Dot Dab Plaster wall - 35mm box? Plasterer at odds with electrician

[JLeague]

As part of my spec I said that I wanted 35mm back boxes. The walls have been taken back to the brick and will be dot and dabbed with plasterboard and then skim finished.

Electrician said that he can just screw the backbox onto the wall without digging into the brick because onces its dotted and dabbed the wall will come forward 35mm and cover the box.

Plasterer is adamant that is wrong and has said that he will do dot and dab but the wall will not come out as much so the boxes will protude.

 

[Baddegg]

Dot and dab is a quick way to refurb old buildings whose render coat has lost adhesion...used a lot down here on old terrace buildings...never gonna be 35 mm though, cost alone would prevent it, done properly it would finish as per the original inch ish 25 mm render and plaster finish,personally I’d put 35 mm boxes in but sometimes as per the op there’s a tight window.....but don’t forget depending on age of building, you may not even get the 25 mm you need in some areas!

 

[Mike Johnson]

Dot and dab or any type of finish should not be used on top of blown render, it should all be hacked off and then you can hard plaster.

 

[Baddegg]

Dot and dab or any type of finish should not be used on top of blown render, it should all be hacked off and then you can hard plaster.

I assumed that was a given ?

 

[Ian1981]

You don't dot and dap on ceilings, I thought that would be understood and did not need explaining, perhaps you are too young to remember the traditional way of constructing domestic buildings.

Ha I miss read your post , you said plasterboard only.

 

[pirate]

If a kitchen fitter can't trim down a unit to fit the space he's not a "fitter" at all. They are adept at putting in "filler" boards to make up a gap of a few inches, and clearly prefer to do that rather than trim a larger unit to fit.

 

[Mike Johnson]

Well everyone else miss reads the post's so why not you as well, we seem to need the minutiae in all explanations or someone will come back with a question that should be a given.

 

[telectrix]

You don't dot and dap on ceilings, I thought that would be understood and did not need explaining, perhaps you are too young to remember the traditional way of constructing domestic buildings.

you mean lath and plaster with half a horse's hair in the plaster, or straw walls?

 

[Zerax]

You don't dot and dap on ceilings, I thought that would be understood and did not need explaining, perhaps you are too young to remember the traditional way of constructing domestic buildings.

I'm too young too Mike... like this you mean ?

 

[UNG]

Call me old fashioned, but IMO plasterboard should only be used on ceilings, dot and dab was invented to speed up construction no other reason, any muppet can do it, very little skill involved, with hard plaster, cupboards and fittings can be fitted directly to the wall no need for noggins, but it does need skill which seems to be lacking in the building trade these days.

Dot and dab was introduced in an attempt to increase the insulation value of walls.
For a decent plasterer dot and dab is no quicker than bond and skim

If a kitchen fitter can't trim down a unit to fit the space he's not a "fitter" at all. They are adept at putting in "filler" boards to make up a gap of a few inches, and clearly prefer to do that rather than trim a larger unit to fit.

Trimming a cupboard is the easy bit it's trimming the doors that generally causes the problems
Although I do know a couple of companies that will build kitchen cupboards and doors to customer sizes which does solve a lot of space problems

 

[nicebutdim]

Trimming a cupboard is the easy bit it's trimming the doors that generally causes the problems
Although I do know a couple of companies that will build kitchen cupboards and doors to customer sizes which does solve a lot of space problems

In most instances it would be more expensive to resize doors (if at all possible), than to dump them and fit new. Regardless, someone would have to pay for any modifcations and it would be a rather extreme solution to the problem of the spark not wanting to chase 35mm boxes.

 

[Mike Johnson]

Dot and dab was introduced in an attempt to increase the insulation value of walls.
For a decent plasterer dot and dab is no quicker than bond and skim

Absolute not, dot and dab was only introduced to speed up construction for mass produced domestic building no waiting for drying periods when a three layer plaster construction was normal to plaster a house, there is no thermal advantage to plasterboard unless it has a insulation layer in its construction, in which case a 35mm box would fit behind it, dot and dab is completed in one day, traditional plastered walls takes three days, plus a drying period, don't know if you have ever worked on any sites, but you obviously have not seen traditional plastering done correctly.
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you mean lath and plaster with half a horse's hair in the plaster, or straw walls?

