lime and sand. I've seen a number of houses around here that have been re-rendered using cement and they dont seem to hold up too well - some quite substantial cracking. To be honest I thought I could repair the render but now it seems best to take it off and get a pro in to re-coat. Also, I'm up for lime wash or silicate paint.
Cheers again for your input
Click to expand...
The 1:1:6 would give you 1:3 to be fair, I personally would think it’s sand and cement because it’s a thirties house but without having it analysed you wouldn’t know, the colour is usually because of the sand but don’t take that as gospel. Your surrounding houses that have been rendered may not have been done right or it may just be weak points ie above and below door and window openings because of the weight being diverted to the sides of the openings
 
Mouldyoldspudgun said:
The 1:1:6 would give you 1:3 to be fair, I personally would think it’s sand and cement because it’s a thirties house but without having it analysed you wouldn’t know, the colour is usually because of the sand but don’t take that as gospel. Your surrounding houses that have been rendered may not have been done right or it may just be weak points ie above and below door and window openings because of the weight being diverted to the sides of the openings
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Thanks @Mouldyoldspudgun - all good information and much appreciated.
 
Mouldyoldspudgun said:
Bloody hell this opens up a whole can of worms I’ve just been on their site and it says window reveals have to be done as well, what about being able to open the window some ar tight enough with just render let alone insulation
Click to expand...

on EWI systems the area of brickwork that shows behind the insulation boards are given a coat of thermorend to all window heads and reveals . so that it makes no difference to the windows opening.
 
DarrenEWard said:
Hi @malc - thanks for the info. I'm starting to think it best to stop where I am and repair. Looking into TWI it would change the character of the house way too much given the application thickness and as @Mouldyoldspudgun mentioned - I don't think the windows would open!
Click to expand...

EWI systems are a different application and needs a qualified operative to fit the system. of course all windows and doors will open .
building control are trying to bring our housing stock up to a decent standard.
 
malc said:
EWI systems are a different application and needs a qualified operative to fit the system. of course all windows and doors will open .
building control are trying to bring our housing stock up to a decent standard.
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I have to disagree with that I’m not sure they are bringing our housing stock to a decent standard more like doing the bidding of the latest eco fad
 
Mouldyoldspudgun said:
I have to disagree with that I’m not sure they are bringing our housing stock to a decent standard more like doing the bidding of the latest eco fad
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every tower block in this country has to be brought up to a high insulation standard. 30s built council houses get the same treatment .
 
malc said:
we have been fitting EWI for over 30 years so i don't think is the 'latest fad'
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We used to see the Poles fitting it on the office blocks in the nineties but just because you fit external insulation doesn’t mean it makes your home of a superior standard it just gives You cheaper heating bills but one day the fad will stop just like With Artex and Tyrolean and I suspect all the Polymer based crap people are putting on the outside of their homes
 
Mouldyoldspudgun said:
If you want to use what was used in the first place you will have to have it analysed but even then that sand quarry will probably be under a Housing estate now and the dust that may have been used will be different as for using lime and sand if you are doing that originality you will have to paint it with a lime wash or something similar using sandtex etc will defeat the object as the lime won’t be able to breath.
Just hack it off and render with double washed sand, good clean sharp sand and cement with water proof for the first coat and just double washed and cement for the top coat with its waterproof or a plasticiser which ever you prefer or just throw a bit of lime putty in to make it more workable
Click to expand...
Hi Mouldyoldspudgun. Thanks for the advice. May I ask the ratio of double washed sand (which I assume is rendering sand?) to sharp sand for the first coat please? I notice that the render on the house seems to be a finer sand (red) for the first coat and a much courser white sand as finish coat - do you think I should follw suit for repairs or is it not important?
 
DarrenEWard said:
Hi Mouldyoldspudgun. Thanks for the advice. May I ask the ratio of double washed sand (which I assume is rendering sand?) to sharp sand for the first coat please? I notice that the render on the house seems to be a finer sand (red) for the first coat and a much courser white sand as finish coat - do you think I should follw suit for repairs or is it not important?
Click to expand...
We use half and half sand wise for the first coat, as long as you get the same sort of finish it won’t matter on the colour assuming you get the mix right
 
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