I forgot to add, there was no external supervision. No Architect or Structural engineer overseeing the work, no NHBC involvement just me, the brickies and a labourer.
Help required - Big concerns with mortar mix
- Thread starter selfbuild1
- Start date
Sponsored Links
Too much plasticiser leads to excessive air entrainment (ie tiny voids like an aero bar) and BRE note 362 (Building Mortars) states
"Whilst air content is not highly critical, it should be between 10 and 18%. This can be checked on site with a simple air-pressure device (see BS4551). Too much air-entrainment leads to poor durability and low compressive and bond strength ..... The manufacturer will give a guide to the amount of plasticiser related to the cement content of the mortar, but the optimum will depend on a number of factors, in particular the type and grading of the sand"
Generally excessive entrainment will show as a soft mortar, possibly powdery, with the ironed face wearing off. It will become progressively worse over time as the joints weather, - with accelerated degradation over time.
Mortar will beome more susceptable to rain penetration as the pores soak up more rain rather than shed it down the face, and yes this can lead to effloresence.
There may be some cracking, and loose bricks. Blockwork may crack also, but it may be for different reasons, so it needs to be investigated
Proper repointing will give a weathering face to protect the whole wall. Patch repointing should probably be avoided.
Whether areas need rebuilding, or if compressive strength is an issue will depend on the site specifics. Any particular areas of specific load bearing eg point load from beams etc or bearings should be looked at.
"Whilst air content is not highly critical, it should be between 10 and 18%. This can be checked on site with a simple air-pressure device (see BS4551). Too much air-entrainment leads to poor durability and low compressive and bond strength ..... The manufacturer will give a guide to the amount of plasticiser related to the cement content of the mortar, but the optimum will depend on a number of factors, in particular the type and grading of the sand"
Generally excessive entrainment will show as a soft mortar, possibly powdery, with the ironed face wearing off. It will become progressively worse over time as the joints weather, - with accelerated degradation over time.
Mortar will beome more susceptable to rain penetration as the pores soak up more rain rather than shed it down the face, and yes this can lead to effloresence.
There may be some cracking, and loose bricks. Blockwork may crack also, but it may be for different reasons, so it needs to be investigated
Proper repointing will give a weathering face to protect the whole wall. Patch repointing should probably be avoided.
Whether areas need rebuilding, or if compressive strength is an issue will depend on the site specifics. Any particular areas of specific load bearing eg point load from beams etc or bearings should be looked at.
Woody, this is fantastic info, thank you very much.
The symtoms are exactly as you suggest. Soft Mortar, powdery in places where it has been more exposed to damp weather. It is progressively getting worse. I have some cracking mostly along the mortar lines and mostly around areas of high stress ie Lintel Ends and at the top of walls and gables.
Woody, I am not sure if are you a structural engineer? If you are and are interested in some work I am about 1 hour south of Birmingham, just off the M1. I would be very interested if you could take a look and give an informal (no report required) opinion on what you think would be the best move forward. Ideally before End of Day Monday but that is not crutial.
If you are interested drop me an email at '[email protected]' asap. This would, of course, be fully chargable work.
The symtoms are exactly as you suggest. Soft Mortar, powdery in places where it has been more exposed to damp weather. It is progressively getting worse. I have some cracking mostly along the mortar lines and mostly around areas of high stress ie Lintel Ends and at the top of walls and gables.
Woody, I am not sure if are you a structural engineer? If you are and are interested in some work I am about 1 hour south of Birmingham, just off the M1. I would be very interested if you could take a look and give an informal (no report required) opinion on what you think would be the best move forward. Ideally before End of Day Monday but that is not crutial.
If you are interested drop me an email at '[email protected]' asap. This would, of course, be fully chargable work.
Just out of pure curiosity,
How much plasterciser should you use with a mix of say 1:1:6 ???
are we talking about a mugfull, morre or less ???
How much plasterciser should you use with a mix of say 1:1:6 ???
are we talking about a mugfull, morre or less ???
Sponsored Links
Cementone Cemplas Plastisicer is 60ml - 125ml per 25Kg OPC Cement, Febmix is 70ml - 140ml per 25Kg OPC Cement.
Matercrete includes a pastisicer and recommends half the stated amount be used.
Although it depends on the cannister I would estimate about 3 capfuls per mix. (This is very vague though). Ideally I would measue out the number of capfuls you need per mix and then then from there on you should be able to repeat that for the rest of the build.
Matercrete includes a pastisicer and recommends half the stated amount be used.