Not straw wall, but cob walls.

 

[nicebutdim]

Occasionally I've seen old houses where walls have been battened and boarded, but that was a cheap fix over rough walls. When such old houses are refurbished, those walls are picked bare and floated out in plaster.

The whole idea of dot and dab is alien to me and I really struggle to understand why someone would want to finish a solid wall in this way. Is there a significant saving per sq meter on finished walls and does dot and dab impact on sale value of houses?

 

[Mike Johnson]

Most punters now days do not know the difference between dot and dab and traditional wall plastering, its only used in this modern age in very high end domestic building, the last one I was involved with at 67million had to import the plasterers from Poland to get the finish they required, the saving is in the time it takes to do a good job, as I said dot and dab in a day traditional takes many days.

 

[nicebutdim]

They could have contracted plasterers from NI as this is how they finish walls every day of the week.

 

[Mike Johnson]

One of the walls in the mansion was over 20M long and looking from one end there was not a fault or flaw to be seen, craftsmanship at its highest, mind you the electrics left a lot to be desired, but these high end domestic buildings only have a life expectancy of 10:20 years.

Sample of their work: HARRISON VARMA - Recherche Google - https://www.google.com/search?rlz=1C5CHFA_enGB718GB718&sxsrf=ALeKk02OePxRYbN7kVapUq7v5qfq4uYb5Q:1598043022929&source=univ&tbm=isch&q=HARRISON+VARMA&sa=X&ved=2ahUKEwjQsN6Vlq3rAhWCiVwKHaWqAuQQjJkEegQICRAB&biw=1268&bih=619

 

[OnlQQker]

Dot & Dab can get you out of a whole host of problems with houses built in the 50/s 60's, especially when existing walls are unlevel, cracked and contain different finishes like multi finish, fillers and cement, as well as umpteen coats of different paints. All of which cause bubbling, cracking and different drying times when plastering over, unless of course you strip it back to bare walls which takes forever cuz most of the base coats are strong mortars!
Saying that Browning is just as bad to strip back as well.

On solid brick walls though then best to lime plaster it so it can breathe!

 

[Baddegg]

Most punters now days do not know the difference between dot and dab and traditional wall plastering, its only used in this modern age in very high end domestic building, the last one I was involved with at 67million had to import the plasterers from Poland to get the finish they required, the saving is in the time it takes to do a good job, as I said dot and dab in a day traditional takes many days.

where was this then mike?....I could phone 5 British plasterers now who could do it, don’t believe the hype it’s about the cost of the tradesmen not a skills shortage....

 

[Mike Johnson]

Look two post above, and I can assure you it's about the skill not the cost.

 

[Baddegg]

Look two post above, and I can assure you it's about the skill not the cost.

Looked at it? Not seeing anything a British spread couldn’t do...

 

[Mike Johnson]

On solid brick walls though then best to lime plaster it so it can breathe!

Hah you have been reading too many blogs on Facebook re French building, walls do not breathe they allow water vapour to pass, in the UK we have more water vapour outside our buildings than inside, but we don't get many solid brick walls since the victorian times, in 1954 when the building regulations first came out cavity wall construction became the normally accepted construction method and the introduction of two coats of Browning and finish became the norm and if you ever saw how much interstitial condensation happens on the inside of a cavity wall you would not question its permeability.
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Looked at it? Not seeing anything a British spread couldn’t do...

If they are that good then I doubt they are available.

 

[Baddegg]

Everyone’s available for the right price and any works on that scale would’ve been planned months and or years in advance so they would’ve been available, not denying they are obviously very good spreads, it’s a lovely finish, I just don’t agree with your statement that the building contractor HAD to go abroad for the skill set and I stand by my statement it’s all about money, I’ve mates who’ve worked with Russian tilers in places like Nando’s who are no better than local boys but the difference is they are cheaper work 20 hrs a day and don’t dare complain about working conditions or health and safety....

 

[OnlQQker]

="Mike Johnson, post: 1652630, member: 43554"]
Hah you have been reading too many blogs on Facebook re French building, walls do not breathe they allow water vapour to pass, in the UK we have more water vapour outside our buildings than inside, but we don't get many solid brick walls since the victorian times, in 1954 when the building regulations first came out cavity wall construction became the normally accepted construction method and the introduction of two coats of Browning and finish became the norm and if you ever saw how much interstitial condensation happens on the inside of a cavity wall you would not question its permeability.
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I have been in many a listed building which has been patched up with sand/cement on the inside and caused no end of havoc.