Although it depends on the cannister I would estimate about 3 capfuls per mix. (This is very vague though). Ideally I would measue out the number of capfuls you need per mix and then then from there on you should be able to repeat that for the rest of the build.
He wishes....
Fortunately I am not a SE. (and I give thanks for this daily ).
I wont be able to nip down south sorry.
In this instance it may be better to engage a local SE, as it may develop further and the structural aspects will be the issue, and you need expert opinion on this.
Just have a chat with the brickies and see what they say. Make your concerns clear regarding the structural aspects and the longevity of the mortar and that it may prematurely degrade over a short time.
Most of all, try not to fall out about it at this stage.
Suggest that a SE is engaged as an independent expert, and ideally that they should pay his fees or you offer to pay half on the basis that if the walls are significantly sub-standard, then your half of the fees are reimbursed - along with the costs of the remedial work. Pick someone who is independent and not known to the brickies or yourself.
The instruction should be to comment on the current condition and the longer term lifespan of the mortar and walls. You also want to know what remedial work is required to ensure a 'normal' life of the mortar, and what the work will cost. If extensive work is required, then the SE should prepare a remedial schedule and be engaged to manage the work - all at no cost to you.
The brickies will have insurance if they are a bona-fide company, and if so its no big issue to them, if you claim via their insurers.
From you meeting with them, you will get a feel for how the matter will progress. But unless the brickies offer to rebuild it all, then you will need professional opinion on the current and future condition of the walls before you can move it forward.
But remember that the concern is not for now, but 2/5/10 or more years in to the future - especially if you may sell the property in this time
).I wont be able to nip down south sorry.
In this instance it may be better to engage a local SE, as it may develop further and the structural aspects will be the issue, and you need expert opinion on this.
Just have a chat with the brickies and see what they say. Make your concerns clear regarding the structural aspects and the longevity of the mortar and that it may prematurely degrade over a short time.
Most of all, try not to fall out about it at this stage.
Suggest that a SE is engaged as an independent expert, and ideally that they should pay his fees or you offer to pay half on the basis that if the walls are significantly sub-standard, then your half of the fees are reimbursed - along with the costs of the remedial work. Pick someone who is independent and not known to the brickies or yourself.
The instruction should be to comment on the current condition and the longer term lifespan of the mortar and walls. You also want to know what remedial work is required to ensure a 'normal' life of the mortar, and what the work will cost. If extensive work is required, then the SE should prepare a remedial schedule and be engaged to manage the work - all at no cost to you.
The brickies will have insurance if they are a bona-fide company, and if so its no big issue to them, if you claim via their insurers.
From you meeting with them, you will get a feel for how the matter will progress. But unless the brickies offer to rebuild it all, then you will need professional opinion on the current and future condition of the walls before you can move it forward.
But remember that the concern is not for now, but 2/5/10 or more years in to the future - especially if you may sell the property in this time
Woody,
Your advice is again fantastically accurate, concise and appropriate. You are indeed a master, a guru of all surveyors. I am truly amazed how you can do this without seeing the property, I can only assume you have some psychic powers or access to a secret US spy satellite.
After contacting the Brickies again this morning to confirm when they will arrive we have arranged 5:00pm tomorrow. Not today as expected, but at least they are coming.
I suspect the Brickies do not have any imdemnity insurance but I will get this confirmed tomorrow. I also suspect they will not offer to rebuild and will only offer minor remedial work. Some careful negotiations coming up I think.
My search for an SE still continues. I have contacted more than 12 so far and all are either too busy, do not feel they have enough experience of this type of problem or just don't want to get involved. If anyone has any recommendations for SE's in the Milton Keynes area I would be very interested to hear. Shytalkz, I am not sure if you are interested, I suspect you may be a little to far away though, if not, please email me.
Your advice is again fantastically accurate, concise and appropriate. You are indeed a master, a guru of all surveyors. I am truly amazed how you can do this without seeing the property, I can only assume you have some psychic powers or access to a secret US spy satellite.
After contacting the Brickies again this morning to confirm when they will arrive we have arranged 5:00pm tomorrow. Not today as expected, but at least they are coming.
I suspect the Brickies do not have any imdemnity insurance but I will get this confirmed tomorrow. I also suspect they will not offer to rebuild and will only offer minor remedial work. Some careful negotiations coming up I think.
My search for an SE still continues. I have contacted more than 12 so far and all are either too busy, do not feel they have enough experience of this type of problem or just don't want to get involved. If anyone has any recommendations for SE's in the Milton Keynes area I would be very interested to hear. Shytalkz, I am not sure if you are interested, I suspect you may be a little to far away though, if not, please email me.