 

[Mike Johnson]

We will have to agree to disagree, when you work exclusively in that sector the mind set is totally different, on the first project for HV we had six different sets of sub-contractors until we found the ones that suited our work ethos, those guys are now almost exclusively on HV projects, and incidentally the H&S is of the highest standard as it is in the Joinery shop which makes all the internal fittings, in fact during one of the builds they caused a shortage of Walnut veneer as they bought all they could get hold of to enable book matching the 4.5M high doors, all forty of them.
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I have been in many a listed building which has been patched up with sand/cement on the inside and caused no end of havoc.

If they where listed buildings where was the Preservation Officer, Architect, Structural Engineer, or even the Quantity Surveyor when this was going on.

 

[Deuce]

Thanks

So it seems plasterer was correct - 10-15mm for adhesive, 12mm plasterboard, 3mm skim so about 25-30mm.

I have just spoken to the electrician and he said he had quoted and assumed the new plasterbaord would cover 35mm - if I still want 35mm boxes then its extra or he can fit 25mm boxes which he said really is what everyone asks for.

I am on a tight schedule and for 30 sockets he is looking at 2/3 days more work - I might just have to bite the bullet and go with 25mm boxes.

We're doing the same right now and wanted 35mm boxes, but as per your sums above, even a 25mm back box once dot/dabbed, the board and then skimmed becomes a 30mm deep box - which actually was more then sufficient for the switches and sockets we're using - so it became a none issue.

Are you sure 30mm depth isn't enough anyway? The only ones we had to use a 35mm deep box for was a FCU and an underfloor heating thermostat. The rest (LAP flush, screw-less switches and sockets) all fitted provided there was a little over 25mm depth, which there always will be with dot-dab and 12.5mm board + skim.

In the end we actually went for using foam adhesive in place of the dot and dab, and we used 15mm packers to ensure the plasterboard was spaced sufficiently proud from the block wall as we mounted each board = reliable 30mm depth across all back boxes and no unnecessary chasing.

 

[cliffed]

The PD boxes were the best….

 

[telectrix]

dot& dab is the work of Satan. dhould be banned outright. lazy man's way of finishng off a wall theat should be plastered properly. our house was done in 1956 and most is still as good as when originally done. then again. all internal walls are made of brick. not some ubder seasoned kiln dried fire material coverede over with carrdboard.

 

[Mike Johnson]

Modern housing use Dot and Dab for speed of construction it's all about cost, and let's face it very little skill required to slap a bit of plasterboard on a wall, all internal partition walls should be of brick/block construction so you can't hear someone burp in the next room, but again one less trade and speed of construction comes first.

 

[Deuce]

Most punters now days do not know the difference between dot and dab and traditional wall plastering, its only used in this modern age in very high end domestic building, the last one I was involved with at 67million had to import the plasterers from Poland to get the finish they required, the saving is in the time it takes to do a good job, as I said dot and dab in a day traditional takes many days.

I live in a 9 year old house on a typical modern housing estate. It's one of the larger houses but still just a 4 bed detached with detached double garage. It's just brick construction, not stone, nothing fancy. About 4 years ago we bought it for £365k. I think it originally sold for £230k but the town has picked up value quite a bit since then.

It has solid walls throughout, no stud walls at all and is fully wet plastered, no dot/dab anywhere - other than the extension I just added.

No idea why, it surprises everyone - myself included when I realised how quiet it is room to room and how easy it is to put up a shelf. But for whatever reason, some contemporary house builders for 'normal folk' still go this route.

I wonder if it might perhaps be that increasing claims for cracked skim finishes as the house bakes out for the first year has proven more costly to deal with than solid walls and solid plaster in the first place? I could see some house builders making that judgement. It's also probably not that expensive when you're putting up 200 houses to have a team of very skilled foreign plasterers (back then at least, pre brexit) enjoy a few years of gainful employment at a decent rate by their standards back at home.