Would love to do it, but a) nothing that way (and nothing on at Knebworth!) atm that I could share travelling time/costs with and b) way too bizzy as it is. Try www.findanegineer.co.uk, if you're struggling: at least one member of staff has to be a qualified SE to be allowed on there, as it's run by IStructE. Found four within 20km of MK postcode: AB Design, Scott-White, Neil Johnson and Tapsell Wade, don't click on specialism, leave as-is. Same four come up under more precise headings, so that appears to be your lot.
If you get really stuck then email me via profile.
As does the IStructEFortunately I am not a SE. (and I give thanks for this daily
. Seriously bud, very sound advice that you've given out there - I have a feeling that, had you taken the correct career path, you could have been fashioned into a reaso SE. But you went the wrong way and ended up as SE-lite, heyho!!!Thanks Shytalkz,
I have not tried two of those yet, I'll give them a call.
I have not tried two of those yet, I'll give them a call.
this self build chap is a cool dude aint he?
i would want to be ripping open someones chest by now.
i would lay money on the labourer being a bit keen with his dollop but i would also reckon that the brickies will try and get out of it if their pride/competence is questioned.
pointing wont work!
ultimately it does not matter if the muck was wrong or not, you paid for a brickwork shell not a pile of stored up trouble. whatever the excuse or reason;the work is wrong.
good luck with it.
btw
i think your approach is the right one, dont give them the chance to get offended and walk away.
i would want to be ripping open someones chest by now.
i would lay money on the labourer being a bit keen with his dollop but i would also reckon that the brickies will try and get out of it if their pride/competence is questioned.
pointing wont work!
ultimately it does not matter if the muck was wrong or not, you paid for a brickwork shell not a pile of stored up trouble. whatever the excuse or reason;the work is wrong.
good luck with it.
btw
i think your approach is the right one, dont give them the chance to get offended and walk away.
Just for an update I can confirm the brickies did turn up yesterday, on time just as they promised. Although they were a little defensive at the beginning I feel my non aggressive, no blame approach made a difference and they soon relaxed off and we had some very good, honest, discussions. In total they were on site for two hours.
Because the symtoms are showing up in a number of areas it would not be practical to go through them all here (suffice to say Woody seems to have identified most of them even without seeing the property). And, as is the nature of these types of problems it is also very hard, even for experienced professionals, to come up with a definite reason for each of them. The bottom line though is that they are taking the problems very seriously and have agreed that where the problems are down to them they will correct them.
The difficulty is that even they are not sure what the cause of the issues are (and they were the two senior partners and their head bricky with over 60 experience between them). We have therefore agreed to get an SE in for an independent analysis at their cost to document each of the issues, determine the causes and list out the remedial work.
With regard to the platiciser the labourer has assured the partners that he did not use excessive amounts. I am not sure the partners belive him but as they said 'without standing over him it is difficult to say he is incorrect'. I do know that for all 78 litres were used but can see the quality of the sand was poor so more than the expected 6 Litres would have been used. (78 still looks to be excessive though).
The next step is to get an SE on site. They have suggested a few names so guess what I will be doing today.
I will update further when we hear more but for now I would like to thank everyone that has replyed. The knowledge that has been provided has made a real difference to me and is helping me both get through the problems and get the build done right. Thank you.
Because the symtoms are showing up in a number of areas it would not be practical to go through them all here (suffice to say Woody seems to have identified most of them even without seeing the property). And, as is the nature of these types of problems it is also very hard, even for experienced professionals, to come up with a definite reason for each of them. The bottom line though is that they are taking the problems very seriously and have agreed that where the problems are down to them they will correct them.
The difficulty is that even they are not sure what the cause of the issues are (and they were the two senior partners and their head bricky with over 60 experience between them). We have therefore agreed to get an SE in for an independent analysis at their cost to document each of the issues, determine the causes and list out the remedial work.
With regard to the platiciser the labourer has assured the partners that he did not use excessive amounts. I am not sure the partners belive him but as they said 'without standing over him it is difficult to say he is incorrect'. I do know that for all 78 litres were used but can see the quality of the sand was poor so more than the expected 6 Litres would have been used. (78 still looks to be excessive though).
The next step is to get an SE on site. They have suggested a few names so guess what I will be doing today.
I will update further when we hear more but for now I would like to thank everyone that has replyed. The knowledge that has been provided has made a real difference to me and is helping me both get through the problems and get the build done right. Thank you.
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