I totally agree that Polish plasterers are fantastic. I too have worked in some incredibly expensive houses and I've seen them at work. A house next to Margaret Thatcher's old digs had a team in there that managed to finish a 4 storey stairwell and adjoining landings in fully polished plaster, seamlessly top to bottom, in less than a week. It looked like marble when they had finished - and it was, genuinely, flawless. Even the reflections across it were not distorted looking along the wall, it made me question whatever skill I previously thought my own two hands had to offer the world!!

 

[Mike Johnson]

Cracked skim finish's happen due to bad workmanship, either in the sub strata, plaster mix or insufficient time between coats, you never see cracks in polished plaster when applied correctly, most low to mid house builders are all about cost and maximising profit, and who can blame them for that, but it should not be too the detriment of the construction.

 

[Deuce]

Cracked skim finish's happen due to bad workmanship, either in the sub strata, plaster mix or insufficient time between coats, you never see cracks in polished plaster when applied correctly, most low to mid house builders are all about cost and maximising profit, and who can blame them for that, but it should not be too the detriment of the construction.

I was just making the point that a skim of plaster is more liable to crack over time, for whatever underlaying reason, compared to solid plaster.

Both can crack of course, but in my experience the 3mm skim is more liable to show hairline cracks than 15mm solid plaster.

 

[Mike Johnson]

It can of course, but not if its skimmed when the undercoat is still sufficiently damp that it takes in some of the plaster in the skim and forms an homogenous bond that dries out at the same rate as the undercoat, one of the biggest mistakes is plastering on a dried out wall so a bond does not happen.

 

[swaRRR]

Cracked skim finish's happen due to bad workmanship, either in the sub strata, plaster mix or insufficient time between coats, you never see cracks in polished plaster when applied correctly, most low to mid house builders are all about cost and maximising profit, and who can blame them for that, but it should not be too the detriment of the construction.

New build houses move when they settle and always experience cracking.

 

[Mike Johnson]

You may well believe this is the case, but new build houses move because they are inadequately constructed, as I have said earlier, I have been involved with some very high end housing and any cracking of the internal plaster would not be tolerated, unseasoned timber used in timber frames and internal walls, probably deck cargo brought over from, who knows where, during the drying process of this timber probably causes excessive movement and hence cracking, something the RICS, ARIBA, ICE and ISE have been putting forward as the reason for cracking in Court cases for quite a number of years. My flint stone house is over five hundred years old is built straight off a chalk strata bed and has no foundations and has not moved or cracked anywhere.

 

[westward10]

You may well believe this is the case, but new build houses move because they are inadequately constructed, timber framed and internal walls, all unseasoned timber and probably deck cargo brought over from, who knows where, the drying process of this timber causes excessive movement and hence cracking, something the RICS, ARIBA, ICE and ISE have been putting forward as the reason for cracking in Court cases for quite a number of years. My flint stone house is over five hundred years old is built straight off a chalk strata bed and has no foundations and has not moved or cracked anywhere.

How do you know it hasn't moved in its 500 year history. It could have suffered several movements of which you have no record of.

 

[Mike Johnson]

I think I would have seen this by the out of line or plum walls, even when the front to the house was blown off during the second would war the rest of the house including the 9M floor beams survived, external corners are still plumb and are of the very small hand made bricks of the original vintage.

And a certain 90 year old farmer and family that have been in the area since year dot, that have intimate knowledge of when the houses where built for and by the farm hands, it was built as two cottages and converted into one in 1957.

 

[westward10]

I think I would have seen this by the out of line or plum walls, even when the front to the house was blown off during the second would war the rest of the house including the 9M floor beams survived, external corners are still plumb and are of the very small hand made bricks of the original vintage.

The place could have subsided and partially collapsed within 12 months of its first build and you have no clue as to this so to have an opinion on its integrity is optimistic to say the the least it could have been rebuilt several times in its 500 year old history.

 

[Mike Johnson]

Nope see additions to above post.

 

[westward10]

Nope see additions to above post.

They have an intimate knowledge and record of its 500 year old history.

 

[Mike Johnson]

Yes they have farmed this area for longer than that and where the original owners of the property we only say its 500 years old because that is the first time it changed hands, their records go back further than that.

 

[Mike Johnson]

This discussion has gone on long enough, the original post is about Dot and Dab plaster to paraphrase someones previous post.